The problem is the OEM factory pumps are known for those check valves to go bad and so Ford made two inline valves (PN Genuine Ford Connector 1L3Z-9J274-BA) to fix this issue. Some people have them and some people don't just depends at the time of the recall if the vehicle was taken in. I had/have this same issue with my 93 f150 with the 4.9 L. I realized very recently that when I had replaced both sending units that I damaged one of the valves on the rear tank (which is my tank that is overflowing). So if you get that part, put it on the return coupling on the tank you're having issues than that should fix it. Recall # is 01l008000.
That was my problem but with both tanks took the bed off install two new pumps, I don’t care I am pushing 75 years old and handicap and took me almost a week to do the job but it works perfect now I can chase that rich widow woman that lives down the street, thanks for the information to do the job
excellent job figuring this out, it makes sense now as to what was going on with my truck that I inherited, my father in law must have had a new fuel pump installed without the check valve, which also overflowed into the charcoal canister and onto the ground.
Thanks very much for the info. I just replaced both pumps on my 94 F150 and my front tank is transferring the fuel to to the rear. My truck doesn’t have the tank selector valve from factory so this must be the problem as you decried. I’ll pull the bed back off and check. The truck will run but only off the rear tank. Fuel is transferring from the front tank only so must be the wrong pump.
Yeah brother.... I'd been there never got the tee shirt and coke deal.LOL, However my license did & are actively suspended for the next 5 years over that day. Wish I knew all this then. Keep up the good info. Be safe
Lol. I did about the same thing for awhile, but the fuel gauge didn't work either on my front tank as well as would overflow if using the rear tank so it was always a guessing game on the front.
So the front tank needs a double check valve. The front tank pump needs a check valve on the inlet to the pump. So that when the front pump is off the ceck valve will stop the backflow through the pump. Same thing on the back tank as well the pump will need to be on the live pressure line like the front one with a valve to block the pressure from the other pump pushing gas back into the tank through the pump. The valve on the pressure side of the pump should open and close to let the return gas back into the appropriate tank if its working correctly on both pumps.
Good video, thanks! To be clear, you only replaced the front tank pump, correct? My ‘94 has the exact same problem. Mine is leaking gas overflow at the filler hose. Maybe I need a new filler hose, that rubber is 28 years old! I will buy an oem replacement pump if they are reasonable and available.
great video but you're off just a little bit, Ford started using the check valves in 90, the issue was they were having was the check valve was bad on the pressure line, Ford's fix was to install a check valve on the high pressure line, so you need to actually check the valves on both lines. and also prior to 90 that would have been a lift pump only doing about 7 lb, the vehicles with the switching valve had a high pressure pump on the rail
Thánks for illustrative video! I have a F150 1989 4.9 lts dual thank configuration, AND lately hace the dame issue with the front thank overflow when rear thank Is in use. The gas spills over the feeding gas hose after a while use of rear thank. So It could be work yo install an external check Valve on one of the thank out hoses? Thánks for your help!!
I have a 95 flareside with a 351 and it just started doing this last night. I got home last night and I can smell gas and it was spilling out from around the front gas tank cap I took the cap off and gas went everywhere my fuel gauge is way past full
Great video! Question: I just replaced rear gas tank which was working; kept everything the same except for tank and filler neck; now car won’t start when I filled her up. Front tank has been unusable, starts up and dies reads empty but rejects gas when I try to fill so I’m not sure if I’m having the check valve issue. I’ve always just used the rear tank and it runs fine. What else could I try to get the car started, I’m going after the schrader valve tomorrow, couldn’t get the cap off
Here's something else i learned messing with the bad fuel pump issue... if you're getting low fuel pressure codes when you replace your pump follow "ford tech makuloco" 's advice and drain the memory on your PCM by jumping your positive battery terminal connected tour battery to your negative battery terminal disconnected from the battery for @ 10 minutes then hook it back up and star yhe engine with everything else turned and let PCM "learn" how to idle t it warms up, then go for a mellow cruise for 10 miles or so and then get it up to highway speed to let your PCM reset your shift points and your fuel trims... it will get rid of any erratic shifting and bad fuel delivery habits the PCM picked up while your truck was throwing codes... it made my truck run and shift alot smoother after I did that !!
