fuel pump not running

2003 FORD F-250
150,000 MILES • 5.4L • V8 • AUTOMATIC
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PANHEAD58FLH
  • MEMBER
  • 1 POST
Fuel pump will not run. Checked fuse, it is okay. disconnected line to the fuel filter, still no fuel. added a couple gallons to the tank and took a rubber mallet to it, still no run. Checked inertia switch, reset is made, swapped out 303 relay, tried new relay (both spots) under the hood by the power brake assist on the firewall. removed the radio to find only a flasher relay, not the fuel pump relay as instructed by the computer at "O'Reillys", with the key on the fuel gauge works, and cranking the engine over there is oil pressure, relieved pressure on the fuel rail.
Apr 18, 2018 at 3:19 PM
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WRENCHTECH
  • ✓ASE Certified Mechanic
  • 20,761 POSTS
  • ASE Certified Mechanic
You are going to have to test for power and ground arriving at the plug for the pump. It only powers for two seconds when the key is first turned on so you should have a helper.

This is a computer controlled, Pulse Width Modulated variable pressure system so you will likely need a bidirectional scan tool to diagnose this if it is not the pump itself.
Apr 18, 2018 at 5:00 PM
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