Been fighting my gas gauge not working in my 84 C10 6.2 diesel. After watching this video, I added a ground directly from the fuel gauge ground to a screw on the cab metal and that fixed everything! So glad I came across your video! Thank you!
That was truly an expert explanation. Thank you for taking the time to make this video, I am building a ‘64 C10 with my daughter and her fuel gauge stopped working, I am confident that we can fix it now, thanks again!
Dave did an excellent job in this video. Gauges and Sending units seem to be mysterious in some fashion but simple in reality. A gauge is best described as that experiment in high school science class winding insulated wire around a nail. When connected to a battery, it becomes an electro magnet. Now, imagine a gauge as a nail on one side wired clockwise, it pushes a paper clip away. A second nail is wound counter clockwise and attracts the paper clip. Now if both nails shared a common ground, a variable resistors, changing the strength to ground makes one side push or become weaker. Same here, except it is inside a gauge. So basically reverse polarity if you can imaging, the common point to ground is a wire wound resistor to ground. In this case, 90 to 0 ohms resistance. If at 45 ohms, both nails have the same push/pull, so the gauge reads? 1/2 full! You got this. As Dave did, placing the lead to a good ground will push the needle completely one direction. (Imagine one nail is strong and the other is dead) The different is at the sender. Dave made another good point, that's using dielectric grease on connections. Under the truck? You bet! On the cluster connector, sure! It keeps them clean and not green as copper traces oxidize. They slip in and out better as well, saving that printed circuit on your gauge cluster. Thanks Dave! Good info for those in town and around, the world! Keep em going folks! DK, ASE master since 1978.
Thanks for watching! You're really going to like the 1965 C10 "Transformation" series of vids we're about to start shooting. Keep an eye out for them later in 2022 or subscribe and you'll get notified when new stuff drops!
Nice video. When testing my sender wire at the guage, the tester light was dim. It had continuity but must of been compromised along the way. Replaced the wire and now is all good. Thanks!
Very good, you explained everything good, I have a 66 C10, I have replaced Guage, new sending unit, still not working, I will recheck all grounds again, thanks this helps me alot, I watch all your videos.
You guys are fantastic I buy everything for my 53 chevy truck from you. This video was an incredible help in me figuring out my gas gauge problems. I recently converted my truck from 6 volt to 12 volt and I am installing a gauge reducer to my gauges. Do I need one, not only for my gas gauge, but also for my battery gauge. Thank you for all your informative videos
Dave thanks for the video, just changed to EFI on my big block 69 c10 restto- mod. Been fighting with my gas gage for a week. You made it so simple. Fixed after watching your video in about 20 min.
@@philup6274 it was not properly grounded. I used rubber washers installing the fuel tank, what happens you over think something. Removed the rubber washers. Working perfectly now. Thanks again
For whatever reason my gas gauge stays high until I hit the brake. When I hit the brake the gauge balances out to the amount I actually have. I’m gonna take a look at it tomorrow after watching this though. Great video man!
Hi David, I took some ohm reading's on my sending unit on my 53 Chevy pickup, I'm reading on empty 18 ohms and full I'm reading 52 ohms. I'm thinking that's not good. When on an early Chevy you said, it should be 30 ohms when full. My guage reads a little less then half when tank is full of gas. When I remove wire off the sender and ground it to itself the guage goes lower. It don't ping to full. Not sure if I have a bed sender unit, and a bad guage. Can you please answer that, it would be great to get this gas guage to work again. Thank you
I have a 1988 gmc sierra 1500 4x4 just bought it the previous owners replaced the fuel pump and sending unit , the guages on cluster does not read looks either empty or nothing any help where to start looks like the ground has been moved
Fantastic video brothers. You got me in the neighborhood. For whatever reason my 85 S-10 goes through gas pumps every so often. I'm on the 3rd or 4th one. Early on mos prolly ethanol. Haven't run that in years and the last one is holding good. But after the last round the gauge is just wonky. Might show half full and then flop over to full, depending on the slosh. Did we put the sending unit in backwards? It's all over the darn place but never shows what it should. Ground? Backwards? The bed is coming off soon so I can get to a short rubber line that is currently spewing gas when the pump is on. Failed at the clamp. (The thing is beyond antique. Ha!) While I'm there thought I might as well see to the gauge. Suggestion? I thank you!! Norm
I have a 12V Gauge. It reads past full when the sending unit isn't even connected. Can you please make a video on how to wire it? This truck was given to me so I do not have the directions.
This is almost always caused by a lack of a 12v source of power to the gauge. The gauge will just drift higher and higher, even well beyond full. Make sure your gauge is getting a 12v power source.
I have a 76 Chevy Nova. The gauge reads full all the time. As soon as power is applied the gauge moves to full. Can I test the resistor behind the gauge before pulling the sending unit?
That typically indicates that you have no 12v power at the gauge. The dash should have a 12v source that supplies the gauge with power. Check that first.
I got a Chevy 350 in my class c RV and the fuel gauge went out last year...seems like I would have to drop the tank to get to the ground wire in the sending unit?
check out our more recent video about fuel gauge troubleshooting. Maybe you'll see something in it you didn't see here. Gauge failure is always a possibility too, however its easy to check and eliminate that as the issue normally.
Hey Dave i have an issue with my 1986 chevy silverado on my gas gage a full tank and the gage reads 3/8 on both sides i replaced sending unit on one side both sides grounded good
Sounds like you have either a bad fuel gauge or a bad 12v power supply to the gauge itself. Did you happen to hook up the new sending unit and test it while it was out? It would be interesting to hear what happened if you did.
I have a '71 chevy. There is no ground on the fuel sending unit, is it supposed to have one? Currently the fuel gauge just shows the needle in about the 3 o'clock position. Is it not having a ground going to be an issue? I've seen in other videos where it doesn't have one.
My power wire is reading 8.4 volts. Only when it leaves the firewall from the fuse box. On the grey wire that comes from the relay reads 12.2. Any idea of what makes it short out? I have went along the wiring and see no visual grounding. It's a 1990 K5 blazer. Running a wire to bypass pigtail directly to fuel pump wire for now.
