Having a big problem with this expedition. 06 expedition 4x4...wasnt starting and couldnt hear the fuel pump coming on so we started with the fuel pump module. That didnt fix the issue. Moved on and replaced the pump and fuel filter and truck turned right on. Let it run for awhile and shut off on its own about 15 mins later. When i tried turning it on again it was back to doing the same thing as before...just cranking and no noise coming from the fuel pump.

Check engine light came on and got code p0191. This guys got an 04 f150 with the same engine so we were able to swap out fpdm's and fuel pressure sensors. The 04 has no problems and will start with either fuel pressure sensor and with either of the fpdms. I started checking voltage at the fpdm plug right after this. With the key on i do get battery voltage at the white wire and i get a good ground on the black wire.

I tried jumping the pump with some pins at the fpdm connector and the pump came on for split second and then i lost the 12 volts at the white wire. As soon as i take the jumper pin out i get 12 volts again. I also jumped the pump with an outside source (12 volt battery) pump kicks on and i can go ahead and start it and it will stay on. Once i try to jump it using its own 12 volt power though it wont run.

I jumped just the ground pin that comes off the frame to the pump ground and it works 100% of the time...the actual positive wire is the one that gets lost once i jump it. The white wire has 12 volts and as soon as i jump it to the red wire it loses it. Goes right down to zero. Is there something casuing this loss in voltage? Relay? Shutoff switch? Im am completely lost. Checked fuses and those are good. I also have a scanner and as im checking it the truck will sometimes start out of the blue on its own but will only build up to 10-12 psi and then slowly lose it and shut off...then it will go down to zero. On a regular basis it will stay around .48 psi and sometimes go up to 3-4 psi and turn on. But will only run for about 10 seconds and the 10-12 psi...

 

I think there is a fix I read about before. Don't quote me...a fuel pump relay is mounted to a dissimilar metal which causes corrosion and causes the fuel delivery from fuel pump to be spotty at best. Mounted underneath vehicle, passenger side, at rear of vehicle. Try searching on "06 Fuel Pump Issue Fixed" or similar. Good luck.

 

Search this "2006 Expedition FPDM / Fuel Pump issue FIXED - pics"

 

Thats the first thing we tried. We bought a new one and tried it but it was a no go. We took the old one off the expedition and put it on the f150 and the f150 runs perfectly fine with the new one, the one from the expedition, and its own fpdm.

 

Searched around online and found some more info and wiring diagrams along with some pictures.

Went ahead and checked the voltage and ground coming out of the fuel pump relay in the fuse panel. I am getting voltage and ground at the fuse panel connectors amd also getting voltage going to the inertia switch. Also getting voltage coming out of the inertia switch to the white wire at the fuel pump module. Still having the problem where i lose voltage at the fpdm once its connected or jumped....but i still have the 12 v on the inertia switch end.

Now im thinking its either the harness connector or the wiring....

 

You should have checked it with the voltmeter before just throwing parts at it. Sounds like you have a short/open somewhere in the circuit. Trace the wires and see if you can see any that are broken, frayed or blown out.

 

Your volt meter is probably lying to you. A high impedance DVM does not load the circuit enough to get a true reading, it is displaying a phantom voltage on an open circuit.

An analog meter or a simple test light with an incandescent bulb works best in this scenario.

 

Unless you happen to have a Fluke Dual Impedance DMM:

Dual impedance digital multimeters - What's the point?