I just recently installed a new pc m in a 1997 GMC Savana 1500 with a 5.7 it started and ran but it didn't run any good they said I needed a knock sensor so I put in a new knock sensor and she ran beautifully then I shut it off stop 3 hours later when to start back up then the fuel pump is not working or coming on does anyone have any suggestions I've checked and replaced every fuse relays and I am stopped please help
First make sure this isn't an issue with your PassLock anti-theft system. It will shutdown the fuel pump. Make sure the light isn't blinking.
Then, check the ECM-B fuse again in your engine compartment fuse box. Use a test light to make sure there's power on both legs of the fuse.
I tried all that and did the procedure for passlock many times just the fuel pump relay it has constant power but not the power from key power supply jumped the pump it works fine
THe key doesn't supply power to the Fuel Pump Relay's coil to energize the relay
.
That comes from Pin #1 of the PCM's C4 (Grey) connector
.
Maybe "back pin" that pin socket and see if the PCM is sending the 12 volts to the "Control side" of the Fuel Pump Relay to energize its coil and close the "Load side" contacts
.
.
.
Click To Enlarge
.
.