@@BROTHERSTruckPartsTV thank you for the response I will look into the fuse box! That's where I'm losing the power at. I have 12v on the grey wire at the fuse. 8.4 on the red wire coming back out of EcmB fuse
What side of the terminals does the power go to on the gauge for the cluster is it the terminal on the full side of the gauge and the ground on the empty side
so my k5 blazer reads from empty to 1/4 tank, now matter how full it is, I replaced the sending unit, and the new one does the same. if I ground the sending unit wire it reads empty, and if I leave the circuit open, it reads full. help!!
The entire fuel gauge system relies 100% on good grounds, and you have a bad one somewhere. Our next step would be to run a dedicated ground wire to the gauge itself and another dedicated ground to the sending unit.
On this I thought my sending unit was bad. Because I would fill the tank and it would say around 1/3 to 1/2 tank. I replaced the sending unit because it was old and rusty and had to put a new tank in. But now my tank is full and will only read a 1/4. Im going to assume that my gauge is bad but im not sure and don't know how I can fix it.
If the gauge is bad you probably can;t fix it, you'll have to replace it. However, we suggest pulling the gauge out and bench testing it as we did in this video just to confirm prior to going and buying more parts. Use your own sending unit for the bench test so you can eliminate any issues with that at the same time. Good luck!
Jesus, Like the fuel sender that uses a variable resistance with the float arm, you temperature gauge uses a NTC-thermistor sealed inside a metal canister, it is solid state and start out high resistance then goes low as it heats up. Clean grounds at the engine, run a ground from the end housing of the alternator to the engine or battery. Make sure there is a ground from the engine to the cab. The original is under the right front cab corner in strap form. If the other gauges work fine (Other than oil), but with key on-engine off, disconnect the temperature sensor in the drivers front cylinder head. It is a single wire. When off, the gauge will think the engine is cold and move to cold. Connect this wire to jumper to ground and it should move to hot. If the gauge does not sweep completely, remove the instrument cluster and use the inexpensive test light and long jumper to the battery. This testing can be done with jumper cables but be careful with B+ end. Tape it to the steering wheel. If you connect the test light to power, you are testing for grounds. If the negative, the test light works for positive. The 194 bulb inside the test light will limit amperage to 1/4 amp. Clean connectors. If you remove the connector from the instrument cluster, clean the copper terminals gently with scotchbrite. Use dielectric grease sold for $5 at home improvement stores in the automotive area. Boat dealers use it on all connectors. Petroleum jelly can be used but keeps the copper clean from oxidation exposed to the air. Remember, these are over 50 years old. Hope this helps! NOTE; I would prefer you make fused jumper wires. Radio Shack sold black and red meter wire. Order online with fuse holders, 5 amp-10 amp fuse best and solder your alligator clamps. If using tape instead of heat shrink tubing, place a dab of weather strip adhesive on the end, it won’t unravel. Good luck! ASE Master Tech since 1978
@@BROTHERSTruckPartsTV Brothers, what plugs into the female plug at the bottom of the steering column, is it those 2 plugs ?? I got this truck and it is all jacked up.wiring wise!!
@@kellybergin1532 Depends on the color of the wires in that plug. Not familiar enough with every model year variation to try and give direction without at least know the wire colors.
My fuel gauge on my 71 Nova only will show between 1/2 to 3/4 full when tank is full. Replaced with new sending unit when I replaced the fuel tank with a new one. Have lowered tank and removed sending unit and had a buddy work the float up after down and checked the resistance also while I watched the fuel gauge. We put everything back together, still the same results?! Could the ground to the body be the problem?! Thanks in advance!!
If you had the sender out and tested/watched the gauge work as it should using the cars wiring and NOT a bunch of jumpers to make it happen, then we would rule out a ground problem. However, if you were using jumpers for the test then you need to test the wiring to make sure there is nothing wrong with the wire going from the sender to the gauge. IF THAT CHECKS OUT, then we'd say you've got something inside the tank interfering with the float and causing it to have limited movement.
@@BROTHERSTruckPartsTV Thanks guys!! I have had a few others saying the same hypothesis. Sorry it wasn't on a classic Chevy pickup. Different vehicle yet the principal is the same I guess! Lol!! I do have an old Chevy truck too!!
Hi Dave! Long story short...I tried to buy a beater for my son and apparently accidentally bought a classic. Can you do a video about how to delete the evap canister and what to reroute? He has a 1985 Silverado. The truck wont start since we removed it.
@@BROTHERSTruckPartsTV i ground the gauge then with my test light that has 12V Is touched to one of the post on the gauge it will sweep to full slowly, if I reverse my set up it will sweep empty slowly
When everything is hooked up the gauge will accurately show empty for both tanks. But will never show above a 1/4 tank. I have the sending unit hanging outside the tank to test accurately. I've also replaced both sending units and chased and checked every wire.
1986 c10 new fuel tank and sending unit but my fuel gauge only moves to quarter of tank. I rebuilt the instrument cluster. Is there an adjustment to the fuel gauge the do or reinstall it wrong?
@@tinocorrea742 if the rheostat on the gauge gets damaged you could have the gauge only work to a certain point and then stop. Does it sit there for a long time when you fill up and then start dropping when your tank gets low, or does it act normal but just doesn't go all the way up anymore?
Excellent video , I put in new gauges,sending unit,tank,wiring and I’m baffled that my gauge only reads half full went tank is full. When gauge reads 1/4 I have a half of tank on 1955.1 first series ,235 ci ,3 on the tree. The sending unit read 30 ohms before I installed it.
I have a 71 Chevelle I pulled the fuel tank and replaced the sending/float unit because the gauge would stick on fuel. I noticed that the stop tabs for fuel and empty were bent off to the side. When I pushed the float all the way up past the fuel tab it would stick there. So when I installed the new sending unit I did not bend the tabs. Now when the tank is full the gauge read between 3/4 and 1/2. Once the fuel gets down between 3/4 and 1/2 then the gauge works. Any ideas on what’s wrong?
