How To Check Fuel Pressure - GM 5.3L V8 (Andy’s Garage: Episode - 147)
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- Опубликовано: 1 авг 2024
- Andy Phillips shows how to locate the schrader valve on the fuel rail of a GM 5.3L V8, and check the fuel pressure. The 5.3L V8 engine was used on many trucks and SUVs, including the Chevy Trailblazer, Chevy Suburban, GMC Envoy, GMC Yukon, Buick Rainier and many more vehicles.
Here are links to other videos of mine pertaining to the Chevy Trailblazer:
HVAC Blower Motor Resistor - Chevy Trailblazer: • How To Replace HVAC Bl...
How To Replace An Alternator - Chevy Trailblazer: • How To Replace Alterna...
Changing Oil & Filter - Chevy Trailblazer: • How to Change Oil - Ch...
How To clean Throttle Body & MAF Sensor - Chevy Trailblazer: • How To Clean Throttle ...
How To Change Brakes - Chevy Trailblazer: • How To Change Brakes -...
Replacing Windshield Wipers - Chevy Trailblazer: • How To Replace Windshi...
How To Remove Wheel Well Liner - Chevy Trailblazer: • How To Remove Wheel We...
How To Replace Upper Control Arm - Chevy Trailblazer: • How To Replace Upper C...
Changing Front Tie Rods - Chevy Trailblazer: • How To Replace Front O...
Wheel Hub Assembly & Bearing Replacement - Chevy Trailblazer: • How To Replace Wheel H...
Brake Booster Replacement - Chevy Trailblazer: • How To Replace A Brake...
How To Replace Spark Plugs & Cables - GMC 5.3L V8: • How To Replace Spark P...
How To Replace Turn Signal Bulbs - Chevy Trailblazer: • How To Replace Turn Si...
How To Replace Side Marker Bulbs - Chevy Trailblazer: • How To Replace Side Ma...
Headlight Bulb Replacement - Chevy Trailblazer: • How To Replace Headlig...
Turn Off Change Engine Oil Light: • How To Reset CHANGE EN...
Fixing Faulty Spare Tire Mechanism - Chevy Trailblazer: • How To Fix Spare Tire ...
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Generally a good video. There is one problem with using teflon tape or any other tape style sealant on a fuel system. It risks breaking free and clogging downstream components. This is why manufacturers and experienced mechanics will tell you this is a fail. IF you must use a sealant then use an appropriate liquid sealant. However, unless the threads are damaged this should not be necessary. Tighten the Schrader valve by hand very snugly. You should not even have to use a wrench or pliers. That is why the connection for the test port is a knurled hand fitting and does not include a hex or other type driven wrench fitting. Use tape and a piece is likely to break free and float around causing you a headache later. This is especially true in fuel injected engines as the tiny atomization ports can clog with particles down to a few microns.
I've used Blue Monster yellow tape in the past and haven't had any issues to date. Not sure if it's recommended but it's what I do. 🤷
It is temporary. Its fine.
Thank u for this video my pressure on my truck is at 40 psi so I'm gonna get a pump tomorrow and replace it
It’s the same for 2000-2007 4.8 5.3 6.0
And the plumbers tape didn’t do anything unless there’s a leak past the threads.
Thank you so much! You just saved alot of grief!
This was GREAT!!!.... Thank you.
👍
Good video great information
My Silverado has 50 psi after replacing the psi reg.
The misfire usually occurs when hot and high humidity will shake your teeth. The idle can be there rough.
Replaced evap solenoid and parts store scanner claimed maf sensor was bad. Nope.
Time for fuel pump
Thank you!
The best way to bleed off fuel pressure is remove the FUEL PUMP FUSE and start the truck. Let it run until it stalls. If it attempts to start but doesn't, try once more to remove residual pressure. Use rags when installing or removing test equipment. When tasks are complete, reinstall fuse. Check for leaks!
Similar to how I run a carb dry on a bike. Turn of the fuel and run it.til it's gone
I would only go through all that if actually removing the fuel pump or filter clearing the rail just for pressure test is fine Otherwise your wasting fuel
Its not so much wasting the fuel. Some crack a line and let it spray. Some drain it in a catch pan. Some let it go to the ground. I prefer letting it bleed off by letting the engine handle it. No matter how its done, it has to be depressurized of any residual pressure to proceed. The environment and safety are priority.
