Anybody know where to find a fusible link, fuse, or circuit breaker for the high pressure fuel pump on the following vehicle?

1989 F-150
4.9L Straight six.
Two wheel drive.
Dual Gas Tanks.

The (Haynes) repair manual I have suggests that there should be two fuse boxes on this truck. I can find only the one under the steering wheel, and it does not have a fuse for the fuel pump. (And all the fuses in it are good.)

Further, the fuel pump relay tests OK. And I've followed the wiring harness all the way from the fuel pump to the battery, and have found no fusible link anywhere so far.

Anybody know where to look?

RBSjack

 

I looked in my haynes manual, and they don't show the power wiring for the later models(that I can find). In the later model diagrams the fuel pump relay is fed by yellow #37. If you go back to the 1984-1986 diagrams, the yellow #37 has a fusible link right near where it connects to the starter relay terminal.

 

I found the fuse links near the starter relay as you suggested. However, they did not match the color scheme in the Haynes manual, so I have no way of telling which is which. Further, all the links seemed firm to the touch, so I could not determine whether any of them were blown.

Does anyone know whether there IS some sort of fuse for the fuel pump in this model?

I'm wondering about just running my own wire straight from the starter relay to the high pressure fuel pump to test it that way.

(1989 F-150, Straight 6, 4.9L, Dual tanks.)

Jack

 

You can certainly run a wire for a test. But I would not leave it that way. See if you can pierce the insulation of the wires after the fusible links, to see if they have voltage. You can use a stick pin, or maybe your test light or meter lead is sharp enough.

 

I wired the fuel pump directly, and still no ignition. (I cranked it for 20-30 seconds straight, 4 times.) The pump DID get warm, and it passed a continuity test, but when I removed the engine side hose from the pump, it was bone dry.

Do I need to pull the pump and bench test it with some fuel? Or is there a way to prime the fuel line leading to the injectors?

RBSjack