How many grounds am i looking for. 86 Chevrolet Silverado jusy one tank on drivers side. My fuel gauge reads full the whole time till it is almost out then it goes down to just before e mark. Any suggestions thanks
If it reads full until it's almost empty then drops, it's almost 100% your sending unit that's bad. A faulty ground would never drop the gauge regardless of how much gas you have. Here's a link to replacement sending units for your truck: www.brotherstrucks.com/Sending-Units/products/2507/
Thank you for the information I replaced a fuel pump in a 1987 r10 Chevy it reads fine and drives perfect but I run out of gas when it reads 1/4 tank at least that’s what the gauge says.. would you think this is a gauge issue or sending unit?
Probably the sending unit or a ground problem. test it like we did in this video by removing the wire from the sending unit and connecting straight to ground and see what the gauge does then.
I have an 87 truck with dual tanks. fuel gauge always shows the drivers side tank fuel level ( accurately). when I switch tanks it actually switches tanks fuel wise. but the gauge stays on the driver side tank level. Can you point me to trouble shoot this one.
it sounds like you have no switch connected to the signal wire from tank two. These tank senders are simple 1 wire units, so you'll just have to trace down the wire for tank two and see where it goes and if it's connected to your switch.
@@BROTHERSTruckPartsTV The Senders from the tanks are on switched terminals A & C of the Valve. They each read an Ohm value 0-90 depending on the fuel level. From there, does terminal B supply the info from either sender directly to the Gauge? I get confused with terms here. I call the motorized Pollack valve the 'Valve" and the AC Delco dash switch the "switch". It looks like the switch tells the valve which Tank valve, return line, and Sender to use. but the switching of all three happen in the valve. I will see if terminal B on the valve has the Ohm Value of terminal A or C. and if it changes when the switch on the dash changes. If I have this correct. It seems the pollack valve is switching the fuel lines and Return lines but not the sender information. Confirming or correcting me would be a big help.
@@joeengel5132 to be honest, we don;t have a ton of experience with these valves.switches either. We would do EXACTLY what you are doing by testing the B value to see if it has the A & C values correctly. We'll try and gather some additional info on this as well and report back here if we find anything.
@@BROTHERSTruckPartsTV Just following up on this. I did figure it out. this is the correct operation for a 1987 Square body with dual tanks. (The Senders from the tanks are on switched terminals A & C of the Valve. They each read an Ohm value 0-90 depending on the fuel level. From there, terminal B supply the info from either sender directly to the Gauge) Thanks.
Hey there, I'm curious about something. I have a 91 Chevrolet Silverado R3500, last year of the squarebody heavy trucks, and I just got it back from the mechanic after they replaced both fuel pumps on the truck. When I sent it in the fuel gauge worked and about 5 weeks later, the gauge doesn't work! They said "oh it's the cluster because the oil gauge reads 400 lbs"! Sounds to me like they broke something and don't want to fix it! What would your thoughts be?
My fuel gauge for my 84’ C10 will go past the F, then somehow shoot down to half a tank in a day when i’ve only driven 5-6 miles. would that be the ground, sending unit or something else?
Sounds like the sending unit is going bad. You could provide it a good solid ground for a few days and see what happens before pulling the sender to test it.
Question? Is it safe to have 14.2 volts coming through the firewall into my gauge cluster? I just replaced my voltage regulator thinking that was the issue and still have 14.2. On my old dodge D150 it has a separate voltage regulator on the gauge cluster but still have voltage issue on my volt gauge
I put a fuel injection pump for a 80's chevy truck new, in my 1977 k20 tank and gauge wont register, any help are fuel gauge different ohms? Any help thanks. Aftermarket fuel injection, truck runs exceptional but no fuel in tank and i have put 12 gallons in tank
I have a dual tank 86 GMC High Sierra and having 3 fuel problems . Problem #1 , every time I go to fill up either gas tank it starts clicking like its full and it takes forever to fill my gas tanks. # 2 it at times it leaks from the fuel tank selector valve in which I replaced not too long ago & continues to leak. #3 I think I got this one squared away by watching your video on this problem of grounding and not reading right .
On #1, all Squarebodies suffer from the same dilemma, no solution for that at the moment. Regarding #2, not sure here, but we would suspect a cheap replacement valve. Try and find an AC Delco replacement. #3, nice work! Glad we could help.
I own a C20 ´72 SuperCamper in more or less mint condition. I ran into one problema. Fuel Gauge always shows about 20% too much fuel capacity. So if tank is fully filled gauge exceeds to the right. On a 3/4 filled tanked it shows full and so on. 100% grounded it points to Zero fuel what would be right. i am pretty sure, that i measured around 110 OHMs on an almoust full tank. Any ideas how to fix this. With ignition turned off gauge is showing 55% filled. This seems to be independent of fuel level. Greetings from Germany. BTW: It is a pretty hard job the buy spares in Germany. Will you do international shipping
Yes we do international shipping. For your problem we suggest removing the sending unit from the tank and bending the stop tabs on the internal rheostat until it reads 95ohms full and 5ohms empty. the tabs are easy to bend and this will adjust the sweep of the float in the tank.
Start by checking the ground at the tank, if you ground it and still only get 1/8 then you have a bad wire or a faulty gauge. Otherwise its the sender.
I had a question i have 75 K5 Blazer. Im trying to order a new printed circuit. When ordering a printed circuit there are different options. One of them being without gauges or with gauges. Im trying to understand the meaning of it. I do have the fuel gauge on the right, speedometer, voltmeter, oil pressure, temperature gauge and at the bottom left its a warning light or brake light. Which printed circuit to order?
I have recently replaced my '77 k10, with a '77 c10. (got wrecked) the fuel gauge in the wrecked truck was always steady, but the one in the "new" truck tends to "bounce" as the fuel sloshes around in the tank. any ideas what's going on?
Most analog gauges have a damper on the movement of the needle, sounds like the damper on the "new" gauge is weak or broken. We've seen the same thing with Tachometers before.
@@jgreco137 Both tanks or just one? Does it have dual sending units or does one tank pump into the other? Have the grounds been tested as shown in this video? Lots of possibilities still, but that's why we made this video. If you've checked everything as shown the problem should be obvious already. Providing you have 12 volts of power, there's really only 3 things that can be bad, ground, sender or gauge. Since you say it shows 1/4 tank then we would assume it has 12 volts.
