98 GTP losing fuel pressure

[fro10987]

Originally Posted by bnaylor

Also, note that we have 33# (Called 36#) rated fuel injectors in a GTP. If one or more is flaky like stuck open it will definitely cause a fuel pressure drop and the engine stalling. Just another area to look at just in case the FPR is found OK. Good luck!

If this was the case wouldn't the car run rough or at least put out some black smoke? Is there any easy way to tell if the injectors are working properly?
I ordered a FPR and it will be in the store Mon PM so I will stick that in there say a blessing/prayer the give er a turn. Will either post my joy or sorrow afterward.

[7futures]

Originally Posted by fro10987

Congrats 7future glad to hear you are running


I am still up on the blocks I did replace the evap line set that I broke the "t" in and am still in the same place. Car primes good and will start but then starts dropping fuel pressure till it chokes off and dies. If I pump the pedal the fuel pressure increases then starts dropping again.
I wonder if I connect a positive inside the tank and add a ground if that will help

I suppose my next step is the FPR (fuel pump regulator) any secrets to changing this puppy. I eyed it pretty closely and did not see any fittings that look as if they disconnect. I figure once I have the new one I will be able to figure it out, but any help is appreciated.

!!!!!!!!!FOR SALE CHEAP!!!!!!!!!

1998 Pontiac GTP 135,000 , RED with grey leather, BRAND NEW FUEL System
needs love to run

Hi there Fro10987, Did you ever jump the resister wire like bnaylor suggested? It looks like the low windshield level senser wire because it came from the harness and then went below the washer tank. It looks like a long white connector that you see when you pull out the pass. head light assm. Just jump the wire connector that comes from the harness. I'll pray for you

[fro10987]

Originally Posted by 7futures

Hi there Fro10987, Did you ever jump the resister wire like bnaylor suggested? It looks like the low windshield level senser wire because it came from the harness and then went below the washer tank. It looks like a long white connector that you see when you pull out the pass. head light assm. Just jump the wire connector that comes from the harness. I'll pray for you

Jumping the resistor and bypassing the relay are one in the same.

I replaced the FPR and still the same old same old
I do not think I have injector stuck open as when I turn the key off my fuel pressure does not bleed down and if there were an injector open I would think this would cause the pressure to bleed off once the key was turned off.

I have even went as far as swaping the original fuel pump back in o see if maybe I had a bum pump but both pumps do the same thing. and as I stated before I believe my original problem was mainly with the crankshaft position sensor.

ANY NEW IDEAS or do I buy some lube and take her to the dealer

[BNaylor]

Originally Posted by fro10987

Jumping the resistor and bypassing the relay are one in the same.

I replaced the FPR and still the same old same old
I do not think I have injector stuck open as when I turn the key off my fuel pressure does not bleed down and if there were an injector open I would think this would cause the pressure to bleed off once the key was turned off.

I have even went as far as swaping the original fuel pump back in o see if maybe I had a bum pump but both pumps do the same thing. and as I stated before I believe my original problem was mainly with the crankshaft position sensor.

ANY NEW IDEAS or do I buy some lube and take her to the dealer

What a bummer! I did not believe the FPR was your problem based on the symptoms but you had to rule it out. Question: What is the lowest fuel pressure reading you are getting at the time of problem?

[fro10987]

The fuel pressure declines steadily from startup of 44psi and at about 10 psi the car will die. this is in amatter of about 3-5 seconds. As I mentioned though if I pump the accelerator the pressure will increase to between 40-60 psi depending on how hard I hit the gas.

[BNaylor]

Originally Posted by fro10987

The fuel pressure declines steadily from startup of 44psi and at about 10 psi the car will die. this is in amatter of about 3-5 seconds. As I mentioned though if I pump the accelerator the pressure will increase to between 40-60 psi depending on how hard I hit the gas.

So it is dropping to a low of 10 psi. It is a head scratcher because it sure sounds like a fuel pump resistor problem less the pressure going back up when you pump the accelerator. Providing that all wiring is confirmed good and all components in the fuel pump circuits are OK about all I can think of is the PCM module itself. It does control the switching. Also, you might consider checking wiring between the PCM and back to the two relays in the engine compartment fuse box. Is the PCM stock and have you ever had any work done on it?

[fst100]

did you do the bend pin 85 trick to see if u can bypass the fuel pump resistor?
goto here for a pic
http://www.scacgp.com/mods/fuel_fix/relays.jpg

[BNaylor]

Originally Posted by fst100

did you do the bend pin 85 trick to see if u can bypass the fuel pump resistor?
goto here for a pic
http://www.scacgp.com/mods/fuel_fix/relays.jpg

He claims he did but used the one in the following link.

http://rmcgp.clubgp.com/fpresistor.html

It worked for the other guy that posted here and had the same problem. One down, one to go.

[fst100]

he could try this one, just bend the pin, no need to add another wire on there

[fro10987]

now Im confused. both diagrams show jumping a different relay. I did not try bending the pin on relay #15 which is the fuel pump speed relay. I did bypass the #14 relay by jumping a wire from #30-#87. Do I need to try again???

[BNaylor]

Originally Posted by fro10987

now Im confused. both diagrams show jumping a different relay. I did not try bending the pin on relay #15 which is the fuel pump speed relay. I did bypass the #14 relay by jumping a wire from #30-#87. Do I need to try again???

Both procedures will give the same result by determining whether the fuel pump resistor is bad. But bending the pin on relay #15 is the easier of the two procedures. Also, you can bypass the resistor directly as mentioned by the guy (7futures) that found his problem if you've already removed the headlamp or starting looking for it. The resistor mod calls for moving it from under the fender area to the engine compartment.

Try it again to rule out human error.

BTW - Remember either fix is just a temporary remedy. The fix is to get a new fuel pump resistor. It is not a good idea to run the fuel pump in high speed all the time. The low speed circuit has a purpose to allow excess fuel that is not needed back into the return system back to the fuel tank.

[fst100]

wouldnt hurt to try it. why not?

[fro10987]

Originally Posted by fst100

wouldnt hurt to try it. why not?

I am willing to try anything at least a couple of times. I will try bending the pin on the relay #15 (fuel pump speed relay) and see if that does it.
I did take out the headlight already but I did not see any thing other than lighting wires. I will have to look again I even put it up on the lift and looked from the bottom still did not see it. is it behind the washer fluid bottle?

[fro10987]

I tried bending the pin #85 over and the car actually ran for a minute. I will pick up a new resistor tommorrow and put it in. I cant believe I botched that bypass. When I did that I ran a jumper wire from #30 to #87 on relay #14.
Is a resistor from autozone sufficent or is this one of those that needs to be a high quality item?

[BNaylor]

Resistor is by the washer bottle. Why did it only run for a minute? Or did you turn it off?