Fuel pump issue
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Staging Lane
Joined: Sep 2016
Posts: 57
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Fuel pump issue Hey Guys, Ive got an LS6 that I stuffed into my wifes 1956 Chevy 210. The motor has a harness from wiring specialties. I didn't run it all through the ignition switch but instead ran the PCM On wire to a toggle switch and then I have a push start button for the starter. When I first wired everything up everything worked great. Then the other day the car started normal and then died after a minute. I noticed immediately the fuel pump wasn't running. I cycled the switch and nothing. Let it sit for about an hr and then went out and she primed the pump and then started but that was it. Once it starts the pump won't kick on and won't prime again until you disconnect the battery and wait a minute. Then the other day it primed and started and idled fine for over an hr. Now today I'm back to the same issue. Is this a bad pump ( Brand new from Tanks Inc. with there tank and also the vet inline fuel filter with regulator). or is it in the ECU?? Any help is appreciated.
Thanks
Thanks
The PCM primes the pump for a few seconds as soon as you turn the key to the RUN position. Then, once primed, it shuts the fuel pump OFF until it sees a signal from the crank position sensor. At this point, I would be tapping into the wire coming out of the PCM that triggers the fuel pump relay. Look here; http://lt1swap.com/99-02_vortec_pcm.htm
Pin 9 on the RED connector is the fuel pump relay trigger wire from the PCM. This is a 12V+ OUT wire when activated by the PCM! Depending on the YEAR of your computer & harness, your wire MAY be the same, or it may not. Please look up your specific wiring diagram. When you find the F/P trigger wire you can simply tie a voltmeter to that wire and watch for the correct signals coming out of the PCM. You will need a helper to turn the key to the START position while you watch the Volt meter to be sure the PCM starts sending the 12V+ as soon as the engine starts turning over. If the trigger wire checks out, you can then test your F/P relay, and then just keep moving down-stream until you find the culprit. Post back and let us know what you find, and what the fix was in case someone else has this problem and searches and finds your post.
Pin 9 on the RED connector is the fuel pump relay trigger wire from the PCM. This is a 12V+ OUT wire when activated by the PCM! Depending on the YEAR of your computer & harness, your wire MAY be the same, or it may not. Please look up your specific wiring diagram. When you find the F/P trigger wire you can simply tie a voltmeter to that wire and watch for the correct signals coming out of the PCM. You will need a helper to turn the key to the START position while you watch the Volt meter to be sure the PCM starts sending the 12V+ as soon as the engine starts turning over. If the trigger wire checks out, you can then test your F/P relay, and then just keep moving down-stream until you find the culprit. Post back and let us know what you find, and what the fix was in case someone else has this problem and searches and finds your post.
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