I just picked up an 89 RS for a song. I know the previous owner and he has replaced the fuel pump, rebuilt the TBI and put in new injectors. The car will run if you pour some gas into the throttle body, but the injectors don't seem to fire and will not run without the gas pour. The ECM is getting power but the injectors are not. I opened up the ECM and found some obvious failure points. Before I replace the ECM I'm wondering if there is anything else I might check to avoid blowing another. Can I run the diagnostics trick (A&B pin, count the flashes) without an ECM? The car is in pretty good shape otherwise. Only one significant dent, little rust and decent interior. I've worked and modded older cars in the past but this will be my newest project (the wife wants a toy) and also my first Chevy. Thanks in advance for any advice!

 

Jumping pins A&B put the ECM into diagnostic mode to flash codes, etc. It will not do anything without an ECM. Before replacing a damaged ECM, its good to check all ground and power connections to the unit for continuity and to verify no shorts. Also, test injector circuits for resistance. Wire length in the circuits adds some resistance but the readings should be within 1-2 ohms of the injectors themselves. Healthy low inmpedance injectors run about 1.5-2 ohms.

If this 89 has VATS(resistor plug in the key), be sure that the VATS system is working properly. Also, verify crank referrence signal from the distributor to the ECM. Otherwise replacing the ECM will do nothing.

 

Thanks for the info. We just got the car and I've yet to tow it to my garage but I'm pretty sure there was a chip/plug on the key. I'm buying a shop manual and as much other literature as I can find, but I've had great luck on other forums for other vehicles. The ECM circuit board actually has burn marks on it, but the previous owner claims he checked everything for shorts. I'm going to check all the aforementioned electrical stuff before I replace the ECM. What symptoms would a bad VATS give?

*edit* I'll probably ask about that in another thread, sorry