Wiring Help
02-13-2014, 03:10 PM
#1
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Wiring Help I have a PSI conversion harness installed on a LM7 engine that is in a 78TA and the problem Im having is when switch is turned to on position the fuel pump and throttle body cycle on and off in sequence with one another. Looking for suggestions to located the problem.
02-13-2014, 03:49 PM
#2
Cycle on and off as in you tried to start the engine and it won't start or you just did a key on / off?
There are a lot of variables missing, however since you mentioned throttle body cycle I'll assume it's drive by wire. This is normal. The fuel pump will come on for approximately two seconds and the throttle body will open and close once or twice to ensure proper operation. This is part of the pre-start test the PCM goes through.
Now if that happens and the engine won't fire... that is a completely different issue.
There are a lot of variables missing, however since you mentioned throttle body cycle I'll assume it's drive by wire. This is normal. The fuel pump will come on for approximately two seconds and the throttle body will open and close once or twice to ensure proper operation. This is part of the pre-start test the PCM goes through.
Now if that happens and the engine won't fire... that is a completely different issue.
02-13-2014, 06:41 PM
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Thanks for the reply. I figured it out, I had the fuel pump relay and the ignition relay wired to the same power source which was causing the fuel pump relay to kick on and off. I got it started for the first time today. excited to say the least.