Thankyou bro
May be having t9 replace my, pets hope its filter not pump, fuel filter on my 93 sierra i just picked up. So all of this is good info. Thanks.
Hopefully its not too ridiculous.
Shifts fine but i feel as if im straining it if i go up a big hill etc@@steveallen7742
Thank you buddy 👍👍
You’re welcome
Hey Andy . I wanted to thank you for your time in explaining the pressure gauge hook up process as it is different than the way I had been doing it . I never bled the pressure off of the rail before connecting my gauge . I also want to thank you for saying what the fuel pressure is " actually " supposed to be on these engines . All of the other videos I've watched never announced the pressure . I just replaced my original fuel pump because the truck is a 2000 Chevy Silverado 1500 with the 5.3 in it and the fuel gauge wasn't working properly anymore and the fuel pressure was reading @ 50 psi and would drop down to 49 psi within several seconds . So I bought a " Brand New " AcDelco fuel pump and changed it out , did a pressure test and came up with 52 psi and it would drop down to 50 psi within several seconds . With that being said and going by what you are saying the fuel pressure " should " actually be , it looks like this " New Fuel Pump " could be bad too . The truck was still showing a code P0300 multiple cylinder misfire , so I changed out the spark plugs and the truck ran worse . I more than likely should've changed out the plug wires too while I was at it , just didn't think it needed them until now . Fuel injectors were all showing the same amount of pressure drop ( 17 psi ) when I tested them and the multi-meter test showed they were all getting the same readings , so I think I can rule out the injectors .
Does the pressure stop at 50psi or keep dropping? If it keeps dropping you may need to install an in-line fuel check valve to maintain the pressure, here's a video I did installing one: ruclips.net/video/STIQa1ct_5s/видео.html . The P0300 code is also a random misfire which can be tricky to diagnose. As for the truck running worse; did you gap the plugs properly? Bad plug wires can cause the P0300 as well but you may want to test the wire resistance before replacing them. I did a video on testing the wires, here's the link: ruclips.net/video/am4JlHK1kS8/видео.html . Hope this helps
@@PhillipsVision Thanks for responding Andy . I was wrong with my numbers in the first message to you after the new fuel pump install . The fuel pressure was 50 psi and then would build up to 52 psi within several seconds . At least the new one was building up instead of dropping like the old one was doing . No , the pressure doesn't keep dropping , it stays @ 52 once it builds up from 50 . It only takes a few seconds for it to build up to 52 psi from the 50 psi it initially starts at . The plugs were gapped to .40 as per specs . Also ran some fuel injector cleaner through the fuel rail . Unplugged the fuel pump fuse under the hood , hooked my injector cleaning system to the fuel rail , then started the truck and let it run until the canister ran dry and the truck stopped running . It just seems odd to me that a " brand new " AcDelco fuel pump only raises my psi by 2 , from 50 to 52 psi . I thought the fuel pressure was supposed to be between 55 and 60 psi though ? If that would be the case , my new pump isn't putting out like it should . The truck seems like it's not getting the fuel output it needs . I installed a new fuel filter , new fuel pump , new plugs and wires and the injector testing resulted in a pressure drop of 17 psi on all 8 injectors . However , I don't know if 17 psi is a long enough duration of a pressure spray of fuel per cylinder . If there is anyone out there that has done similar injector pressure drop testing please feel free to share your findings or results .
@@jasond.606 had the same issue wasn't fuel P0300 it was a coil pack.
@@jackhilley6962 Hey Jack . Thanks again for responding . I had a local dealership do a diagnostic check on the truck and they said it showed a P0353 and one for the MAF which is one I set . They also told me I needed a " New ECM " which wasn't on the diagnostic sheet ha , ha , ha - no way they would neglect something like that intentionally , right ? LOL again . Unless they were just wanting to scam me out of $ 800.00 dollars , so I called them on it and of course got some lame excuse .
@@jasond.606 Did you ever find the problem? I had a missfire like that once that ended up being a vacuum leak. Stay away from the dealerships at all cost.
Andy, I have a 2011 Avalanche LS 5.3, my fuel pressure gauge starts at 53psi the drops to 42 psi, I have replaced fuel pump, both knock sensors, map sensor, maf sensor, spark plugs, Catalytic converter is good, the strange thing is I do not get any codes. I am exhausted with trying to correct this issue with poor accelation, it started now a month.