I'm having the same issue but on the opposite pump it's overflowing into my rear tank I bought a check valve So I put it on the smaller line going into the front fuel pump correct which direction
I think you kind of got it wrong because my 92 that I have the check valves are on the fuel line they put a check valve on the return line on the rear tank in the front tank and it prevents it from filling up the opposite tank
Ok… but I just replaced my front pump and now when I’m using my front tank my rear tank overflows AND when I’m using my rear tank I’m getting fuel pumped in my front tank..?? So how could both sending units check valves go at the exact same time..??? 1995 f150 4.9 l Eddie Bauer
It may be possible that the rear is just getting worn out and the front one you just replaced isn't the correct one. ( This may seem crazy, but. It's kinda easier to remove the truck bed to get to them if you have a friend or two that can help lift it off. It really isn't that heavy, even an 8ft bed. It's just 4 bolts holding it down, disconnect the filler neck hoses and unplug the wiring harness for the taillights. I did one of mine that way with just one friend helping to lift it up and back off. Sit it on some saw horses.) I had to do one of mine 3 times before I figured out what was wrong. You can blow into both tubes on the pump, you shouldn't be able to blow through them on either of the two tubes going into the pump.
Im having a similar issue with my 95 f350 gas engine. Just put a new front fuel pump and new tank. But gas keeps flowing to the rear tank. The rear fuel pump is bad. It don’t even come on when I flip the switch. Would you recommend replacing the rear pump or would I be better off canceling it. Kinda just want to run on the front tank since it’s new. Thanks.
Yes rear pump is bad. Those check valves I spoke about in the video are leaking, that's why your rear tank is filling up. To stop that without replacing the pump you would have to cap off both lines near the rear tank somehow. Side note: if you plan to replace the pump only and have someone to help you, it is actually easier (in my opinion) to take the bed off, especially if the tank is full, tank gets pretty heavy when its full, plus the connections can be difficult to get to when lowering the tank. The bed is 6 bolts holding in on, the small screws and hose clamp near filler neck holding the filler neck and a couple plugs in the back for the tail lights, have a friend help you lift it off and the rest is cake. Plus you can pump any old nasty fuel out of it at that time if it has been in there for a long time. I have a long bed and it isn't to bad, not as heavy as one might think. Also note when you get the new pump, before you do anything else, blow into both lines on the pump, you should not be able to blow air through either side. If you can it's likely the wrong pump. You can also do that on the old pump and you should be able to see what I'm talking about if you can blow air through it.
can you tell me which brand to buy that has the correct internal check valves for my 1996 f150 5.0l styleside single cab steel 19G side tank? i bought an skp sending unit/pump assembly for $70 and I can blow right through the return pipe on it.
@@jpvjjohnny ok, I thought so, that's the only place I've seen that brand. So it is honestly hard to say. I had the same issue I got the "wrong" pump from Rock Auto and is the one I had shown in the video, which is why I decided to do this video. I would have thought that selecting a 1996 that I would have gotten the correct one from them, but it didn't work out that way. They have so many different brands, it's difficult to be sure you get the correct one. I can tell you that it is very very important to be certain that you get the correct one for the fuel tank size that you have. A 17 gallon pump may fit, but will not sit correctly inside the tank of a 19 gallon tank, or vice versa. If I remember correctly I think I ended up getting a Delphi pump and it was correct. Hope this helps, and good luck, it can be a bit of gamble with them on this one. I use them pretty much for everything, but this one was difficult to figure out on their site.
