I have a 1988 GTA with the 5.7. lately its becoming harder to start. It doesnt do it all the time, but when its cold, or been sitting for awhile, it will just keep turning over, almost like its out of gas. Once the car starts and I shut it off, it starts right back up. Also first thing in the morning when its cold, after cranking I hear a thump, thump, thump, almost like a air lock, not coming from the engine but almost like near the drivers side fire wall. Also when the engine is at operating temp. and I shut it down I hear a high pitch whine coming from near the fuel tank that goes away if I open the gas lid and relieve the pressure. It seems also lately as the starting problem has increased, so has my rough idle. I have recently changed out the wire, plugs, cap and rotor.

PLEASE HELP

 

Tough one.

Its possible that your air inlet vent for the tank isnt working, that part is under the car near the tank on the driver side, a white piece of plastic about 1.5" in diameter. I have yet to see one of these fail.

It does sound like a fuel related problem. Have you replaced the fuel filter? Also check the rubber fuel lines by the engine, they are from the fuel rail to just about where the alternator sits, make sure they look ok and squeeze them they shouldnt have any weak or soft spots.

 

Agreed. Leaky injector(s) would cause a hard start when the engine has been sitting. Fuel from the injectors has time to saturate the combustion chamber upon shutdown. The engine won't start until the excess fuel has been pushed out of the combustion chamber.

The hard start won't occur upon restarting the car immediately after shutdown simply because the fuel from the leaky injector(s) hasn't had time to soak the combustion chamber.



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Willie

Supercharged 1987 305 IROC-Z, Daily-Driver, Emissions-Legal.
Former Paxton (6-psig): 12.57 @ 111 mph.
Former Paxton (6-psig) & former 50-hp nitrous: 12.04 @ 114 mph.
Current ATI D1SC (Initially 10-psig): Projecting high 11's.
Future ATI D1SC (15-psig): Gotta catch them pesky 26-psig boosted TTA's!!

http://willie.camaro-firebird.org/

1987 "20th Anniversary Commemorative Edition" Z28 Convertible -- Super Chevy Show Class Winner, 1998.

 

If I had leaky injectors would I be able to tell by the colour of my exhaust smoke at startup? The mixture would be very rich at startup if the injectors leaked would it not? Therefore would the exhaust smoke not be black?

 

Not necessarily because the excess fuel in the combustion chamber is not burned. It is literally pushed out the exhaust in a liquid state. That's why the engine won't start. The fuel in the chamber causes the initial air/fuel ratio to be so rich it won't fire until the excess fuel is pushed out the exhaust.

You can conclusively diagnose leaky injectors by pressurizing the fuel system, then blocking off the rubber return hose (the smaller of the two). If the pressure does not sustain itself, you've got a leaky injector(s).

Willie

 

Are you sure that you have spark? Next time it's hard to start take the coil wire off the cap and place it near a piece of metal and crank the engine. If there is spark ignore the rest of this post, if not read on. Unplug the wires at the back of the distributor module for about five minutes and plug them back in. Try starting again, if it didn't work try replacing the module. If it did work however, welcome to my ongoing problem.

I too have a problem with the car being hard to start after it's been sitting for a while (like overnight) that reoccurs every couple of months or so. Originally I just had to keep replacing the distributor module, but finally the parts store got sick of me taking advantage of their lifetime warranty and started testing all of the ones I was bringing back. Every one has tested good. So it seems that my problem isn't the module itself, but that when I unplugged the wires to switch the module it was resetting something else. Unfortunately I still haven't been able to figure out what it is. Since there are only three things directly connected to the module it has to be either the coil (not the problem, it's been replaced), the pickup coil or the ESC module. I'm still trying to determine which of the latter two is the cause of the problem. Hopefully I'll find out soon.

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Black 88 GTA L98
261 RWHP, 345 RWTQ
13.406 @ 103.72 MPH
ZZ4 bottom end, Edelbrock 6085 heads, LT4 HOT cam, GMPP 1.6 RR's, ported stock TPI, SLP 1 3/4" headers, no cat, Dynomax cat-back, Stock PROM
E.T.F.A Member #11