I just found your video and before I take it to a mechanic just wanted to know your thoughts. My fuel injectors or the things that show gas into the carburetor seem to be goin bad maybe. Sometimes when I sit idle for too long or I’ll crank the truck up and gas isn’t coming out of them. What do you think the issues may be?
Looking for help with upgrading the 4 way fuel switch controls for 72 K1500. The trend back then was adding the two side aux tanks. The switch has stopped allowing fuel to flow from either side tank.
We've never messed with that system before, although we've had a number of requests to look into it. We've only heard of some aftermarket replacement switches which don't sound overly reliable. If we had a truck nearby to play around with that had the dual tank setup that would be ideal, but unfortunately that's not the case. We'll keep looking for a donor, but until then we won't be much help.
@@kellybergin1532 Contact our shop or DM us on Instagram and lets see if we can set something up. We have lots of people that try to figure our Dual Tanks, so maybe this is an opportunity to do a video that will help people with these issues.
Dave, do all C10's gauges come with resistors, oil, temp, fuel, battery. Can bad resistors give you false reading or no reading. Please advise. I'm trying to get my 1980 C10 back on Road. Any info would be greatly appreciated. Thanks Robert one more question, Dave . The porcelain resistors are in the back of the gauges correct? Now are they a part of the problem that the gauges don't work.? Or do you need the porcelin resistors to get the gauges to work. It's been a long day and I'm tired. Please help. Everything works except the gauges. "My gauges, Are 40yrs old"
Yes many gauges have resistors, and they need to be GOOD for the gauges to work. However, if all your gauges are NOT working then you likely have a ground problem or your cluster isn't getting 12v power.
@@paulabzotte432 So disconnect the wire from the sender and see what happens next. If you don't get any movement then it could be a couple things... either there's a bad ground at the dash itself, or you have no 12v power to the gauge. Out of curiosity, does your temp gauge work?
I relocated my fuel tank in a 1965 Chevy truck. I used a 80's K5 Blazer fuel tank that uses a 90 ohm sender. Does anyone make a 90 ohm replacement gauge for 1964 - 1966 gauge cluster? or does anyone make a 30 ohm replacement sender that fits a 80's K5 Blazer tank? I see this brought up in tons of forums, but no one has a solution. there are replacement 90 ohm gauges made for other models and years, I just cant find one for 64 - 66. I want to use the stock gauge cluster, so don't suggest some overpriced, ugly, aftermarket gauge cluster.
Couple suggestions... modify the original sender to fit the new tank. modify the new tanks sender with parts from your old one to make it 90 ohms, or... install a completely new universal 90ohm sender assembly in a different spot in the tank. The last suggestion would be our choice. Here's a link to a video we did using our universal tank sender, it's short but you'll get the idea: ruclips.net/video/NQ33sH3unFA/видео.html
@@sixoten Our apologies, we just got 90ohm in our heads and rolled with it. YES you need a 30ohm sender for your '65, unfortunately nobody makes a gauge that fits '65 that is 90ohm, so your only option is to modify the late model sending unit or swap it for a universal 30ohm that will work with the gauge.
You have power hooked up to the clip end of your light tester from the battery when testing the sending unit wire. (Passenger side of guage.)You are checking for a good ground. When testing the power going to the guage, you ground the clip end of the tester on a known good ground and touch the light part to the power terminal on the guage. (Drivers side of guage.) Does that help?
Been fighting my gas gauge not working in my 84 C10 6.2 diesel. After watching this video, I added a ground directly from the fuel gauge ground to a screw on the cab metal and that fixed everything! So glad I came across your video! Thank you!
Our pleasure!
That was truly an expert explanation. Thank you for taking the time to make this video, I am building a ‘64 C10 with my daughter and her fuel gauge stopped working, I am confident that we can fix it now, thanks again!
Dave did an excellent job in this video. Gauges and Sending units seem to be mysterious in some fashion but simple in reality.
A gauge is best described as that experiment in high school science class winding insulated wire around a nail. When connected to a battery, it becomes an electro magnet.
Now, imagine a gauge as a nail on one side wired clockwise, it pushes a paper clip away. A second nail is wound counter clockwise and attracts the paper clip. Now if both nails shared a common ground, a variable resistors, changing the strength to ground makes one side push or become weaker. Same here, except it is inside a gauge. So basically reverse polarity if you can imaging, the common point to ground is a wire wound resistor to ground. In this case, 90 to 0 ohms resistance. If at 45 ohms, both nails have the same push/pull, so the gauge reads? 1/2 full! You got this. As Dave did, placing the lead to a good ground will push the needle completely one direction.
(Imagine one nail is strong and the other is dead) The different is at the sender.
Dave made another good point, that's using dielectric grease on connections. Under the truck? You bet! On the cluster connector, sure! It keeps them clean and not green as copper traces oxidize. They slip in and out better as well, saving that printed circuit on your gauge cluster. Thanks Dave! Good info for those in town and around, the world! Keep em going folks!
DK, ASE master since 1978.
❤
fantastic tutorial and exactly the kind of information needed for me to trouble shoot my old 50 model chevy gas gauge. Very well done. Thanks.
Another great video . Thank you . I have a 1964 c10 , 1965 C10, 1979 C30 pickup, & a 1998 C2500 (454). Love your presentations . Great job.
Thanks for watching! You're really going to like the 1965 C10 "Transformation" series of vids we're about to start shooting. Keep an eye out for them later in 2022 or subscribe and you'll get notified when new stuff drops!
Thanks David now I know where to start. Thanks again
Our pleasure!
Nice video. When testing my sender wire at the guage, the tester light was dim. It had continuity but must of been compromised along the way. Replaced the wire and now is all good. Thanks!
Very good, you explained everything good, I have a 66 C10, I have replaced Guage, new sending unit, still not working, I will recheck all grounds again, thanks this helps me alot, I watch all your videos.
Glad it helped
Thanks. Your straight forward video is great. Fixed my ‘84 k-20. Had to trace after I replaced tank and removed switch over for non existing tank.
Excellent, glad we could help.