I replaced the oem pump in my front tank with the SKP pump because the one that was in there had such low fuel pressure and the quantity circuit aways showed empty even if the tank was full to the brim.. now it pumps good pressure and the gas gauge works good, but when i run on the rear tank it dumps fuel to the front quicker than ever... but at least the front tank pumps good so i have to run the front tank down to under half before i can run the rear pump which goes low real quick then back to the front tank til it gets low again, and then only add new fuel to the system in the rear tank. I thought the delphi pumps on there were just the pump body only.. so how do you get the "retainer" (the metal tubes) off of the old pump without breaking something? I figure the front pump will get run alot more with no return line check vave in the pump body, but at least i can figure out my mpg now if i top off the front tank and run it only for 100 miles and then top it off again. Thanks dk Dain your video showed the secret to the trouble... i just wish if you ordered a pump for a 1996 it would be built to match the oem configuration but it is what is... just a quirk a driver will have to learn to work around
If your front tank is over flowing then your front tank pump assembly is malfunctioning/ which contains those check valves. You could test it by blowing low pressure air through both of the lines like I described, if they leak by then the whole assembly would have to be replaced. There isn't really any way to replace or repair the check valves alone.
Unfortunately there is no real way to. Just try blowing into both tubes when you get it, before you even start disassembling anything. You should not be able to blow air through either one
I need your help on the harmonic balancer video I did the same process as you but after re Installing truck won’t fire only cranks. Any advice? Will it not start if I didn’t torque it down enough?
I bought a msd pro billet. Distributor a msd 6al digital box and msd coil after installing truck wouldn't pulse Injectors how do I make this all work I'm seriously about to trash aaall this FI and get a carb please help
@@RollingThunder85 unfortunately without being able to see everything myself, I'm not likely going to be able to help. Aftermarket is almost always a gamble
@@dkdain9002 the old distributor sent a signal to the pcm when to fire the injectors the new distributor doesn't do any of that, what are your thoughts on a FI to carb swap? This is a pulling truck going up and over a small MTN range from Portland to sand dunes I need power not mileage ?
No real way to know the part numbers. They can be different for different brands. No, front and rear tanks are different pumps. They are identified by year and tank size as well as steel or plastic tanks.
A fuel pump is constantly running while the engine is running. Which means that fuel is constantly flowing from the tank to the engines fuel rail (on fuel injection types) and then back to the fuel tank. Basically fuel is flowing in a constant loop. The engine only uses what it needs from the fuel rail as it needs it, higher RMP's need more fuel and less fuel at idle. So in other words "blocking off" the return would over pressurize the the fuel system in that "loop" most likely causing the fuel pump to fail from being over worked from trying to constantly pump fuel that isn't flowing like it should. So no.... I suppose you could on the tank and fuel pump that isn't being used. But I personally would not recommend it.
@@dkdain9002 8i was asking because i was removing my electric pumps for my 12 valve and there were no pumps in the tank. the connector had 4 wires terminated on the outside but only one on the inside, fuel sending unit. works out good for me. Thanks for the response, good video.
@@dkdain9002 no my diesel has what Ford calls a lift pump it operates from the camshaft bolted to the top of the motor... the tank switch has 4 lines in from the 2 tanks, supply and return .. the tank switch then has only 2 lines going to the motor.. supply and return... the tank that is in use is the tank that the fuel from the return line will go to.. .... ..I thought gassers had this same switch.... I would be willing to bet your problem is in the tank switch... it's stuck in the forward tank and only letting fuel return to that tank.. ... there should not be any restrictions on the return line.. if there's a one way valve on the return it probably is to keep fuel from going out through return line...
@@brianturck274 ok. Yeah I am not familiar with the diesel models. The gassers work differently then. The gassers work as I described in the video. Replacing the front fuel pump fixed the issue due to the internal check valves that open with the fuel pressure of the pump that is in use and closes off when that pump isn't running and in use. As I've shown in the video and after disassembling the old pump and comparing it to the new correct pump (not the "new one" in the video) I learned and know now exactly how they work. / my fuel switch works as it should.
I just replaced both my pumps on my 95 and they are filling each other up and causing my gas to run out fast cause they are going back and forth from tank to tank , can anybody give me some advice
@@ebaht7468 I usually use rockauto.com, but you have to be very careful and mindful about which one to get. You have to know for certain what size and type of tank you have, (plastic or steel). The only way to know what size tank you have is either looking it up by the vin or exact model. Or run it dry and fill it up to see how much it takes to fill it up, but I would not advise that if your other tank doesn't work.
