Hello all..

I recently purchased a 57 Belair with a 87 L98 engine installed. The guy I bought it from had just finished the installation of the engine when I bought it. The motor appeared to run fine with no problems.

A few days later the motor started surging a bit at low rmps especially leaving from a stop sign. It wasnt bad, and I could accelerate through it. My thought was the injectors were prob. a bit dirty so I went to the autoparts store and picked up a bottle of Chevron fuel injector cleaner. I drove the car around for about 45 minutes with no problems. Later that night I took the family out to dinner in the malibu (the restraunt was about an hour away) and just when I pulled in to the place the car died! I waited about a minute and restarted the car, it started ok but then seemed to loose fuel pressure. When I stepped on the gas the car would just stumble and not accelerate.

Ok.. I figured that the cleaner just got a bunch of gunk loose and cloged the fuel filter.. no biggie.. After eating dinner the car started up and made it home (barely) but then died 1 block from the house. We walked home and I went and got the car an hour later. So yesterday I changed the fuel filter, the old one was full of junk. I figured Id solved my problem. After changing the filter I let the car idle for about 90 minutes out in the driveway and low and behold the same problem. The car seems like it loosing fuel pressure. You can tell its starting by the surging, it seems starved for fuel and then seems to get a bit more fuel, the rpms jump up a bit. When I try to give it a little gas sometime I can pull it out of its 'starvation' and get the engine stable again, but eventually it will die. The car will not restart imediatly after this happens but if I let it sit for 5 mins or so it will restart and the problem usually reoccurs after 10 mins or so.

So, Im not sure what the problem is.. there appears to be 3 issues that I can identify:

1. The injector cleaner is screwing something up somehow. Could the filter be cloged again?

2. Something wrong with the fuel pump that causes it to die after 90 mins or so of operation even though I can hear it running.

3. Heat, perhaps the gas is perculating (sp)? Ive driven the car longer in traffic for 2 hours before with no problem.


So Im not sure whats going on.. Id hate to drive the car to the local chevy dealership and pay 100$/hr to have them diagnose the prob..

Anyone have any suggestions at all?

THANKS!!!!
Joe

 

id hook up a fuel pressure gauge and see whats going on,, it should be around 36psi ,, and with the vacuum line off the plenum from the fuel pressure regulator it should be 10psi higher. are you getting any codes? how new is your o2 sensor? it could also be ignition related. may also be maf problem, unplug your maf sensor and see if it runs better.
hope this helps

[This message has been edited by ron rizzotti (edited December 31, 2000).]

 

Update..

Ok heres what Ive found..

I went to Kragens (of all places) and got a pressure gage.. at idle the car runs around 20-25 psi.. then after about an hour of idling the pressure drops to about 10psi and the engine dies..

Trying to restart the car the pressure stays at about 10psi even though I can hear the fuel pump going..

My assumption at this point is that there is something wrong with the fuel pump??

Anyone have any other ideas?

 

I think you've found your problem.

Sounds like the fuel pump is getting hot and giving up.

Time for a fuel pump.

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ASE Mechanic/Machinist/Smog Tech

1999 NBM Trans Am
1986 Chevy 3/4 ton pick up
1981 corvette
1995 Kawi ZX6R

GO #3

 

ACK!!

Ok, I just changed the fuel pump and everything looked ok at first..

Then the same thing started happening again! as soon as the motor got warmed up the pressure dropped to about 15 psi and the motor died..

I wanted to check the electrical connections just to make sure so I ran a lead directly from the battery to the pump with no change, same problem.

Is it safe to assume that its the pressure regulator? Id hate to have to rip off the manifold to replace it..

Thanks!!!

 

Ok.. after alot of yelling and cussing.. I jacked the car back up and blocked off the return fuel line.. pressure shot up to about 70 psi in about 10 seconds.. I shut off the motor because im not sure how high a pressure the motor can take (I dont want to cause anymore probs). Soooo my assumtion based on this test is that the pressure regulator is bad?

Whatcha all think?

Thanks!

PS.. anyone know a good site that walks you through the replacement of the pressure regulator?

 

You still running the stock style tpi regulator? They're cake to change...just unbolt the allen (maybe torx) screws and pull it off. Get an adjustable one and set your pressure to around 45psi to start.

You might also want to try blocking your return line then turning off the motor and watching how fast the pressure drops...you could have leaking injectors.



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87 IROC-Z, 5.7, auto, 3.27, leather, !cat, Holley fpr, K&N'S, SLP 1-3/4" Jet-Hot coated headers, SLP .218/.224 .495/.502 cam, Comp 1.5 roller tip rockers, $uperPITAram, Edelbrock lower intake, Holley 52mm tb, Dynomax\Flowmaster catback. Coming Soon(?)- Fasttrack/Accell DFI

1989 Pontiac 20th Anniversary Turbo Trans Am - 161,000 miles, !cat, 9" K&N

 

Having your pressure jump up after you block the return line usually does indicate a bad regulator. I would've tried replacing the regulator first as it's cheaper and easier than a fuel pump. You can usually get a regulator rebuild kit from a parts place. Napa probably carries them, and they'll usually come with pretty good instructions on how to change it out. Good luck!



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89RS w/350 TPI; 69RS/SS w/450 HP 350/Muncie 4-Speed "Too weird to live, too rare to die."