04 3.9 fuel delivery problem - MustangForums.com

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Old 05-21-2013, 08:08 PM   #1
6667 coupe
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Join Date: May 2013
Location: Missouri
Posts: 2
Default 04 3.9 fuel delivery problem

The wife's '04 3.9 v6 sits inside all winter. Started, ran 3, 4 minutes and died. Changed fuel filter as last year midseason it did the same thing and filter was pretty dirty. Started again and it ran 3, 4 minutes and died again. Now won't hit a lick.

Seven wires disappearing above the fuel tank, two large (brn/pnk and red/blk) and 5 small. Logic says the two large are the motor wires and when the key is on, there is a constant 12.75 volts there. Plugged in, a short whine can be heard for a split second, but the pump moves no fuel. I've disconnected the fuel filter and connected a clear hose on the tank outlet (pump discharge) and placed it in a bucket. Nothing.

This has a pressure transducer in the fuel rail and is equipped with a FPDM (fuel pump driver module) so I'm figuring with the lack of pressure in the fuel rail with the filter is removed is the reason I have a full 12 volts there wanting the pump to run at full speed to build the pressure.

If it weren't such a pain to drop the tank, it'd be down already but I want to make sure the pump is bad and its not something else, because I am just guessing about the wires the 12 volts is on. Anyone shed any light on the subject ??? Apologizing for the extreme length....and thanking you in advance.
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Old 05-22-2013, 06:47 PM   #2
6667 coupe
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Join Date: May 2013
Location: Missouri
Posts: 2

For a follow up...all the assumptions were correct. The two big wires do in fact go to the fuel pump. The rest go somewhere else except for two of the others that go to the sending unit. There is another plug that the four wires come out of, but it is not accessible until the tank is dropped down pretty far. So the combination of wires in the seven wire plug come from either the FPDM or the CCM or a combination of both.

Kinda aggravating to figure out because the Haynes manual I bought specifically for this job DOES NOT include the wiring diagram for the returnless fuel supply with fuel pump driver module and fuel rail transducer.

Long story short, it took three hours by myself to drop the tank, remove the faulty one and install the new O'Reilly supplied replacement. $227.00 for the pump and a trip to the local Ford dealer for a replacement fuel nozzle grommet that must be cut out in order to remove said nozzle without damaging the on board check valve. Little chunk of rubber was pennies over $20.00.

Primed the system with a few key twists and hit the starter and she is purring like a kitten.....an expensive kitten though. Can't imagine the repair cost at the dealership !!!
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