The problem is the OEM factory pumps are known for those check valves to go bad and so Ford made two inline valves (PN Genuine Ford Connector 1L3Z-9J274-BA) to fix this issue. Some people have them and some people don't just depends at the time of the recall if the vehicle was taken in. I had/have this same issue with my 93 f150 with the 4.9 L. I realized very recently that when I had replaced both sending units that I damaged one of the valves on the rear tank (which is my tank that is overflowing). So if you get that part, put it on the return coupling on the tank you're having issues than that should fix it. Recall # is 01l008000.
I have same problem my rear thank is overflowing and my truck don run properly but wen I use that from run perfectly fine
That was my problem but with both tanks took the bed off install two new pumps, I don’t care I am pushing 75 years old and handicap and took me almost a week to do the job but it works perfect now I can chase that rich widow woman that lives down the street, thanks for the information to do the job
Same problem and confirmed my hunch as to what’s happening. My new pump didn’t have the return check valve. Thanks for digging into this and sharing.
This video deserves two THUMBS UP 👍 thanks for explaining this is such great detail & easy to understand
Finally. You are the first person for me to Explain that.
Thanks for posting this! Mine is opposite so I will need to replace the rear tank pump cause it fills up when I run on the front tank. Thanks again!
You used a check valve and everything was good?
excellent job figuring this out, it makes sense now as to what was going on with my truck that I inherited, my father in law must have had a new fuel pump installed without the check valve, which also overflowed into the charcoal canister and onto the ground.
Thanks man! Having the same issue and it has been driving me nuts! I will check to see if this is what is going on with my 96 F150
Thanks very much for the info. I just replaced both pumps on my 94 F150 and my front tank is transferring the fuel to to the rear. My truck doesn’t have the tank selector valve from factory so this must be the problem as you decried. I’ll pull the bed back off and check. The truck will run but only off the rear tank. Fuel is transferring from the front tank only so must be the wrong pump.
I have same isue did u fix it and watch was that problem
I have a 91 and need 2 new fuel pumps. Glad to know as the part listings are not clear.
thank you for an excellent instructional video. that is my exact problem i am dealing with
Yeah brother.... I'd been there never got the tee shirt and coke deal.LOL, However my license did & are actively suspended for the next 5 years over that day. Wish I knew all this then. Keep up the good info. Be safe
Which new pump did you use to fix this issue?
My 1995 f150 does this,I just run the front tank to 25% then switch to rear,after 100 miles I fill both tanks and start over on front tank again.
Lol. I did about the same thing for awhile, but the fuel gauge didn't work either on my front tank as well as would overflow if using the rear tank so it was always a guessing game on the front.
So the front tank needs a double check valve. The front tank pump needs a check valve on the inlet to the pump. So that when the front pump is off the ceck valve will stop the backflow through the pump.
Same thing on the back tank as well the pump will need to be on the live pressure line like the front one with a valve to block the pressure from the other pump pushing gas back into the tank through the pump. The valve on the pressure side of the pump should open and close to let the return gas back into the appropriate tank if its working correctly on both pumps.
Thanks for the education! Great video!
Looks like I need to pull noth tanks out and get the right pumps with double valves.
Thank you for sharing..
Good video, thanks! To be clear, you only replaced the front tank pump, correct? My ‘94 has the exact same problem. Mine is leaking gas overflow at the filler hose. Maybe I need a new filler hose, that rubber is 28 years old! I will buy an oem replacement pump if they are reasonable and available.
My front pump was the only one giving me problems, so yes. But it could have the same issue if the rear isn't working correctly
great video but you're off just a little bit, Ford started using the check valves in 90, the issue was they were having was the check valve was bad on the pressure line, Ford's fix was to install a check valve on the high pressure line, so you need to actually check the valves on both lines. and also prior to 90 that would have been a lift pump only doing about 7 lb, the vehicles with the switching valve had a high pressure pump on the rail
Excellent video !
Thánks for illustrative video! I have a F150 1989 4.9 lts dual thank configuration, AND lately hace the dame issue with the front thank overflow when rear thank Is in use. The gas spills over the feeding gas hose after a while use of rear thank. So It could be work yo install an external check Valve on one of the thank out hoses? Thánks for your help!!
