No fuel pressure to rails

1989 FORD F-250
135,000 MILES • 7.5L • V8 • 2WD • AUTOMATIC
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MRBIGDOG
  • MEMBER
  • 3 POSTS
Truck has sat for a year or two.
Ran fine when parked.
Has dual fuel tanks.
Not getting pressure to the fuel rails.
I don’t think either tank fuel pump is turning on.
Replaced fuel filter on frame in front of the high pressure pump on frame rail under drivers side cab.
Replaced fuel pump relay.
When I turn the key to run position the relay clicks and the high pressure pump comes on for about three seconds and shuts off.
When I try to start it the high pressure pump comes on again until you stop trying to start it.
I’m lost from here, can anybody help?
Jun 23, 2019 at 4:55 AM
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ASEMASTER6371
  • ✓Experienced Mechanic
  • 52,796 POSTS
Good afternoon,

The first thing I would do is drop and tanks, flush them out of all the old no good fuel and replace the pumps. Fuel that old will not fire and will ruin the pumps.

Did you verify spark?

https://www.2carpros.com/articles/how-to-replace-an-electric-fuel-pump

Roy
Jun 23, 2019 at 5:14 AM
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MRBIGDOG
  • MEMBER
  • 3 POSTS
Good afternoon,

Thanks for the reply.
We pumped most all the gas out of both tanks and replaced with new.
Yes it has spark, if I put a little gas in a spray bottle and squirt it into the plenum it will purr like a kitten until I stop.
Jun 23, 2019 at 9:28 AM
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ASEMASTER6371
  • ✓Experienced Mechanic
  • 52,796 POSTS
Do you hear the pump run with the key on?

Roy
Jun 23, 2019 at 10:04 AM
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MRBIGDOG
  • MEMBER
  • 3 POSTS
I cannot hear either tank pump run with the key on no matter what position the fuel tank selector switch is in.
Jun 23, 2019 at 1:12 PM
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ASEMASTER6371
  • ✓Experienced Mechanic
  • 52,796 POSTS
Okay, I attached a couple of diagrams for you to view for the circuit for the pumps. You will need to test for power to the pumps to verify the wiring is good.

https://www.2carpros.com/articles/how-to-check-wiring

Roy
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Jun 23, 2019 at 7:32 PM
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