jblan

Greetings everyone,

Here is my situation:

Truck (2004 5.4 Lariat) is running fine one evening, wont run the next morning. Truck cranks but does not run.

Did research online and decided to check fuel pump. To my horror I discovered that a wire INSIDE the fuel tank shorted by evidence of a badly burnt cable. I am surprised I didn't go up in flames!

Close up of shorted wire at connection to fuel pump.




Fuel pump assembly with shorted wire.




Anyway, I purchased a brand new fuel pump and installed it. Tried to crank it up once more and no go. Checked the Fuel Pump Driver module, looked great, but I purchases a replacement since I read online that this part often is the source of the problems I have been describing.

Tried to crank it again, NOTHING!

Did a bit more research and I should have checked the fuel inertia switch earlier.... I try to depress the switch, but it will not reset.

I have been digging around several forums and I have not discovered anyone with a similar situation.

My question is as follows: What may be preventing the switch from being reset?

I understand the short at the fuel pump may have caused a fuse or relay to burn out, but I am clueless as what to check for ( owners manual has no references to to inertia switch).

I hope someone out there can provide me with some guidance and perhaps get my truck running again.

I appreciate your time and help!
Cheers!

techrep

iTrader: (1)

you have checked the relay and fuses correct...

Rick's 06

+2 on that. If you shorted a wire in your tank, there's likely a fuse blown somewhere. After you installed the new pump, could you hear it priming when the ignition was turned on?

jblan

Good morning,

Thanks for the replies. I really appreciate it!

techrep: I have checked several fuses that I believe are associated with the fuel system (primarily F34 and that looked fine). I am not sure which other fuse may be associated with it, thats why I was looking for guidance. In regards to the relays, I have read that they are soldered on to the main fuse panel and cannot be swapped out.... how can I tell if it gone bad?

Rick06: I cannot hear the pump prime when the ignition was turned on. To take this step a little further, I disconnected the fuel line before the fuel filter and turned the ignition to see if fuel is moving through the lines, but unfortunately this was uneventful.

jblan

I attempted to bypass the inertia switch by jumping the circuit with a paperclip... this was fruitless.

I also checked the fuses and the relay prongs for evidence of shorting/burning out, but I found nothing out of the ordinary.

Perhaps the culprit is one of the relays soldered onto the main panel?

If you feel I may be overlooking something, or perhaps I should take a second look at a particular fuse, please let me know!

Thanks.

techrep

iTrader: (1)

do you have a multimeter ??

gone postal

Fuses can "look" good....and be crispy critters. same goes for other electrical components.

Paperclips are NOT your friend when dealing with finicky electrical circuits, they're just not precise enough, too easy to slip and accidentally ground out and do other damage.

Multimeter and jumper wires with alligator clips are your friend.

Mod (Ret.)

This type of fault is where the factory wiring manual pays for itself; it provides the test points that can be checked for voltage, starting at the fuse, and working back towards the device it supplies. It provides the locations of all connectors, the pinouts of these connectors, the relay and fuses for that circuit (if applicable).
Try googling for a wiring schematic for your truck year to see if anyone posted it.
Then head over to ebay and buy a used Ford factory wiring book. Worth the 20 bucks or less (used one).

jdinner

There is a plastic panel on the outside of the left frame rail below the drivers seat. Check for corrosion on those connectors.
That truck seems to have two relays; one for the fuel pump and one for the inertia switch.
Without a meter and serious testing you could change every component and still find a broken/corroded wire was your problem.
I'm sorry but I highly doubt there was anything wrong inside your fuel tank. Where was this cable you are talking about?

jblan

techrep: I have borrowed a multimeter. I'll start testing at the IS...

bucko: Thanks, I will look for a wiring diagram.

jdinner: I'll check the cables for corrosion... in regards to the location of the shorted wire... it was INSIDE the fuel tank connecting directly to the fuel pump, it shorted right at the connector. I'll post pictures of said wire later today.