1991 Ford Truck fuel system

1991 FORD TRUCK
191,000 MILES • 6 CYL • 2WD • MANUAL
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BLUECOLLAMAN
  • MEMBER
  • 1 POST
Fuel pump will not shut off when key is turned on. I have replaced both pumps and filter, and relay.
Oct 23, 2009 at 10:10 AM
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JDL
  • ✓ASE Certified Mechanic
  • 16,098 POSTS
  • ASE Certified Mechanic
maybe I don't under stand your post? Which pump doesn't shut off? It does shut off when you turn off the key?


https://images.2carpros.com/forum/automotive_pictures/170934_91_ford_truck_fuel_pump_1.jpg

The lite blue wire with orange stripe is ground for coil side of relay. If that wire is shorted to ground, the pump will run anytime the key is on. That circuit is grounded by the computer, when engine running, may have initial prime at key on, for a few seconds, without rpm signal the pump shouldn't run, except for prime seconds.
Oct 23, 2009 at 11:34 AM
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