hard to start

1992 FORD F-150
179,000 MILES • 4.9L • 6 CYL • 2WD • MANUAL
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BLACK60CHURCH
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truck is hard to start and fuel pump runs all the time with key on and engine not running and missing bad in high gear like starving for gas clears up when you down shift, but sometimes real hard to start. has 50 lb pressure. New plugs, wires, distributor, relay for fuel pump, new box on side. When you turn key on with engine not running fuel pump runs all the time, it should kick off after about thirty seconds.

I have put ever thing I can think of the 1992 model do not plug into the new scans cannot find any one with the old type.

Please Help.
Jun 11, 2017 at 5:11 PM
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STRAILER
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Hello,

Does this truck have dual tanks? If so they had a big problem with the fuel switching valve which controls the fuel pump and causes the engine to starve for fuel even with the correct amount of pressure.

Here is a fuel pump wiring diagram (below) and a guide so you can test which is going on either the relay is having a problem or the computer is not signalling the relay correctly.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Please run some tests and get back to us so we can continue helping you.

Cheers, Ken
Jun 12, 2017 at 5:00 PM
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HMAC300
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If you have a dual tank system I have information on how to test it.
Jun 12, 2017 at 5:55 PM
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BLACK60CHURCH
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it has dual tanks and they work thanks.
Jun 13, 2017 at 8:20 AM
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HMAC300
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here is info n how to test dual tank system. see pic
Jun 15, 2017 at 1:07 PM
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BLACK60CHURCH
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checked compression had 40 lbs on one cylinder the problem burnt valve
Jun 16, 2017 at 7:25 AM
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HMAC300
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that will do it
Jun 16, 2017 at 9:28 AM