You guys are fantastic I buy everything for my 53 chevy truck from you. This video was an incredible help in me figuring out my gas gauge problems. I recently converted my truck from 6 volt to 12 volt and I am installing a gauge reducer to my gauges. Do I need one, not only for my gas gauge, but also for my battery gauge. Thank you for all your informative videos
Yes, voltage reducers for all the 6v original gauges.
straightforward, to the point. Excellent. No Fluff or nonsense, very well done
Thanks for the feedback!
Dave thanks for the video, just changed to EFI on my big block 69 c10 restto- mod. Been fighting with my gas gage for a week. You made it so simple. Fixed after watching your video in about 20 min.
Nice! Thanks for the feedback.
What was you issue that got solved?
@@philup6274 it was not properly grounded. I used rubber washers installing the fuel tank, what happens you over think something. Removed the rubber washers. Working perfectly now. Thanks again
For whatever reason my gas gauge stays high until I hit the brake. When I hit the brake the gauge balances out to the amount I actually have. I’m gonna take a look at it tomorrow after watching this though. Great video man!
Never heard of that one before! Good luck.
Hey Michael, did you ever figure it out?
Thanks this is the best explanation for me.
Glad to hear that!
Thanks. Was having trouble with my 78 blazer.
Our pleasure!
That's a g. D video but I need to know how to get my 93 GMC truck spee0dter to work with my 1973 motor and transmission
Thanks Dave ,you're awesome
Very informative thanks.
Thanks for the help Brother.
Our pleasure!
I have dual tanks. Gauge works correctly when switched on LH tank. But when you switch to RH it’s empty (but it can have a full tank).
Probably a ground problem, but you need to test the sender to figure it out.
Great video David, thank you
Our pleasure!
Hi David, I took some ohm reading's on my sending unit on my 53 Chevy pickup, I'm reading on empty 18 ohms and full I'm reading 52 ohms. I'm thinking that's not good. When on an early Chevy you said, it should be 30 ohms when full. My guage reads a little less then half when tank is full of gas. When I remove wire off the sender and ground it to itself the guage goes lower. It don't ping to full. Not sure if I have a bed sender unit, and a bad guage. Can you please answer that, it would be great to get this gas guage to work again. Thank you
I have a 1988 gmc sierra 1500 4x4 just bought it the previous owners replaced the fuel pump and sending unit , the guages on cluster does not read looks either empty or nothing any help where to start looks like the ground has been moved
First thing you need to do is actually find out of the gauge is missing and add the ground back, then see what happens.
Fantastic video brothers. You got me in the neighborhood. For whatever reason my 85 S-10 goes through gas pumps every so often. I'm on the 3rd or 4th one. Early on mos prolly ethanol. Haven't run that in years and the last one is holding good. But after the last round the gauge is just wonky. Might show half full and then flop over to full, depending on the slosh. Did we put the sending unit in backwards? It's all over the darn place but never shows what it should. Ground? Backwards? The bed is coming off soon so I can get to a short rubber line that is currently spewing gas when the pump is on. Failed at the clamp. (The thing is beyond antique. Ha!) While I'm there thought I might as well see to the gauge. Suggestion? I thank you!!
Norm
Yep, check everything you can while it's apart and easy to access. Thanks for watching!
I have a 12V Gauge. It reads past full when the sending unit isn't even connected. Can you please make a video on how to wire it? This truck was given to me so I do not have the directions.
This is almost always caused by a lack of a 12v source of power to the gauge. The gauge will just drift higher and higher, even well beyond full. Make sure your gauge is getting a 12v power source.
I have a 76 Chevy Nova. The gauge reads full all the time. As soon as power is applied the gauge moves to full. Can I test the resistor behind the gauge before pulling the sending unit?
That typically indicates that you have no 12v power at the gauge. The dash should have a 12v source that supplies the gauge with power. Check that first.
I got a Chevy 350 in my class c RV and the fuel gauge went out last year...seems like I would have to drop the tank to get to the ground wire in the sending unit?
It's possible, they don't always make it easy.
Is gauge failure a common problem? I'm running out of things to check, my trucks a 56.
check out our more recent video about fuel gauge troubleshooting. Maybe you'll see something in it you didn't see here. Gauge failure is always a possibility too, however its easy to check and eliminate that as the issue normally.
Hey Dave i have an issue with my 1986 chevy silverado on my gas gage a full tank and the gage reads 3/8 on both sides i replaced sending unit on one side both sides grounded good
Sounds like you have either a bad fuel gauge or a bad 12v power supply to the gauge itself. Did you happen to hook up the new sending unit and test it while it was out? It would be interesting to hear what happened if you did.
I have a '71 chevy. There is no ground on the fuel sending unit, is it supposed to have one? Currently the fuel gauge just shows the needle in about the 3 o'clock position. Is it not having a ground going to be an issue? I've seen in other videos where it doesn't have one.
The sending unit needs to be grounded. Once you have a ground you can troubleshoot further if necessary.
I have the same problem right now in my 70 c20. No ground on the sending unit. Gauge reads past full all the time.
My power wire is reading 8.4 volts. Only when it leaves the firewall from the fuse box. On the grey wire that comes from the relay reads 12.2. Any idea of what makes it short out? I have went along the wiring and see no visual grounding. It's a 1990 K5 blazer. Running a wire to bypass pigtail directly to fuel pump wire for now.
Could be an internal short in the power lead, or a bad connection at the fuse box.
@@BROTHERSTruckPartsTV thank you for the response I will look into the fuse box! That's where I'm losing the power at. I have 12v on the grey wire at the fuse. 8.4 on the red wire coming back out of EcmB fuse
What side of the terminals does the power go to on the gauge for the cluster is it the terminal on the full side of the gauge and the ground on the empty side
so my k5 blazer reads from empty to 1/4 tank, now matter how full it is, I replaced the sending unit, and the new one does the same. if I ground the sending unit wire it reads empty, and if I leave the circuit open, it reads full. help!!
The entire fuel gauge system relies 100% on good grounds, and you have a bad one somewhere. Our next step would be to run a dedicated ground wire to the gauge itself and another dedicated ground to the sending unit.
Thanks for the content
On this I thought my sending unit was bad. Because I would fill the tank and it would say around 1/3 to 1/2 tank. I replaced the sending unit because it was old and rusty and had to put a new tank in. But now my tank is full and will only read a 1/4. Im going to assume that my gauge is bad but im not sure and don't know how I can fix it.
