Ok, I have done a search in the forums and have found some good info, but not what I need. I have a 93 F150, 5.0, auto, dual tanks. I was driving along and the truck quit running like it was out of fuel. Swapping tank selections didn't work and it was pulled home. After looking on the site the info pointed me to the electrical system. I found that I have power to the main yellow wire going into the fuel pressure relay but none coming out. So I jumped the connections and heard the pumps kick on. Great so I replaced the fuel pressure relay and still had the same problem. When I add power across the relay ever thing seems to work, but still won't fire up. While checking the relay box for loose wires I found that if I used a test light on the green/ yellow wire coming from the fuel relay, the light would light up and the pumps tried to work. While looking at the wiring diagram I see that the ground to the system is located after the fuel pumps. So one pump is louder than the other pump, when I force them to work. Could this whole problem be from a faulty fuel pump. By the way if I add fuel through the TB the truck fires right up.

 

I wouldn't discount a possible electrical problem just yet, the PIP circuit and TFI are notorious. When they cool down, boom they work again...have you pulled any codes? you may want to take a fuel pressure reading as-well, 2 pumps failing is long odds though. In normal start sequence do you hear a pump kick on for a second or two? things to check out also are the selector switch, and the emergency switch

 

DI you replace the old relay with a new relay?

 

Slip Ford Man - I have not pulled any codes and I don't hear the pumps cycling when I first try to start it. I have checked power to the selector switch and the emergency switch, I have power when I use a jumper wire.

Nealcrenshaw - I did replace the relay with a new one.

 

check to see if you have continuity in the inertia switch.

 

fordmudder92 - I have continuity to the inertia switch when I use a jumper wire across the fuel pump relay.

 

Check the Red wire that feeds power to the coil of the Fuel Pump relay. Use this for reference:

Courtesy of FordFuelInjection.com

The ignition key turns on the PCM relay which in turn supplies power to the Fuel Pump relay coil. The PCM also supplies the return path for the Fuel Pump relay coil.

 

mississippi >> If I can help, contact me. I am in Biloxi all the time.

 

Thanks Gator,
But work has me snowed under right now. You know after looking at the wiring and all I think the whole system grounds after the fuel pump and I think that if my if one of my pumps are bad it may not be getting to ground. When I use a test light to ground it tries to pump. Make any sense?

 

Well I know it been a long time but i got it fixed, my issue was the ECM. I took to it to a shop and they found the right side of the ECM was burned up.

 

Glad to hear you found the cause and got it resolved.