86 Z28 305 TPI. The engine will start when cold, but after it's warmed up and you shut the engine off and try to restart it, it WILL NOT start. You have to spray starting fluid in the TPI to get it started again. We replaced the MAF and module to no avail. The injectors are brand new. Any ideas? Possibly coil? If so, why would it matter if it's hot or not?

Thanks!
Jeremy

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HoustonZ - 1982 Corvette CrossFire
http://groups.yahoo.com/group/ourstuff/files/Vette/

 

3 things to get things going. Air, Fuel, Spark. I am assuming the first you have, ie no air restrictions.

Fuel. When you crank it after running. What is the fuel pressure? Also, when you put a voltmeter across the terminals of the injectors, is it pulsing the injectors?

Spark. Take out a plug boot and stick a fresh plug in it and ground the thread section. What color of spark? Blue or yellow?

 

Because I have seen this several times before, I'm going to say its your ignition module. Here is why:

If you pull a boot off and check for spark, you should have it. If you remove an injector connector and check for pulse, it won't be there. The ECM needs to see RPM input from the ignition module in order to fire the injectors. Well the ignition module has two modes of operation; cranking and run. For some reason, it seems that most of the time these fail, the "cranking" portion of them goes out. So while you are cranking, spark is being produced, but the signal is not being sent to the ECM. Once you spray starting fluid down the throttle body, and allow the engine to get up past 400 RPM, the ignition module switches to "RUN" mode, and the RPM signal starts going to the ECM and injectors start firing.

It sounds far fetched, but I theorized this on the first car like this I came across, and have been able to prove it true on many others. If you do find its the ignition module, stay away from WELLS. They have the life expectancy of a mosquito. And don't forget to liberally apply the special grease they give you over the entire bottom surface of the new module. Good luck.

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Webmaster:SETHIRDGEN
GM Tech
ASE Master Auto Technician + L1
1987 Trans Am: 357ci
Ported TFS heads, ZZ4 cam, headers & exhuast and other go fast goodies
13.53 @ 103.77

 

Thanks HoustonZ for posting my problem.

Since I actually swapped the 305 for a 350 and ran into this problem, I decided to also upgrade the ignition. I have replaced the distributor, ign. coil, module, and ecm, and I still have the same @#$@!# problem. I think there might be a problem in the wiring harness. Does anyone know where I can by an ECM wire harness?

While swapping the 350, I installed new injectors, alternator, starter, water pump, exhaust. It's been at the shop for over 2 months and it still won't start after running for a while. I have to pulse the injectors for it to start! My last resort is to install a switch to do this! Please help!!!!!

 

BTW, when it's not starting, I get a very dim pulse at the injectors.

What do you think about this article?

http://www.asashop.org/autoinc/feb97/techtips.htm

 

When the car is warm and wont start, if you turn th eignition to the on position do you hear the fuel pump prime? Thats my guess cause that happened to me a month or 2 ago. I would spray gas through the throttle body and she would start. Never had a problem when she was cold.

 

Seems this was the same thing GMTech said...



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Mike

'90 IROC-Z, 5-speed, ZZ4, G1 Trick Flows
Moderator SEThirdgen