I have a 95 flareside with a 351 and it just started doing this last night. I got home last night and I can smell gas and it was spilling out from around the front gas tank cap I took the cap off and gas went everywhere my fuel gauge is way past full
Great video! Question: I just replaced rear gas tank which was working; kept everything the same except for tank and filler neck; now car won’t start when I filled her up. Front tank has been unusable, starts up and dies reads empty but rejects gas when I try to fill so I’m not sure if I’m having the check valve issue. I’ve always just used the rear tank and it runs fine. What else could I try to get the car started, I’m going after the schrader valve tomorrow, couldn’t get the cap off
correct if am wrong the one should hold presiure is the main and no the returnig cause tha dosnt make sense
There's a old Ford recall on this issue
For the love of God PLEASE someone give me a part number for a rear fuel pump THAT HAS THE CHECK VAlve BUILT IN...ive ordered 3 and ALL wrong
How did you fix it??? I got a new and still does it
Here's something else i learned messing with the bad fuel pump issue... if you're getting low fuel pressure codes when you replace your pump follow "ford tech makuloco" 's advice and drain the memory on your PCM by jumping your positive battery terminal connected tour battery to your negative battery terminal disconnected from the battery for @ 10 minutes then hook it back up and star yhe engine with everything else turned and let PCM "learn" how to idle t it warms up, then go for a mellow cruise for 10 miles or so and then get it up to highway speed to let your PCM reset your shift points and your fuel trims... it will get rid of any erratic shifting and bad fuel delivery habits the PCM picked up while your truck was throwing codes... it made my truck run and shift alot smoother after I did that !!
Do you know what actual part to order and where to get it?
I'm having the same issue but on the opposite pump it's overflowing into my rear tank I bought a check valve So I put it on the smaller line going into the front fuel pump correct which direction
I think you kind of got it wrong because my 92 that I have the check valves are on the fuel line they put a check valve on the return line on the rear tank in the front tank and it prevents it from filling up the opposite tank
If that's the case on yours then yours is just different. 91 and older wasn't the same, 92 was a transition year and may have been hit or miss
do you have part number for the correct pump assembly
Sorry, but no.
Ok… but I just replaced my front pump and now when I’m using my front tank my rear tank overflows AND when I’m using my rear tank I’m getting fuel pumped in my front tank..?? So how could both sending units check valves go at the exact same time..??? 1995 f150 4.9 l Eddie Bauer
It may be possible that the rear is just getting worn out and the front one you just replaced isn't the correct one. ( This may seem crazy, but. It's kinda easier to remove the truck bed to get to them if you have a friend or two that can help lift it off. It really isn't that heavy, even an 8ft bed. It's just 4 bolts holding it down, disconnect the filler neck hoses and unplug the wiring harness for the taillights. I did one of mine that way with just one friend helping to lift it up and back off. Sit it on some saw horses.) I had to do one of mine 3 times before I figured out what was wrong. You can blow into both tubes on the pump, you shouldn't be able to blow through them on either of the two tubes going into the pump.
Is not hard to do it I do it miself last year on same truck yea take mi like 3 hours but I did it
Hiw did you fix it tho ?
Can you use just the new pump and install it in the old assembly and make it work?
If those check valves I spoke about are bad, then no. Those are part of the whole assembly
@@dkdain9002 thank you
If the pump on the back tank would it work for the tank in the front cuz I want to cut the back tank out and just have the one single tank black self
I suppose you could, but you would have to cap off the lines going to the back tank
@@dkdain9002 yeah that was my plan just didn't want to take the chance of screwing anything up as far as replacing the pumps
Im having a similar issue with my 95 f350 gas engine. Just put a new front fuel pump and new tank. But gas keeps flowing to the rear tank. The rear fuel pump is bad. It don’t even come on when I flip the switch. Would you recommend replacing the rear pump or would I be better off canceling it. Kinda just want to run on the front tank since it’s new. Thanks.