Did you replace the pump with an aftermarket one? Also, have you checked the pressure regulator and fuel filter?
Adelphi unit, regulator good and the filter is in gas tank its a permanent
What's the part number on that fuel pressure test kit !?
THANK YOU!! GREAT VIDEO!!
👍
I have a 2005 gmc envoy. Starts in the mornings but the After I shut it off once, it won’t start. Cranks only. Lately if I let it set for about 5 hrs it will usually start.
you might have an injector stuck open
Mine has 400k. And I’m suspecting it may have a bad fuel pump. Feels weak. But I have 35’s. And the other day. It kept shutting off, and after a few try’s it would turn on for a few seconds and then shut off. After a few of those. It did manage to stay on to drive back home 1/8 mile.
Make sure the pressure is to spec for your vehicle. If not, it could be the pump or pressure regulator
Awesome video! I need help. I am getting a steady 45 psi on my car 2011 suburban 5.3. I feel like its dumping fuel because my fuel gauge goes down more than normal. I see everyone else mention 50 to 60 at the rails but i am using my expensive x431 scan tool to check everything. All of a sudden after 1 month of using e85 its been extremely bad. Fuel gauge drops fast. I cant find no wet fuel leaks by the engine compartment. My mpg normal at 15 to 18. Now feels like 6. I am also using a scan gauge to read the mpgs and its not bad hwy is 18mpg both dash and scan gaugeii. What the hell is there a small leak some where only when its on? Doesn’t throw any codes.
E85 flex fuel 5.3 run at 45 psi from my research lower pressure pumps you can tell if you have Z in Vin
I am having fluttering or stalling sensation coming to stops really bad after restarts. Usually running 34 psi out back. It gets as low as 19 psi sometimes. Starts of at 80 psi sometimes will hold around 55 or 60ish till i start driving for while it will come back down to 34psi. 2021 chevy silverado 1500
Sounds like your pressure regulator, but could also be your pump starting to fail. I would replace the pressure regulator first since it is cheaper and easier to do. If that doesn’t solve it then you need to look at the pump
@Phillips Vision appreciate your time sir. Thanks
What size is that fitting on the fuel rail??
Currently experiencing a crank but no start on a 1999 Silverado 5.3L. It has been sitting for a long time without being used and I recently replaced the battery to start up and get it running again. Tank was empty so I added approx 4 to 6 gallons of fuel and used some starter spray. Engine ran for a few seconds with spray but never stopped after that. Would like to check fuel line pressure with this kit and wanted to know if turning the key to the on position, will the pump create enough pressure to get an accurate reading? Thanks!
I had a similar situation with a vehicle I purchased a few years back. If the vehicle sat too long without being properly prepared for storage, the fuel system could be destroyed. Your fuel pump, regulator and Injectors could be corroded and seized up. Turn the key to the on position and listen for the fuel pump to hum for a couple seconds. If you hear it, then check for pressure. Just turning to the on position will created proper pressure if the pump is fine. If you don’t hear the pump, check to make sure the relay is good. If it’s good then the fuel pump needs to be replaced. Regardless of the pumps performance, if the vehicle still won’t start, check the Injectors since they may be corroded and needing to be replaced as well.
I have a 2018 Tahoe 5.3 and I notice that the needle of my fuel pressure gauge is erratic bouncing around during idle. When I prime it the psi goes up to 80psi. Then 45min later it would drop to 60psi.
Could be the pressure regulator as well
Mines priming at 15psi lets gooo💪💪💪😹
Could someone tell me where the fuel pressure regulator is on a 2010 gmc Sierra 5.3? I have searched RUclips and I can not find out any information.
It's in the gas tank...it's part of the fuel pump...
I have a 2010 Yukon Denali...I was lookn for mine all over RUclips ..no luck..til someone told me....yeah u gotta drop the tank...mine took 2hours..great mechanic...good luck
What would the pressure be for the high pressure fuel pump...?
(I'm.actually looking.a 2017.denali .)