If the gauge is bad you probably can;t fix it, you'll have to replace it. However, we suggest pulling the gauge out and bench testing it as we did in this video just to confirm prior to going and buying more parts. Use your own sending unit for the bench test so you can eliminate any issues with that at the same time. Good luck!
My temp gauge pegged out. Single wire I believe. Bad sending unit or something with the cluster assembly?
Could be a couple things. Bad sender, bad ground. Start by testing the ground.
Jesus, Like the fuel sender that uses a variable resistance with the float arm, you temperature gauge uses a NTC-thermistor sealed inside a metal canister, it is solid state and start out high resistance then goes low as it heats up. Clean grounds at the engine, run a ground from the end housing of the alternator to the engine or battery. Make sure there is a ground from the engine to the cab. The original is under the right front cab corner in strap form. If the other gauges work fine (Other than oil), but with key on-engine off, disconnect the temperature sensor in the drivers front cylinder head. It is a single wire. When off, the gauge will think the engine is cold and move to cold. Connect this wire to jumper to ground and it should move to hot. If the gauge does not sweep completely, remove the instrument cluster and use the inexpensive test light and long jumper to the battery. This testing can be done with jumper cables but be careful with B+ end. Tape it to the steering wheel. If you connect the test light to power, you are testing for grounds. If the negative, the test light works for positive. The 194 bulb inside the test light will limit amperage to 1/4 amp. Clean connectors. If you remove the connector from the instrument cluster, clean the copper terminals gently with scotchbrite. Use dielectric grease sold for $5 at home improvement stores in the automotive area. Boat dealers use it on all connectors. Petroleum jelly can be used but keeps the copper clean from oxidation exposed to the air. Remember, these are over 50 years old. Hope this helps! NOTE; I would prefer you make fused jumper wires. Radio Shack sold black and red meter wire. Order online with fuse holders, 5 amp-10 amp fuse best and solder your alligator clamps. If using tape instead of heat shrink tubing, place a dab of weather strip adhesive on the end, it won’t unravel. Good luck!
ASE Master Tech since 1978
I got a new sending unit and checked it like you did, and it didn't go to 90 like yours did, 1975 Chevy Cheyenne K10 350
What did it go to?
@@BROTHERSTruckPartsTV Fuel gauge
@@BROTHERSTruckPartsTV Brothers, what plugs into the female plug at the bottom of the steering column, is it those 2 plugs ?? I got this truck and it is all jacked up.wiring wise!!
@@kellybergin1532 Depends on the color of the wires in that plug. Not familiar enough with every model year variation to try and give direction without at least know the wire colors.
@@kellybergin1532 We meant what OHMS did it go to? If not 90 then what?
I bought a c10 with dual tanks. Looking for a dual tank setup
My fuel gauge on my 71 Nova only will show between 1/2 to 3/4 full when tank is full. Replaced with new sending unit when I replaced the fuel tank with a new one. Have lowered tank and removed sending unit and had a buddy work the float up after down and checked the resistance also while I watched the fuel gauge. We put everything back together, still the same results?! Could the ground to the body be the problem?! Thanks in advance!!
If you had the sender out and tested/watched the gauge work as it should using the cars wiring and NOT a bunch of jumpers to make it happen, then we would rule out a ground problem. However, if you were using jumpers for the test then you need to test the wiring to make sure there is nothing wrong with the wire going from the sender to the gauge. IF THAT CHECKS OUT, then we'd say you've got something inside the tank interfering with the float and causing it to have limited movement.
@@BROTHERSTruckPartsTV Thanks guys!! I have had a few others saying the same hypothesis. Sorry it wasn't on a classic Chevy pickup. Different vehicle yet the principal is the same I guess! Lol!! I do have an old Chevy truck too!!
Hi Dave! Long story short...I tried to buy a beater for my son and apparently accidentally bought a classic. Can you do a video about how to delete the evap canister and what to reroute? He has a 1985 Silverado. The truck wont start since we removed it.
If the gauge sweeps slowly toward full and doesn't return when hot wired is the gauge bad?
What do you mean by hot wired?
@@BROTHERSTruckPartsTV i ground the gauge then with my test light that has 12V Is touched to one of the post on the gauge it will sweep to full slowly, if I reverse my set up it will sweep empty slowly
@@BROTHERSTruckPartsTV I took the gauge out of the cluster
When everything is hooked up the gauge will accurately show empty for both tanks. But will never show above a 1/4 tank. I have the sending unit hanging outside the tank to test accurately.
I've also replaced both sending units and chased and checked every wire.
@@philup6274 Yes, it sounds like you have a bad gauge then.
1986 c10 new fuel tank and sending unit but my fuel gauge only moves to quarter of tank. I rebuilt the instrument cluster. Is there an adjustment to the fuel gauge the do or reinstall it wrong?
There's no adjustment, something is wrong. Bad ground, bad sending unit, bad gauge... start by checking all the grounds and the 12v power to the dash.
@@BROTHERSTruckPartsTV I checked unit, ground I believe it's the gauge on the cluster. Now that remember hear d a little pop noise. Thanks
@@tinocorrea742 if the rheostat on the gauge gets damaged you could have the gauge only work to a certain point and then stop. Does it sit there for a long time when you fill up and then start dropping when your tank gets low, or does it act normal but just doesn't go all the way up anymore?
When I fill up that where it stops. It moves down just not all the way full.
@@tinocorrea742 but WHEN does it start to move down? right away, or after you burn through 3/4 of the tank?
Excellent video , I put in new gauges,sending unit,tank,wiring and I’m baffled that my gauge only reads half full went tank is full. When gauge reads 1/4 I have a half of tank on 1955.1 first series ,235 ci ,3 on the tree. The sending unit read 30 ohms before I installed it.
Sounds like you need to start testing your grounds again. What happens when you ground the wire on top of the sender directly to a good known ground?
I have a 71 Chevelle
I pulled the fuel tank and replaced the sending/float unit because the gauge would stick on fuel.
I noticed that the stop tabs for fuel and empty were bent off to the side.
When I pushed the float all the way up past the fuel tab it would stick there.
So when I installed the new sending unit I did not bend the tabs.
