ok, just bought an 88 iroc z with a 5.7 tpi, guy tells me the fuel pump needs to be replaced, because it wont start without using engine starter fluid, but once its started it runs fine. now i have changed the fuel filter, new plugs, new distributor. the timeing is rite, and im stuck it randomly starts up fine but still dosnt want to start every time pleeease help me!

 

Sounds like a fuel pump to me.

When you turn the key on.(NOT START, just to the acces. position) You will hear the pump prime for 2-3 seconds. Do that a few times. See if you hear the pump every time. Wait about 10sec. between cycling the key.

If its an original pump Its a good idea to replace it anyways.

 

Sounds like the pump relay is shot or it's not getting energized. No priming, no fuel. Only when the engine is running 12V is also supplied by the oil pressure switch. your engine is running on that now.

 

I agree - fuel pump relay

 

 

I just changed the relay and the pump is cutting on an priming. If it was a fuel pump problem then wouldnt it just not start at all? Or could it not be pumping enough pressure to start it but just enough to keep it running? It doesnt have any power problems when i stomp down on it. When its running it sits there and purrs like a kitten on steroids. I just tried an ignition coil and it still wont crank.

 

I just put a ignition module on it still nothing. fuel pump is i putting out 40 psi. I realy dont know what to do now.

 

So, so far we have a new fuel pump relay, distributor cap, rotor button, plugs, ignition module, throttle pos sensor, 40 psi fuel pressure, compression is good, good fire. Could the fuel pump just be binding at times dropping the fuel pressure instead of not going completely out. Anyone ever heard of them doing that???

 

Have you tried bypassing the oil-pressure switch yet?
also check the grounds for the fuel injectors at the back of the heads.

 

Fuel pump is in, no change . Now leaning toward MAF or computer. And no have tried to bypass.

 

Too bad I didn't see this earlier, I could've said it couldn't be the pump but I'm too late. I'd check wiring to the relay next.

 

Now we have noticed the air temp sensor at the breather is not plugged in and the wires are nowhere to be found, was wondreing if anyone could let us know where it feeds back into the harness, prolly at the MAF wiring but not sure.

 

Someone else posted about Temp Sensor on breather, answer is that breather is for a v6, 88' 5.7L TPI doesn't use that air temp sensor location. That sensor wouldn't be connected to the MAF because the MAF doesn't need to sense air temp to determine the mass of air entering the engine.

If the fuel relay is faulty the engine would only crank longer before starting, but it would start, unless the fuel pressure switch is also faulty.

If you have 40 psi while cranking it's not the fuel pump.

If starter fluid gets it going and stays running, injectors are not initially enabled. A noid light should confirm this, no light while cranking means injectors are not enabled/firing for whatever reason.

No distributor pulse reference signal to the ECM while cranking, (or ECM not responding)
will disable the injectors even if the Dizzy is sparking.

I'm leaning towards the ECM, but you said it runs great, and it wouldn't run very well in limp home mode so that throws me back to square 1.

Your not holding it in WOT while cranking are you? That would definitely disable the injectors (clear flood condition)

 

As for the throttle, no WOT during cranking. As for how it runs once it starts, I personally seem to think its all lil ruff, but the guy that started this thread seems to think its running pretty smooth, running rich we agree on, but he says its running pretty smooth. I personally haven't driven a stock TPI Z so i have nothing to compare to. We're gunna try the ECM next I believe. Good thing is he only paid a grand for the car which is actually in good shape othrewise so this trial and error thing hasnt sunk to far in his pocket yet......But I see it coming lol. Thanks for your reply garcia, further encourages me to ECM isuue.

 

just replaced ECM... still nothing... tested all power to the ECM before replacment and it was getting power... had another mechanic look at it and when we hooked it up to the scaner he had the car idled alot better and actually cranked on its own... I am completely lost on this car...

 

Explain, please I thought it was cranking on it's own just not starting.

 

He means starting, where we come up we call cranking-turning over and we call starting-cranking. welcome to south carolina lol.

 

So it's starting on it's own, problem solved, right? if not now I'm lost.

 

Only at times, the times that it wont, a lil starter fluid in the breather starts it.

 

If you can have the following equipment handy when a no-start condition happens (at home of course.)

You may be able to determine which circuit(s) are failing.

1. DVOM
2. Spark Tester
3. Injector Noid Light
4. fuel Pressure gauge
5. 2 warm bodies

Key off, connect:
Fuel pressure gauge to fuel rail.
Noid light & spark tester to cyl #1 injector and plug wire.
DVOM to distributor 4-wire connector PPL/WHT ref signal wire and BLK/RED signal ground wire.

one warm body to turn over engine the other to help watch the signals.

One or more signals will be absent when the engine doesn't start.

 

ok heres the parts list so far....
ECM
fuel pump
ingnition module
pickup coil
tps
fuel filter
spark plugs
distributor cap
rotor button

its getting fuel and fire. its just not starting. checked timing its good. cranks over fine with no binding or anything. now when it does crank it acts like its flooding. could it possibly be the fuel pressure regulator?

 

An '88 TPI set up has a cold start injector. First check that it is being activated. If so, then check that it actually sprays fuel.

RBob.

 

My 88's CSI was not working when I bought it, but it started up just fine, when cold it just took longer to start, but that doesn't mean yours wouldn't act different ly.

Have you checked the Crank fuse?

 

Check your injectors with a multimeter/ohmmeter. My car was having a similar problem where it would only start using starter fluid. Turns out two of my injectors were reading less that 7 ohms!

 

im having the same problem with 1989 iroc 5.7tpi please let me know what u found out thanks