Thanks
55-62 for the 5.3L
@@PhillipsVision ok thanks
FYI - I watched several tahoe fuel pump / fuel pressure videos. I wonder if everyone is misleading viewers. My 2004 Tahoe was running rough & cutting off once in a while. So I changed my fuel pump and rechecked the fuel pressure. I saw a 43-45 psi pressure reading again at idle (wth!). From what your video is saying this is low. But then I disconnected the vacuum line going to the pressure regulator and the pressure jumped to normal 55 psi pressure. I also saw your pressure was around high 40's when you 1st started your Tahoe too. So should fuel pressure should be checked with the vacuum line disconnected?🤔
Try it both ways. It could be a faulty pressure regulator
After filling the tank last night on my 03 4.8 silverado when i went to start it this morning all I got was cranking with no start. I put a fuel pressure guage on and with the key turned to on it doesn't move the needle at all. am I doing something wrong... thanks
Do you hear the pump priming (humming noise for about 3 secs when you turn the key)?
@@PhillipsVision yes I do hear something for few seconds
So...you are getting pressure from the pump but not holding it? Could be the pressure regulator
Thanks I'll check that out next
Hello, I got pressure primed at 58 psi and running at 43 psi plus a P0171 code. Pressure holds well. What could be the problem?
P0171 means you’re running lean (too much air). You might have a vacuum leak
@Phillips Vision I'm having the same issue. What would be a good starting point to check for vacuum leak?
is there two Schrader valves to determine why one fuel bank is leaner than the other
No, just one valve for the fuel rail
So would 34 psi be too low and cause my issue or fuel pressure reg?
What was your problem? My psi is reading about the same as yours.
I just changed my fuel pump and fuel filter on my 2002 5.3 chevy tahoe. I was at 42 psi prior to changing out the pump and filter. I'm still at 42 psi. Could the fuel pressure regulator the fault for having not enough psi as I should?
Yes, could be the problem. Before you change it make sure you have a tight connection at the schrader valve
@@PhillipsVision for when checking the psi? I was using pipe tape on both the Guage connection and the rail connection so I'd imagine there was no leaks. I'm going to change it this morning. After changing the fuel pump yesterday, changing the regulator is nothing lol
@@PhillipsVision it's a flex fuel engine. Does that change the needed psi?
@@mikespence8895 did the regulator fix the problem?
@@rayriley174 no.
2008 gmc sierra 5.3 started truck 45psi and needle jumps 44 45 I think pump is bad
Yes, that’s very low. A new fuel pump and pressure regulator might be needed.
@@PhillipsVision thanks god bless from albuquerque new mexico
I put the gage on my 01 6.0 and ran just like this just under 50 psi. I turned off the truck and lost the pressure right away?
Fuel pressure regulator most likely. Don't rule out leaking injectors, but rich exhaust and misfire will be hand in hand when injectors leak.
@@steveallen7742 how would I test leaky injectors I gotta make sure
I have 35 years in automotive repair and half of those were at GM dealerships. I have swapped maybe 10 injectors on GM products. Swap the module assembly in the tank. I have put in quite a few hundred of them. Easiest way on a pickup is tilting the bed up. Remove 4 bolts on tank side and loosen the other 4 on the opposite side. Remove filler neck bolts, unplug bed harness, remove filler neck ground, get a couple buddies to lift the side and block it ( At least three 6×6 posts cut 20" was our choice) well. Seriously, early Duramax had injector issues. Gas burners were rare as hen's teeth.
@@steveallen7742 I have the 01 crew cab 6.0 4x4 with a 5 speed manual gas it goes any where
@@lowerdesert9577 Take some vise grips and wrap the jaws with tape. Use them to pinch the return line going back to the tank. Key on... If fuel pressure doesn't drop, regulator is fault. If fuel pressure still drops, take a second set and wrap (unless you have hose pinching pliers). Leaving the first set on the return still, get prepared to pinch the inlet line. Key on, immediately crimp inlet hose. If pressure drops injector(s) will be fault (Again, that's unlikely. That fast of a fuel drop can fill a cylinder with fuel and hydraulically lock the engine. You will also find fuel in the oil). If pressure is up and holding, fuel pump module is fault. Make sure the hoses are firmly crimped, but protected. It isn't good to crimp the plastic fuel lines but it won't kill them if protected.
What code did the truck have a P0171 or P0174?
