Fuel system

Tiny
SOULSNAKE79
  • MEMBER
  • 2006 FORD EXPEDITION
  • 5.4L
  • V8
  • 4WD
  • AUTOMATIC
  • 164,290 MILES
When I try to start my expedition it will crank but it won't start. I have determined that it is a fuel problem since there isn't any fuel at the rail. I have replaced the fuel filter, fuel pump, fuel pump driver module, crank position sensor, and both cam position sensors. I have also pulled the central junction box and checked the built in fuel pump relay to see if it was bad and it wasn't. What else should I be doing to get fuel to the engine
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Wednesday, March 9th, 2016 AT 7:13 AM

10 Replies

Tiny
WRENCHTECH
  • EXPERT
The first thing you should be doing is using a fuel pressure gauge to know for sure what the pump is or isn't doing.
Check the Inertia switch to see if it has been tripped.
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Wednesday, March 9th, 2016 AT 9:04 AM
Tiny
SOULSNAKE79
  • MEMBER
I checked the inertia switch and it wasn't tripped. I also checked to see if I was getting any voltage to the inertia switch and I am not. As far as the fuel pressure, when I pulled the main fuel line off of the rail and cycled the pump several times, there was not any fuel coming through the a in line. The only reason I pulled the main line is because I can't seem to be able to find the Schrader valve anywhere on the fuel rail.
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Wednesday, March 9th, 2016 AT 12:46 PM
Tiny
WRENCHTECH
  • EXPERT
I don't know how you can know an internal relay is good or not. You're just going to have to track it down with the wiring diagram.

https://www.2carpros.com/images/external/121819835.jpg.gif
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Wednesday, March 9th, 2016 AT 1:06 PM
Tiny
SOULSNAKE79
  • MEMBER
I have the diagrams and I tried bypassing the fuel relay to see if that worked and it didn't. This is what leads me to believe it is something else.
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Wednesday, March 9th, 2016 AT 1:29 PM
Tiny
WRENCHTECH
  • EXPERT
That just makes no sense at all. You say you have no power at the Inertia switch and that comes directly from the relay and you say you jumped that out which would have put power directly to the Inertia switch. You're doing something wrong here. The fuel pump relay is not even accessible.
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Wednesday, March 9th, 2016 AT 1:34 PM
Tiny
SOULSNAKE79
  • MEMBER
This is what I used as a guideline. I understand that the fuel relay is not accessible that is why I tried to jump the wires that come from the relay.
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Wednesday, March 9th, 2016 AT 3:13 PM
Tiny
WRENCHTECH
  • EXPERT
I don't know where you got that diagram but it is different from the one I got from the service manual for that vehicle.

You nee to be very careful what you are jumping there because you can fry your PCM in a heartbeat.
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Wednesday, March 9th, 2016 AT 3:18 PM
Tiny
WRENCHTECH
  • EXPERT
That diagram doesn't even have a FPDM in it.
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Wednesday, March 9th, 2016 AT 3:19 PM
Tiny
SOULSNAKE79
  • MEMBER
Ok so let's say I was stupid and fried my pcm. Then why would my truck run off an external fuel source after I tried all the other stuff.
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Wednesday, March 9th, 2016 AT 8:13 PM
Tiny
WRENCHTECH
  • EXPERT
Nobody said you fried your PCM. You ARE using the wrong wiring diagram and you need to stop trying to jump things in that circuit because you can short out the smart junction box also.
Do this, try applying power to the white wire at the Inertia switch and see if the truck starts.
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Thursday, March 10th, 2016 AT 2:00 AM

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