This is an oldy but still a good fix to remember. SureTrack community member MobleMech had a 1993 Chevrolet pickup in the shop where the fuel pump would keep running after turning off the key. They posed the question to the community, and with the help of fellow community members juniur, Ericsautomotive and others, they were able to resolve the issue quickly.
The following Community Fix summarizes the interaction between members of the community that led to the solution.
Vehicle
1993 Chevrolet Pickup C1500 5.7L
Title
Fuel pump runs with key off, replaced oil pressure switch.
Complaint
Customer complains that fuel pump keeps running after key is turned off.
Diagnostic Steps Performed/Parts Replaced
Checked fuse and relay and they are good. Dropped fuel tank and inspected wires and wiring harness and found no obvious faults. Replaced fuel pump and that did not fix issue. Fuel pump is still continuously running and now truck is, reportedly, not getting any fuel.
Best Answer from Community Members juniur and Ericsautomotive
On some of the older GM trucks, the oil pressure switch would energize the fuel pump. I’ve seen this several times.
Cause
Bad oil pressure switch causing the fuel pump to continue to run when key is off.
Correction
Replaced oil pressure switch and fuel pump stops when key is turned off.