Yes rear pump is bad. Those check valves I spoke about in the video are leaking, that's why your rear tank is filling up. To stop that without replacing the pump you would have to cap off both lines near the rear tank somehow.
Side note: if you plan to replace the pump only and have someone to help you, it is actually easier (in my opinion) to take the bed off, especially if the tank is full, tank gets pretty heavy when its full, plus the connections can be difficult to get to when lowering the tank. The bed is 6 bolts holding in on, the small screws and hose clamp near filler neck holding the filler neck and a couple plugs in the back for the tail lights, have a friend help you lift it off and the rest is cake. Plus you can pump any old nasty fuel out of it at that time if it has been in there for a long time. I have a long bed and it isn't to bad, not as heavy as one might think.
Also note when you get the new pump, before you do anything else, blow into both lines on the pump, you should not be able to blow air through either side. If you can it's likely the wrong pump. You can also do that on the old pump and you should be able to see what I'm talking about if you can blow air through it.
@@dkdain9002 thanks for the info man. I appreciate it.
can you tell me which brand to buy that has the correct internal check valves for my 1996 f150 5.0l styleside single cab steel 19G side tank? i bought an skp sending unit/pump assembly for $70 and I can blow right through the return pipe on it.
Rock Auto?
yes, i got the skp pump from rock auto ($70)
@@jpvjjohnny ok, I thought so, that's the only place I've seen that brand. So it is honestly hard to say. I had the same issue I got the "wrong" pump from Rock Auto and is the one I had shown in the video, which is why I decided to do this video. I would have thought that selecting a 1996 that I would have gotten the correct one from them, but it didn't work out that way. They have so many different brands, it's difficult to be sure you get the correct one. I can tell you that it is very very important to be certain that you get the correct one for the fuel tank size that you have. A 17 gallon pump may fit, but will not sit correctly inside the tank of a 19 gallon tank, or vice versa. If I remember correctly I think I ended up getting a Delphi pump and it was correct. Hope this helps, and good luck, it can be a bit of gamble with them on this one. I use them pretty much for everything, but this one was difficult to figure out on their site.
I replaced the oem pump in my front tank with the SKP pump because the one that was in there had such low fuel pressure and the quantity circuit aways showed empty even if the tank was full to the brim.. now it pumps good pressure and the gas gauge works good, but when i run on the rear tank it dumps fuel to the front quicker than ever... but at least the front tank pumps good so i have to run the front tank down to under half before i can run the rear pump which goes low real quick then back to the front tank til it gets low again, and then only add new fuel to the system in the rear tank. I thought the delphi pumps on there were just the pump body only.. so how do you get the "retainer" (the metal tubes) off of the old pump without breaking something? I figure the front pump will get run alot more with no return line check vave in the pump body, but at least i can figure out my mpg now if i top off the front tank and run it only for 100 miles and then top it off again. Thanks dk Dain your video showed the secret to the trouble... i just wish if you ordered a pump for a 1996 it would be built to match the oem configuration but it is what is... just a quirk a driver will have to learn to work around
So if my front tank is overflowing while running off the rear tank, would my issue be the check valve inside the front tank?
If your front tank is over flowing then your front tank pump assembly is malfunctioning/ which contains those check valves. You could test it by blowing low pressure air through both of the lines like I described, if they leak by then the whole assembly would have to be replaced. There isn't really any way to replace or repair the check valves alone.
So did you have to replace both the front and rear pumps??
No. Only uses the tank and pump that is in use
Mine is doing that too ( mine is 19 gallon too )........ What pump did you get??
Spectra Pumps seems to be one of the better ones
@@dkdain9002 did the plug of the new pump plug right in or did you have to modify it?? And many many thanks for the reply
@@billbond2045 directly plugged.
@@dkdain9002 thank you and my 96f150 thanks you👌.
They are extremely expensive on eBay a set is 500 dollars
so how do i confirm that my new fuel pump before i buy it has the check valve on it?
Unfortunately there is no real way to. Just try blowing into both tubes when you get it, before you even start disassembling anything. You should not be able to blow air through either one
I need your help on the harmonic balancer video I did the same process as you but after re Installing truck won’t fire only cranks. Any advice? Will it not start if I didn’t torque it down enough?