Now when the tank is full the gauge read between 3/4 and 1/2.
Once the fuel gets down between 3/4 and 1/2 then the gauge works.
Any ideas on what’s wrong?
Sounds like the tabs are blocking the float from moving all the way to the top
@@BROTHERSTruckPartsTV
That’s kinda what I was thinking but no one said anything about bending the tabs
How many grounds am i looking for. 86 Chevrolet Silverado jusy one tank on drivers side. My fuel gauge reads full the whole time till it is almost out then it goes down to just before e mark. Any suggestions thanks
If it reads full until it's almost empty then drops, it's almost 100% your sending unit that's bad. A faulty ground would never drop the gauge regardless of how much gas you have. Here's a link to replacement sending units for your truck: www.brotherstrucks.com/Sending-Units/products/2507/
Thank you for the information I replaced a fuel pump in a 1987 r10 Chevy it reads fine and drives perfect but I run out of gas when it reads 1/4 tank at least that’s what the gauge says.. would you think this is a gauge issue or sending unit?
Probably the sending unit or a ground problem. test it like we did in this video by removing the wire from the sending unit and connecting straight to ground and see what the gauge does then.
BROTHERS Truck Parts awesome thanks for the help!
I have an 87 truck with dual tanks. fuel gauge always shows the drivers side tank fuel level ( accurately). when I switch tanks it actually switches tanks fuel wise. but the gauge stays on the driver side tank level. Can you point me to trouble shoot this one.
it sounds like you have no switch connected to the signal wire from tank two. These tank senders are simple 1 wire units, so you'll just have to trace down the wire for tank two and see where it goes and if it's connected to your switch.
@@BROTHERSTruckPartsTV The Senders from the tanks are on switched terminals A & C of the Valve. They each read an Ohm value 0-90 depending on the fuel level. From there, does terminal B supply the info from either sender directly to the Gauge? I get confused with terms here. I call the motorized Pollack valve the 'Valve" and the AC Delco dash switch the "switch". It looks like the switch tells the valve which Tank valve, return line, and Sender to use. but the switching of all three happen in the valve. I will see if terminal B on the valve has the Ohm Value of terminal A or C. and if it changes when the switch on the dash changes. If I have this correct. It seems the pollack valve is switching the fuel lines and Return lines but not the sender information. Confirming or correcting me would be a big help.
@@joeengel5132 to be honest, we don;t have a ton of experience with these valves.switches either. We would do EXACTLY what you are doing by testing the B value to see if it has the A & C values correctly. We'll try and gather some additional info on this as well and report back here if we find anything.
@@BROTHERSTruckPartsTV Just following up on this. I did figure it out. this is the correct operation for a 1987 Square body with dual tanks. (The Senders from the tanks are on switched terminals A & C of the Valve. They each read an Ohm value 0-90 depending on the fuel level. From there, terminal B supply the info from either sender directly to the Gauge) Thanks.
@@joeengel5132 Excellent info, hopefully we can do a video on this at some point that will help others that are having troubles like yours. Thank you!
Hey there, I'm curious about something. I have a 91 Chevrolet Silverado R3500, last year of the squarebody heavy trucks, and I just got it back from the mechanic after they replaced both fuel pumps on the truck. When I sent it in the fuel gauge worked and about 5 weeks later, the gauge doesn't work! They said "oh it's the cluster because the oil gauge reads 400 lbs"! Sounds to me like they broke something and don't want to fix it! What would your thoughts be?
My fuel gauge for my 84’ C10 will go past the F, then somehow shoot down to half a tank in a day when i’ve only driven 5-6 miles. would that be the ground, sending unit or something else?
Sounds like the sending unit is going bad. You could provide it a good solid ground for a few days and see what happens before pulling the sender to test it.
Question? Is it safe to have 14.2 volts coming through the firewall into my gauge cluster? I just replaced my voltage regulator thinking that was the issue and still have 14.2. On my old dodge D150 it has a separate voltage regulator on the gauge cluster but still have voltage issue on my volt gauge
14.2 is fine.
I put a fuel injection pump for a 80's chevy truck new, in my 1977 k20 tank and gauge wont register, any help are fuel gauge different ohms? Any help thanks. Aftermarket fuel injection, truck runs exceptional but no fuel in tank and i have put 12 gallons in tank
I have a dual tank 86 GMC High Sierra and having 3 fuel problems . Problem #1 , every time I go to fill up either gas tank it starts clicking like its full and it takes forever to fill my gas tanks.
# 2 it at times it leaks from the fuel tank selector valve in which I replaced not too long ago & continues to leak. #3 I think I got this one squared away by watching your video on this problem of grounding and not reading right .
On #1, all Squarebodies suffer from the same dilemma, no solution for that at the moment. Regarding #2, not sure here, but we would suspect a cheap replacement valve. Try and find an AC Delco replacement. #3, nice work! Glad we could help.
Where does the power wire go to on gauge on the e side of gauge
How did you get power to the cluster
We used the power lead on the circuit board and just attached a battery to it using a clip on electrode.
I own a C20 ´72 SuperCamper in more or less mint condition. I ran into one problema. Fuel Gauge always shows about 20% too much fuel capacity. So if tank is fully filled gauge exceeds to the right. On a 3/4 filled tanked it shows full and so on. 100% grounded it points to Zero fuel what would be right. i am pretty sure, that i measured around 110 OHMs on an almoust full tank. Any ideas how to fix this. With ignition turned off gauge is showing 55% filled. This seems to be independent of fuel level.
Greetings from Germany.
BTW: It is a pretty hard job the buy spares in Germany. Will you do international shipping
Yes we do international shipping. For your problem we suggest removing the sending unit from the tank and bending the stop tabs on the internal rheostat until it reads 95ohms full and 5ohms empty. the tabs are easy to bend and this will adjust the sweep of the float in the tank.
Whats it mean when my gauge on my 56 won't read any higher than 1/8 no matter how much fuel i have?
Start by checking the ground at the tank, if you ground it and still only get 1/8 then you have a bad wire or a faulty gauge. Otherwise its the sender.