Mel Hardee neither, I was just showing how to check the pressure. P0174 usually pertains to the MAF Sensor
My 2002 gets up to 45-50 mph and starts hesitating what could that be
Could be the camshaft position sensor
So what should my minimum fuel pressure be and when I did my test needle was bouncing from 44 to 49 so 55 is minimal then? Do I need a new fuel pump or can I install a check valve somewhere to help this issue any thoughts from anyone please? Thank you
Sounds like the fuel pump or pressure regulator needs to be replaced. If your vehicle is sluggish when accelerating it is most likely the pump
@@PhillipsVision I rechecked my pressure it was about 54 I was reading it incorrectly I only primed once first time I did a drop test it went down to 40 after about a half hour do you think installing the one way after the fuel filter will help keep pressure better? I changed my fuel pressure regulator recently and fuel filter my fuel pump will probably need to be replaced soon its a 2001 silverado 5.3 v8 with 125000 miles..so just wondering if you think it would help snd what size check valve do I need for my truck? Thank you
@@robertpaul3675 you could try it, put it in-line after the fuel sending unit
@@PhillipsVision did the check valve seemed to help alittle. My fuel pressure is 50 psi with engine running. 55 with battery just on in acsessory mode. Is this below the normal spec?
@@robpaul7900 you’re good then. Key on/Eng off should be between 55-62psi
so, I have a 2002 chevy Silverado, when I turn the key to prime it, it stays at 0, 48 psi running the vehicle, fuel pressure drops to 0 when I turn off the vehicle, anybody else had this problem.
What's the valve with the green cap?
EVAP
Is it normal by over night sitting fuel psi to drop to 0 ? But will hold 52psi for few hours then slowly drop and by over night it’s to 0-5psi
No, it’s not normal. The pressure may go down slightly but if it’s dropping to that level you may have a leak somewhere. Do you have problems starting it in the morning?
@@PhillipsVision no it always starts and runs great , it has a performance 340lph fuel pump assembly .. I took off fuel rail and primed the fuel pump no injectors leaks , checked fuel lines nothing leaking , and it’s a brand new fuel pump whole bucket assembly .
@@PhillipsVision it’s a 2001 Camaro Ss procharger with quantum 340lph fuel pump assembly
I have a 5.3 but it's not the same. I have a 2014 gmc and there is no valve.
This is a 2003. Most newer vehicles are not equipped with schrader valves
With the key on mine drops to 0. What could be causing that
When you turn the key to prime it, it drops to zero?
@PhillipsVision with key on it jumps too 90 psi for a seccond then bleeds off instantly to 0 psi. I cycle it a few times same thing. It will run bouncing around 120 psi some one has osias e85 pump in it. It's just a stock 5.3 swapped obs chevy. I'm thinking new pump? Using thr factory sender. May just grab the whole gas tank form the 02 chevy an make it work
@@ODellGarage731 could be the pressure regulator as well.
Do you have a vidio on automatic transmission on 2005 gmc envoy
Not yet
I have a 2014 Silverado 5.3 and I cannot find the schrader valve to release the fuel pressure and test it. This video isn’t correct for all 5.3 engines or something.
The 5.3L in this video is a 2003. General Motors may have changed it on the newer ones.
My envoy has the 5.3 motor
Have you checked the fuel pressure? Could also be the starter failing.
@@PhillipsVision would it crank if the starter is failing?
@@jamesq8378 no. When Starter fail it won’t crank and you may get a buzzing noise
@@PhillipsVision ok, thank you for all your good information. I bought a fuel pressure test kit. I’ll test it. 55 to 65 correct?
@@jamesq8378 55 -62
Hi!
What size/thread/type of adapter do I need for the schrader valve on the fuel rail?
I bought a fuel pressure tester but the adapters that came along with it didn’t fit the schrader valve.
So, do you know what size/type/thread it is?
I got a 2013 silverado 5.3 it's at 41 psi
Did you fix your problem? I lose presure over night and the pressure is 45 psi but once it gets going it maintains 55.
@@uriel0002 not fixed yet
@@SECRETGOVERMENT2012 dang my only does it when it's 15 Fahrenheit or lower outside. But I got myself an starting fluid just in case also I pump the gas pedal and for some reason it starts.
@@uriel0002 mine stays at 41psi all the time just pulled 1900 pounds with trailer
@@SECRETGOVERMENT2012 I stay at 42 psi. I'm about to change my fuel pressure regulator. I just changed my filter and pump and it's still at 42. Did you get yours up to 55?