Fuel pump wont shut off


#1

I have a 1994 Buick regal with the 3800 series one motor…Sometimes when I shut the car off I can hear the fuel pump running anywhere from 2 to 15 seconds…sometimes it shuts off then starts up again briefly when the car is off…



when the car is cold and I turn the key the fuel pump sometimes keeps running until I turn the key off then turn it on again and I dont hear it running but I can still start the car…



As I said this only happens sometimes…

I have replaced the fuel pump relay 3 times with a junkyard relay and once with a brand new one and I am still getting the same problem…what else could be causing this.


#2

According to the schematic a dark green/white wire from the ECM to the fuel pump relay provides power to trigger the relay.

Since it’s unlikely you have had this many sticking relays, you should take a test light or VOM and check if that wire has 12 volts when the key is in the OFF position.

If so, then the ECM may be defective or there is another external wiring problem that is causing the ECM to continue to provide voltage when the key is off.
Other than that, I don’t see anything in the fuel pump wiring circuit that would cause this.