Man do I need some direction and help. I just bought an 84 vette project car (has been setting up for 5+ years). It has several issues which I will need some help on one at a time. For now, I cannot figure out why I am not getting fuel to the injectors. I have checked the fuel pump and it is working when I hot wire it (I get fuel to the carbs but nothing comes out the injectors). However,the fuel pumpdoes not come on with the key switch, only when hot wired. I was "told" to look for the fuel relay. From looking in a couple of purchased repair manuals I found it to be behind the ECM. Only problem is, it looks like a circuit board and not a "relay". How do I check if it is good without replacing? Also, could it be something else as to why I am not getting fuel through the injectors and the fuel pump not coming on? I know the car runs when I pour fuel direct into the carbs.
Also, I had the engine turning over with the key switch. Now, for some reason, it does not turn over nor does it sound like the starter is engaging. Where do you suggest I begin or could it be related to the fuel problem? For some reason I am concerned about whether or not the ECM is working correctly. Is there a way to diagnois the ECM?
I appreciate any help with troubleshooting my problems.
Tim

 

First thing to do is verify fuses. The 84 has throttle body injection, not carbs. Unplug an injector, turn key on on and see if there is power on 1 side of the harness. The fuel pump relay is probably not your problem, since it and the injectors are controlled by the ECM. That is why I wanted you to check power and continuity on all fuses 1st.

 

I unplugged and checked all fuses. Did not see any blown. I unplugged one of the fuel injectors to check power. I do have power on one side of the harness going to the injector with the key on.
By the way, I really appreciate the help and guidance.

 

any additional suggestions?

 

Well the next thing involves using what is called a noid light. You need to get one that fits GM throttle body injectors. Plug it into the injector harness and watch while cranking engine. If it flashes while cranking, then either the injectors are stopped up or you are not getting your fuel supply to the throttle bodies. If no flash, and have power to them, then either the ECM has no power or it is trash, or it is not receiving a pulse signal from the distributor pickup coil. Does the car have spark? Check these things then get back to me.

 

Well, I discovered something. Don't know if it matters but, since I am a new owner....... My car is an '82 not an '84. Now that is cleared up. I will get a noid light and get back to you.

 

Is your 82 a Cross Fire injection? If it is, then GM had lots of probs with early Cross Fires, mainly ECM's, because they were mounted in the battery compartment. []You know battery acid and fumes don't mix with electronics.

 

Also, an 82 is a C3, not a C4.

 

Thanks, yes, I figured that out today on the C4 vs. C3. You can tell I am new to this. Also, should I start this forum over in the C3 forum? (your oppinion is appreciated)
Lastly, yes, mine is cross fire injection and the ECM is in the battery compartment.
Is there a way to check to see if the ECM is bad? I have checked and replacement is around $100. However, if it fixes the problem that is cheap. Let me know if you think I should change this forum to C3. Again, many thanks!

 

If you have powers and grounds to the ECM and no injector pulse or fuel pump, most likely the ECM is bad. Make sure and pull the prom out of the old one to use in the new one. Also, does it have spark?