0 FUEL PRESSURE

Yet another Problem. Sometimes my car will idle fine and sometimes it will stall and just recently it doesnt want to start at all. I hooked up a fuel pressure gauge turned the key and 0psi :eek:. I was wondering where the relay for the fuel pump was before I drop the tank.

no need to drop the tank... trap door that girl! pneumatic sheers ;) no sparks, no risk of cutting fuel lines.. takes maybe 20min.

If I have to get one, which im sure I will, unless the relay is bad or the filter is clogged, which they aren't cause im not that lucky. What brand should I get Airtex, delphi, (Other)

I would use a test light to see if ur getting power to the pump.Probe positive wire on the plug then have someone turn key on.The test light should light up,if it does and your pump isnt running then you know your pump is bad.If it doesnt light up then you know to look at relay,wiring, ect.

To get to the plug I have to drop the tank or cut a hole dont I?

The fuel pump relay is located behind the driver side left kick panel.
http://www.shbox.com/1/fuel_pump_relay.jpg
Also, you can check to the pump itself by bypassing that relay with this lead.
http://www.shbox.com/1/fuel_pump_prime.jpg

If you can narrow it down to the relay, that saves you the hassle of replacing the pump.

I have not done this on a f-body but i would get under car and reach my hand up around the tank to the pump if possible and unplug the connector and try to pull it down enough that you can put a test light on it then test it

Your relay is in the drivers side kick panel but i would bet it isnt your problem. First thing is check the PCM fuse to see if its blown. If its good run straight 12v to the fuel pump test wire located by the the PCM. If your pump doesnt come on from that and the PCM fuse is good its almost certainly the pump.

I just went through all this...shoebox has very helpful pictures of everything

do I just connect the lead to the battery?

you beat me to it

I have not done this on a f-body but i would get under car and reach my hand up around the tank to the pump if possible and unplug the connector and try to pull it down enough that you can put a test light on it then test it


Here ya go if you wanna probe.
http://www.shbox.com/1/fuel_pump_wiring.jpg

yep...I just put a wire from the positive and touched it to the test wire and it came right on.

Thanks guys for all of your help.

I just have one more question. Could the problem with the fuel pump if it is burnt up or isnt supplying the injectors with enough pressure could it cause it to stumble when I put it to the floor. I assume they are 2 seperate problems but it would be nice if they weren't :rolleyes:

well then check your relays, good luck

yep...I just put a wire from the positive and touched it to the test wire and it came right on.


LUCKY :P

I say start simple and work your self up. Start with checkin the relays then move on to the fuel filter($10) ect...

No luck with the bypass wire.

thanks for the trick though it saved me 10 bucks and wasted time playing with the relay.

No problem....just google "LT1 fuel pump trap door" and there you go. Takes maybe 45 min

no need to drop the tank... trap door that girl! pneumatic sheers ;) no sparks, no risk of cutting fuel lines.. takes maybe 20min.


:thumbsup:

Damn I just redid my interior with new carpet. It has to be easier than going through the bottom though.

Any pump brand that you guys recommend that doesn't require any harness modifications?

I thought you said the pump came on?

I thought you said the pump came on?

No it didnt. It will only come on every once and a while if I let it sit long enough (about every 30-45 mins) and when it does come on it doesnt stay running for long.

Im kind of curious what numbers im getting as far as pressure goes when it does come on though. I think they are low and thats why when I would try to get on it my car would take a shit before it would go anywhere.

No it didnt. It will only come on every once and a while if I let it sit long enough (about every 30-45 mins) and when it does come on it doesnt stay running for long.

Im kind of curious what numbers im getting as far as pressure goes when it does come on though. I think they are low and thats why when I would try to get on it my car would take a shit before it would go anywhere.


I would replace the relay for the hell of it, see if it fixes the intermittent problem. Other than that, a walbro 255 combined with a hotwire kit will work great. And personally, I would drop the tank.

DELPHI OR AIRTEX?

Which is better?

drop the tank x2.

why drop the tank over doing the trap door?

I would double check to make sure that your are getting power to the pump when it doesnt start by testing It like i suggested.good luck

why drop the tank over doing the trap door?

Ive always wondered this myself, maybe unless you just really dont want to cut a hole in your car because other than that there is absolutly no difference in what has to be done.

Ive done several fuel pumps this way in both third and forth gen camaros with never any issues.

replaced a fuelpump in my buds nissian this weekend dropped the tank and crap trapdoor (from the factory) right there, crap at least we diddnt have to drop the axle and I would not have looked UNDER THE BACKSEAT, I second or third the notion cut a door just seal it when your done rtv or something.

The pump seems to be priming itself really slow I was watching the gauge and it goes to 30 and then you can hear it really struggle to get up to 40

I am just wondering why someone wouldnt want to do the trap door when some cars have them from the factory.

How hard is it to drop the axle and how much do I need to lower it if If I dont do the trap door.

Hey Mylt
A friend of mine just gave me a suggestion, Check the lines from the pump to outlet on top on tank, sometimes they split so your pump is pumping gas through the split, back into tank?? I'm going to check mine having a similar problem, (why I been watching thread) and the trap door is cut in mine now, easy as pie lifted carpet and sound deadening mat there it is, really simple. I can get you a pic if you want? although if I had done it would have tried to do it neater, sealed under carpet, no one will ever see it.

When dropping the tack you DONT have to drop the axel.

Wait if you have a cat back i say go with trap door.

The pump seems to be priming itself really slow I was watching the gauge and it goes to 30 and then you can hear it really struggle to get up to 40

I am just wondering why someone wouldnt want to do the trap door when some cars have them from the factory.

How hard is it to drop the axle and how much do I need to lower it if If I dont do the trap door.

you dont have to drop the rear, all you do is saw-zaw the exhaust off, take one of the traction bars loose, and loosten the straps. If your car has the metal fill tube its a royal PITA to do.

Good luck

Hey Mylt
A friend of mine just gave me a suggestion, Check the lines from the pump to outlet on top on tank, sometimes they split so your pump is pumping gas through the split, back into tank?? I'm going to check mine having a similar problem, (why I been watching thread) and the trap door is cut in mine now, easy as pie lifted carpet and sound deadening mat there it is, really simple. I can get you a pic if you want? although if I had done it would have tried to do it neater, sealed under carpet, no one will ever see it.


I cant even hear my pump running half the time the motor is beat

so I jacked the car up today and started probing and could not get any power with the ignition on. So I went to an alternate ground and got a reading of 8 volts. Does this sound right? Now im starting to think that I have a bad ground. My first question is What should the voltmeter be reading and second where would the ground be located?

btw thanks for all your help with this problem.