I have an 86 Vette with 150k miles on it. It was running fine, then became hard to start (hot and cold) now it won't start at all.

I have spark and fuel pressure. The engine will fire if I spray starting fluid in the intake. The check engine light was working now it's not so I can't check for codes (I don't have a scan tool).

I'm thinking of replacing the ECM. Is there something I should check before I do this?

Thanks for the help.

Charlie

 

Check and see if your injectors are pulsing. You can purchase a noid light at any auto parts, unplug the injector, plug it in and spin the engine over. If it pulses, then your computer is doing it's thing, since it gets injector pulse reference from the pickup coil in the distributor. Check your spark plugs to see if they are gas fouled. [8D]

 

Thanks L.B. I'll try to find the light to check for injector pulses.

Charlie

 

you can check for codes my jumping the two top right terminals in the diagnostic port

 

I connected a couple of noid lights and I'm not getting any pulses to the injectors.

I tried jumping the terminals in the diagnostic port to check for codes but the check engine light won't work at all now (it was working before this problem).

Any other suggestions? I checked all the fuses and they're OK. Which wires should I check for power at the ECM? I have the Haynes repair manual but they don't give much detail in this area.

Thanks,
Charlie

 

Does the Check Engine light come on when you first turn the key on? This is a test to see if bulb is good. If it is and you get no codes by shorting terminals, make sure you have power on 1 side of injector harness with key on. If you do, chances are you have ECM problems. If you replace ECM, make sure and pull PROM out of old computer to put in new one. [8D]

 

Since this problem came up the check engine light does not come on at all; when I turn the key on or when I jump the diagnostic terminals. It was working before. I'll check for power at the injector harness as you suggest. Is one terminal on the injectors always "hot" when the key is on and the ground side is used to make the pulses?

Thanks,
Charlie

 

Yes, 1 side is always on the computer controls the ground side for pulse width.

 

I have power to the injector harness so I'm going to try another ECM.

Charlie

 

First check your INJ1 fuse. It powers up the check engine light along with some othe lights on the dash. It should have power across it with key on. If you have power and fuse is good then suspect ECM.