Im bringing my 1986 F250 7.5l back to life, and have it down to the motor will turn over, will try to start if you pour fuel in the carb, but no fuel flows. the Fuel guage is dead, and switching the tanks does not work. But before I begin pulling the dash apart, where is a good logical place to begin looking for the disconnect. I have heard a lot on this sight and others about the fuel pump relay (cant find it under the dash), and also the possibility of a bad oil pressure shut off switch( found, but how to test?). So, any ideas where to begin following?

 

Do you get fuel while cranking the engine over?
This should always be the case since the interlocks are bypassed.

If not, then don't worry about the inertia switch, oil pressure cutoff and fuel pump relay for now.
The pump relay is under the hood on the drivers side.

Check the fuses.

From the sound of it, the switch valve on the drivers side frame rail is not connected or has failed completely.
Even if the switching relay had failed the truck should default to the rear tank.

 

I would find that odd wire on your starter solenoid(I think it's blue? It's on the "I" terminal) and hot wire that and see if you can hear the pump run and if you get any fuel.

 

Thank you for the clear answer, im really not the greatest when it comes to electricity but I do have help here. I already checked the fueses and the fuse block and they are good, so next ill slide under and check that switch valve

 

sorry, and there is no fuel while the motor is turning over.

 

It is a blue gray fusible link that should be connected to the 'I' terminal, if he has one on a late model solenoid.

This is the safety override to power the pumps while cranking.

 

See if you can find two relays mounted together near the drivers side hood hinge.


BTW welcome to the forum.

 

the only relay we could find in that location is for the trailer brake system. Right now im following the power from the battery, working my way back to the fuel tanks. so far, power flows throughout the eng compartment, and now were back to the firewall. Power so far.

 

It may be easier to work your way from the fuel tank forward. Here's a schematic.

 

A troublesome turd since day one!

E5TZ-9189-B .. Fuel Tank Selector Valve-6 ports / Marked: E57B-9F271-BA or E67A-9F271-AA / Available from Ford.

See parts catalog pic below for the turd's applications (F150/350; R = Ranger; E = Econoline).