Does it have an exciter ring on the back?
I don't recall what the torque spec was, but I know it was pretty tight.
I bought a msd pro billet. Distributor a msd 6al digital box and msd coil after installing truck wouldn't pulse Injectors how do I make this all work I'm seriously about to trash aaall this FI and get a carb please help
@@RollingThunder85 unfortunately without being able to see everything myself, I'm not likely going to be able to help. Aftermarket is almost always a gamble
@@dkdain9002 the old distributor sent a signal to the pcm when to fire the injectors the new distributor doesn't do any of that, what are your thoughts on a FI to carb swap? This is a pulling truck going up and over a small MTN range from Portland to sand dunes I need power not mileage ?
@@dkdain9002 ty for the reply
What's the part number on the correct pump and could it be used for both tanks?
No real way to know the part numbers. They can be different for different brands. No, front and rear tanks are different pumps. They are identified by year and tank size as well as steel or plastic tanks.
Example, my 1996 F-150 has a 19 gallon front tank and my 1996 F-350 has a 17 gallon front tank.
Ok cool thanks I appreciate the information
Can you cap off the return and still work?
A fuel pump is constantly running while the engine is running. Which means that fuel is constantly flowing from the tank to the engines fuel rail (on fuel injection types) and then back to the fuel tank. Basically fuel is flowing in a constant loop. The engine only uses what it needs from the fuel rail as it needs it, higher RMP's need more fuel and less fuel at idle. So in other words "blocking off" the return would over pressurize the the fuel system in that "loop" most likely causing the fuel pump to fail from being over worked from trying to constantly pump fuel that isn't flowing like it should.
So no....
I suppose you could on the tank and fuel pump that isn't being used. But I personally would not recommend it.
are those both gassers?
Yes. Although I'm sure the diesel models are the same
@@dkdain9002 8i was asking because i was removing my electric pumps for my 12 valve and there were no pumps in the tank. the connector had 4 wires terminated on the outside but only one on the inside, fuel sending unit. works out good for me. Thanks for the response, good video.
@@dkdain9002 no my diesel has what Ford calls a lift pump it operates from the camshaft bolted to the top of the motor... the tank switch has 4 lines in from the 2 tanks, supply and return .. the tank switch then has only 2 lines going to the motor.. supply and return... the tank that is in use is the tank that the fuel from the return line will go to.. .... ..I thought gassers had this same switch.... I would be willing to bet your problem is in the tank switch... it's stuck in the forward tank and only letting fuel return to that tank.. ... there should not be any restrictions on the return line.. if there's a one way valve on the return it probably is to keep fuel from going out through return line...
@@brianturck274 ok. Yeah I am not familiar with the diesel models. The gassers work differently then. The gassers work as I described in the video. Replacing the front fuel pump fixed the issue due to the internal check valves that open with the fuel pressure of the pump that is in use and closes off when that pump isn't running and in use. As I've shown in the video and after disassembling the old pump and comparing it to the new correct pump (not the "new one" in the video) I learned and know now exactly how they work. / my fuel switch works as it should.
So you need both rear and front to have the valve?
No. The check valves are made into the pump assembly
Yes I get that but do both pumps need the check valve? And so if rear returns to front then rear is bad? @@dkdain9002
I just replaced both my pumps on my 95 and they are filling each other up and causing my gas to run out fast cause they are going back and forth from tank to tank , can anybody give me some advice
Wrong pumps, both. The video explains why
@@dkdain9002where did you find correct pumps ?
@@ebaht7468 I usually use rockauto.com, but you have to be very careful and mindful about which one to get. You have to know for certain what size and type of tank you have, (plastic or steel). The only way to know what size tank you have is either looking it up by the vin or exact model. Or run it dry and fill it up to see how much it takes to fill it up, but I would not advise that if your other tank doesn't work.
This is wrong all these trucks have the check valve that how they build fuel pressure 300 i6 single tank to a 460 dual tank
3 Check valves is 2 to many why they got to make shit so over complicated is beyond me