Hello everybody, I am posting this for my brother who has a '98 Grand Prix GTP (3.8 Supercharged). The car was hit pretty hard in the front and needed a new front clip (bumper, hood, fenders, windshield, etc...) which he put on and did all of the suspension work at his body shop. Whatever the problem is, he says it was caused by the impact of the crash...(Duh.. the car has to be running to hit something that hard..haha)

OK, to the problem. The car will start and run for a few seconds before it dies. He put a fuel pressure gauge on it to get a reading. When the switch is turned on the pressure will jump to about 50psi and after cranking will slowly fall off to 20psi where it dies (about 10 seconds).

You can feather the throttle (1/2 to 3/4 back and fourth) and keep it running but the whole time it is bellowing black smoke from the exhaust and running like SH*T. If you gag it wide open the fuel pressure spikes to 50-60psi and when the supercharger kicks in it drops to 20 psi and dies. You can crank it and spray ether in it and keep it running but as soon as you stop the engine dies once again.

So far he has replaced the fuel pump and the fuel pressure regulator. I don't think it is leaky injectors because they hold their pressure for a long time. Could it be the vacuum line to the fpr?? He says that the vacuum lines look good.

Sorry for the long post, just trying to give as much info as possible.

Somebody help please!!

 

Anyone???

 

2Fast,

I had a VERY similar experience following an impact (mine was hit while parked).

The fuel pressure would vary a lot, and when I finally got the tank out to replace the pump, here's what I found:



SOMEHOW ¿? it would still make enough pressure to run, but just like "sewage" as you describe...

 

Some cars have a one-time inertial switch (somewhat like the seat belt mechanism in 3rd gens) to disable the FP in case of a wreck... I know F*rd Taurus does, because somebody hit me with one of those once, and it wouldn't run any more because of that... you might want to look in a Chilton's or Haynes or something and see if that kind of car has such a thing

 

Hey thanks for the replies guys. Actually I found out the problem. It is the fuel pump resistor. I took a paperclip and bypassed the resistor by grounding two of the terminals at the relay. It cranked and ran great!!! until we reved it past 4000 rpm and the supercharger kicked in. Now at 4100 rpm and up the engine is cutting back and shaking when it is under boost (looks like the whole thing is gonna jump out of the engine bay, haha). One problem down, who knows how many to go

Thanks again for the replies.

Tony

 

Oh yeah, by the way, that last problem is not the rev limiter if that is what you are thinking. If anyone has any suggestions please post them.

Tony

 

RB,

I don't think GM used those. Most GM cars already have "*****", and therefore don't need the one in the inertia switch (you know, the one that has to be manually reset). There might be some that use them, but none I'm aware of.

FYI - Did you know that most vehicles with H.I.D. headlamps have the same type of switch to short the HV power supply in the event of a crash? And they aren;t resettable, so you get to purchase another $600.00 headlamp power supply if you get in a fender-wrinkler. I'll bet the insurance boys love that just as much as they do these stinking air bags....

 

I'll Be damned