89 f150 fuel problems

Asked by Kevin Aug 16, 2016 at 04:08 AM about the 1989 Ford F-150 STD Extended Cab 4WD LB

Question type: Maintenance & Repair

I Got a 89 f150 supercab 5.0 with dual tanks, I've replaced
the fuel injectors, wiring, spark plugs, ignition coil, relays
and relay wiring. both fuel tanks and fuel pumps. Yet, my
truck won't start it doesn't have fuel pressure, and I
replaced the fuel pressure sensor. It's not sending anything
from the tanks. Not quite understanding as to why, I even
double checked the fuses. If anyone could help me out with
possible solutions.

me2123 answered 8 years ago

check the switching valve on the frame. I had the mechanical one and had the same problem.

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Eric answered 6 years ago

The fuel tank switch valves are notorious for going bad and causing issues. Are the pumps running? When you turn the key to the run position, can you here a buzzing from the fuel tank for a few seconds? If not check that you have power at the pump. There is 4 wires going to the pump. One should be constant hot, one is ground, one is a fuel gauge input, and the other is a switched hot (acc) wire that should have power when you first turn the key to run and then it should go dead after a few seconds and come on and stay on once the truck starts. Be careful not to cause sparks while working with wiring near the tank.

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