Ok thanks much
I had a question i have 75 K5 Blazer. Im trying to order a new printed circuit. When ordering a printed circuit there are different options. One of them being without gauges or with gauges. Im trying to understand the meaning of it. I do have the fuel gauge on the right, speedometer, voltmeter, oil pressure, temperature gauge and at the bottom left its a warning light or brake light. Which printed circuit to order?
I have recently replaced my '77 k10, with a '77 c10. (got wrecked)
the fuel gauge in the wrecked truck was always steady, but the one in the "new" truck tends to "bounce" as the fuel sloshes around in the tank.
any ideas what's going on?
Most analog gauges have a damper on the movement of the needle, sounds like the damper on the "new" gauge is weak or broken. We've seen the same thing with Tachometers before.
@@BROTHERSTruckPartsTV what would you say if the gauge only reads 1/4 full even with a full tank ? - '77 K10 with dual tanks
@@jgreco137 Both tanks or just one? Does it have dual sending units or does one tank pump into the other? Have the grounds been tested as shown in this video? Lots of possibilities still, but that's why we made this video. If you've checked everything as shown the problem should be obvious already. Providing you have 12 volts of power, there's really only 3 things that can be bad, ground, sender or gauge. Since you say it shows 1/4 tank then we would assume it has 12 volts.
Where did you connect the positive wire off the battery?
We connected it to one of the posts on the back of the gauge as seen @ 1:48 in the video.
Ok, I see that, but you have wires running under the cluster so i'm confused
@@kellybergin1532 those wires are just random jumpers we were using for the demonstration.
I just found your video and before I take it to a mechanic just wanted to know your thoughts. My fuel injectors or the things that show gas into the carburetor seem to be goin bad maybe. Sometimes when I sit idle for too long or I’ll crank the truck up and gas isn’t coming out of them. What do you think the issues may be?
Have you tried running a fuel injector or carburetor cleaner though it? They are pretty effective for clearing buildup from the injectors and jets.
@@BROTHERSTruckPartsTV I haven’t can you suggest some?
@@kartezcuby4690 We use the heavy duty one by Lucas Oil.
Looking for help with upgrading the 4 way fuel switch controls for 72 K1500. The trend back then was adding the two side aux tanks. The switch has stopped allowing fuel to flow from either side tank.
We've never messed with that system before, although we've had a number of requests to look into it. We've only heard of some aftermarket replacement switches which don't sound overly reliable. If we had a truck nearby to play around with that had the dual tank setup that would be ideal, but unfortunately that's not the case. We'll keep looking for a donor, but until then we won't be much help.
@@BROTHERSTruckPartsTV u want to fix mine it has dual tanks 1975 K10 4x4??
@@kellybergin1532 Where is the truck located?
@@BROTHERSTruckPartsTV it's in Orange County, California, I thought you were in Corona California
@@kellybergin1532 Contact our shop or DM us on Instagram and lets see if we can set something up. We have lots of people that try to figure our Dual Tanks, so maybe this is an opportunity to do a video that will help people with these issues.
Dave, do all C10's gauges come with resistors, oil, temp, fuel, battery. Can bad resistors give you false reading or no reading. Please advise. I'm trying to get my 1980 C10 back on Road. Any info would be greatly appreciated. Thanks Robert one more question, Dave . The porcelain resistors are in the back of the gauges correct? Now are they a part of the problem that the gauges don't work.? Or do you need the porcelin resistors to get the gauges to work. It's been a long day and I'm tired. Please help. Everything works except the gauges. "My gauges, Are 40yrs old"
Yes many gauges have resistors, and they need to be GOOD for the gauges to work. However, if all your gauges are NOT working then you likely have a ground problem or your cluster isn't getting 12v power.
Where does the power go to on the cluster Dave is it the full side terminal or the empty side
my gauge works but goes pass full and then runs out on full can any one tell me whats wrong
Unfortunately I toke my truck to a shop ,and they couldn't fix for me. Hard to find good mechanics.
..great!
Hey David my gas gage reads 3/8 with a full gas tank 1986 silverado can you help thx
Have you done the tests as I've shown here in the video? If not, I'd start with making sure you have a ground, and then move on to the sending unit.
@@BROTHERSTruckPartsTV yes David i grounded the tanks nothing changed thanks for responding back
@@paulabzotte432 So disconnect the wire from the sender and see what happens next. If you don't get any movement then it could be a couple things... either there's a bad ground at the dash itself, or you have no 12v power to the gauge. Out of curiosity, does your temp gauge work?
@@BROTHERSTruckPartsTV ok ill try this my temp gage works but my oil gage only works when its cold after a little stops working
My gauge is a 4’ stick with notches carved into it….its no fun.
Must be a REALLY old car.
I relocated my fuel tank in a 1965 Chevy truck. I used a 80's K5 Blazer fuel tank that uses a 90 ohm sender. Does anyone make a 90 ohm replacement gauge for 1964 - 1966 gauge cluster? or does anyone make a 30 ohm replacement sender that fits a 80's K5 Blazer tank?
I see this brought up in tons of forums, but no one has a solution. there are replacement 90 ohm gauges made for other models and years, I just cant find one for 64 - 66. I want to use the stock gauge cluster, so don't suggest some overpriced, ugly, aftermarket gauge cluster.
Couple suggestions... modify the original sender to fit the new tank. modify the new tanks sender with parts from your old one to make it 90 ohms, or... install a completely new universal 90ohm sender assembly in a different spot in the tank. The last suggestion would be our choice. Here's a link to a video we did using our universal tank sender, it's short but you'll get the idea: ruclips.net/video/NQ33sH3unFA/видео.html
@@sixoten Our apologies, we just got 90ohm in our heads and rolled with it. YES you need a 30ohm sender for your '65, unfortunately nobody makes a gauge that fits '65 that is 90ohm, so your only option is to modify the late model sending unit or swap it for a universal 30ohm that will work with the gauge.
I'm an idiot.none if this makes any sense to me. It's lighting up on ground and positive?
You have power hooked up to the clip end of your light tester from the battery when testing the sending unit wire. (Passenger side of guage.)You are checking for a good ground. When testing the power going to the guage, you ground the clip end of the tester on a known good ground and touch the light part to the power terminal on the guage. (Drivers side of guage.) Does that help?
Key on when testing power side.