I have a 92 formula with an aftermarket 383 TPI engine (vin indicates the car originally had a 305 TBI, swap was done before i came into possession). Recently, the engined died while idling and hasn't started since. It will ignite while car starter is sprayed into the manifold while starting, so the spark plugs and all seem to be functioning. Also, there is at least 30 psi at the fuel rails, so the fuel pump seems to be working. However, the injectors do not seem to be firing. Using an automotive stethoscope, i do not hear any of the injectors clicking while the engine is being turned over.

At this point, i'm not sure how else to diagnose the problem. What else would control the injectors firing other than the ecm? Jumping the A and B terminals to get the computer codes gives nothing but the "12" code that the diagnostic system is okay. Should i assume the ecm is bad or is there some other sensor that regulates when the injectors should fire?

I'm not too familiar with ecms or whatnot, what i pulled out from the space above the passenger's feet is a silver box with all the wiring harness connections and labeled:
"Make: GM
Production Number: EM7730
Production Broadcast Code: R7C"

If the ecm is bad, is this what is replaced? or simply a chip inside of it? None of the connections seemed loose or burnt or anything.

I've not been impressed with the workmanship of this engine, it looks like a frankenstein setup, someone had a lot of random engine parts and decided to throw them all onto this car. Much the wiring is a mess of butt splices and electrical tape heh. But something seemed to fail because i had been driving it a couple times a week without engine troubles, had just driven about 20 miles in it, and was idling at my destination for about 2 minutes when it died and never restarted. I'm considering scrapping the TPI and just carburating the whole thing. With that as an option, I'd really like to be more sure of what's actually wrong before attempting to fix (and spend money on) an ecm or whatever might be wrong with it.

Does anyone have any insight on what i might check for? If it is an ecm failure, what would i replace it with? I apologize for the lengthy post, i try to be as descriptive and complete as possible If there is any additional info i can provide to help with diagnostic possibilities, let me know. Thanks in advance for anyone who can shed some light on this for me.

Robby

 

Bump.

Any ideas? Is there anything other than the ecm that could be stopping all the injectors from firing?

Thanks
Robby

 

I know the PCM has to see a RPM signal from the distributor igniton module before it'll fire the injectors. I would check this first since you say all 8 aren't firing. A bad ignition module will definatly keep it from starting but not always keep it from sparking.

 

Cool, I'll check that tomorrow night, thanks for the advice

Robby