hello,

I desperately need help, hoping you all can. 2 weeks ago, the car was struggling to start, but ran fine when I got it going. I changed the fuel filter and all seemed well until yesterday. It took forever to get it going, stalled once on the way home, then ran good once I got it back going for 15 min til I was home. now it just will not start. I changed the fpdm with no success. tried finding the fuel pump relay with no success. no fuses are popped. is the relay hidden somewhere funny that I'm not finding? is the pump shot? any thoughts and ideas are appreciated.

 

turn key to run and push in the schrader valve on the fuel rail and see if it is pressurized. if it is, gas will spray out of the valve.
if no pressure in the rail, i would take a guess on a faulty fuel pump.

 

Moved to 5.4L forum.

 

update, replaced fuel pump no success. I don't know wtf is wrong with this thing

 

pump is still not turning on

 

Have you scanned the computer for codes?

 

yes, shows low pressure at the rail. I can't remember what code exactly. I can scan it again this afternoon

 

If the fuel pump circuit in your 2006 is like that on our 2003 5.4L the fuel pump relay is on the bottom of the Central Junction Box (CJB) or commonly called fuse panel. It was moved there with the 2003 model change. The relay in ours is a 20A relay and the pump draws about 15A. The contacts get corroded with use and affects pump motor operation. Even though there may be 12v getting to the inertia switch the current flow thru corroded relay contacts can be reduced. The best way to tell if the pump/relay are working properly is to connect a fuel pressure gauge to the test port on the fuel rail. Harbor Freight's tester ($15) is adequate. The relay can be replaced after removing the fuse panel by someone good at soldering circuit boards. The fuse panel can replaced, but they're usually $300+. I rewired our Excursion (the Expedition is next) to use the factory fuel pump relay output to trigger a new 40A relay. This reduces the current going thru the factory relay contacts from 15A to .2A which should extend the useful life of the relay.