I recently installed a TBI system on my 383. I had the engine running twice now but after warm-up and shutdown, the injectors won't fire when I try to restart. I do have spark and a good reference signal from the dist. However, I checked the voltage on my injector drivers and it drops from 12 volts at "ON" to ~0 volts at "RUN". Also, my crank signal (Pin C9) drops from 12 volts at "ON" to ~9 volts at "RUN". Would low battery voltage during cranking cause the ECM to not fire the injectors?

 

Ok, here's more info. I found that the injector drivers are doing exactly what they are supposed to, switching to ground at "RUN". It looks like my problem is with Pin A1, the fuel pump relay drive. It switches to 12 volts at "ON" to prime the pump and then drops to 0 volts. When I turn the key to "crank", Pin A1 remains at 0 volts. Any ideas? The EST high reference is hard to acurately measure because my digital multimeter can't register the full voltage change in such short bursts. I do have voltage on pins B1 and C16 so I don't think that's the problem.

 

Ok, I have even more info. It appears as though the internal ground switch in the ECM that switches the injector drivers to ground is not working. Am I to presume that I have a bad ECM or is could this be an I-D-10-T error?

 

Start with the basic cheap things unless you have an o-scope . Hot wire the fuel pump on by unhooking the relay and using a paperclip. The pump should prime. Now try restarting the vehicle.
Next check to see that during cranking there is fuel pressure. The injectors will keep injecting fuel no matter what the voltage, although I know there is fuel control code for <4volts, >4 but <9 , and >9. The easiest way to go about fixing a problem like this is to replace parts.

 

Thanks JP. I found out that my problem was due to my 12volt switched power to the injectors and to pin A6 was dropping to 0 volts during cranking. I'm not sure how I ever got it started with that problem but somehow I managed. Anyhow, now that I have that fixed, I can now focus on the tuning.

 

Im having the same problem, I ahve power at on but when i crank she wont turn over, any ideas, in short for somone obviously more noviced then you what does that mean lol hey thanks for the help...-Rav