Many of good and not-so-good mechanics have replaced F-150 fuel pumps only to find out that the pickup still would crank but not start. What these mechanics failed to realize is that Ford fitted the F-150 with a fuel pump shut-off switch, which cuts off all power to the switch in the case of an accident or rollover. This switch has a nasty and annoying habit of losing its retention in the “On” position over time, causing the switch on an older F-150, like the 1991 model year, to activate just from taking a corner and bumping a curb. Resetting the fuel pump switch on the F-150 is a quick task, but Ford hid the button in an inconspicuous location.
Adjust the driver’s seat as far back as it will go. Position yourself under the dash, so you have a clear view of the steering column as it goes through the firewall.
Look to the driver’s side of the steering column and find the black box with a red button on it.
Press this red button until you hear it click and the button remains in the depressed position. This is the “On” position and now allows electricity to flow to the fuel pump.
