Having problems with this 88 f150. Truck sat for about 3yrs. Wont start. If you spray gas into the intake it turns over and starts, so we thought the fuel pump froze up. So changed pump blew out the line and changed filter.(duel tanks). Started with the front pump. After checking fond out that i dont have voltage on at the pump. Went ahead and changed fuel pump relay. Just found out that I have 10 volts always at the fuel shut off switch under the dash. On the schematic it looks like I should only have it when the fuel pump relay is energized, and I thought then only for3 sec. then and on again and so on.

 

Your truck has 3 pumps. One in each tank and one on the frame.

 

So more likely your HP pump on the frame. Check fuel pressure at the fuel rail.

 

Yes there is 3 pumps. One in each tank and then a high pressure on the frame. If I followed the schematic correct it looked like the hot wire went from the fuel shut off switch by the brake pedal to the tank selector switch to then tee off and went to the high pressure pump and fuel pump in the tank. I was told that fords have bad grounding problems so I then grounded the orange wire that was the ground on the fuel pump connector to the frame. the truck started making some clicking noises down by the fuse box, coundnt find what was making the noise . Sounds like a relay but couldnt find any relays down there. Also when the key is in the run mode I always have 10 volts on the fuel shut off switch. I tried to trace the wires from the shut off switch to the selector switch it looks like it goes somewhere else all thou the schematic say it goes to selector switch. Need help