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Fuel Pump Module - I can't be the only one

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Old 02-05-2012, 12:04 PM
doughboysigep doughboysigep is offline
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Cool Fuel Pump Module - I can't be the only one

So I have yet one more reason to wonder what the the egineers at Ford are thinking. First it was the whole spark plug debacle. Now it's the "fuel pump module". Story starts a several months back. On a moist day I was headed out and the truck ran very rough, "clunky", like it wasn't getting gas. After 15 miles and a stop truck ran fine. Didn't think much of it and truck ran fine for month or so. I was then away for a couple days and came home to find my truck wouldn't run (started briefly then died). Local mechanic thought it might be a fuel pump issue but then got truck running thinking it might have been a delayed inertia switch in front panel (I had hit a deer a week or 2 prior). Again, not thinking much of it continued to drive truck with no issues for awhile. Then one rainy moring on my way to work the truck was running very rough and "clunky" again. It died several times and finally for good. After getting it towed to the mechanics, he figured the fuel pump was finally shot. The end to my long story is it was the fuel pump module (luckily a lot cheaper fix than the fuel pump) - half of the housing was gone (corroded away) adn moisture was shorting the pump electronics. My b!tch is this: why, if this module is half encased in plastic do the engineers feel the need to encase the other half in metal (appeared to be cast aluminum)??!!????!! Of course it makes sense to have an electrical unit that is mounted underneath the truck where it can collect all the moisture, snow, salt from the road encased in a corrodable metal housing. No no, don't put it all in plastic, just half of the unit. MAKES PERFECT SENSE!! I thought to be and engineer took some sort of brains and common sense. Must be not at Ford. I can't be the only one with this issue and wondering WHY!!! - it must be widespread??
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Old 02-05-2012, 12:18 PM
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tbear853 tbear853 is offline
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Where have you been? Thee are threads here and the "other" websites devoted to these trucks, I and others have posted time and again in them. It's not so widespread that all are adversly affected, but water and salt and snow and ice and other such conditions certainly play into it. As you saw with yours, they will continue to work after they have holes or are broken.

Below is a thread I posted in January 2011, there are others.

Well, we just drove the truck to Conyers, Ga last week and got back home night for last about 12 midnight, came back across the Smokies with a coat of snow .... and yesterday we unpacked and got the mail, washed the truck, etc. 550 miles each way.

Late last night I was browsing the tech articles here as I enjoyed a cup of coffee, and came across a tech thread about a "Fuel Pump Driver Module" located on the back side of a crossmember under the bed.

I read it and one poster posted of his on his 07 being "gone". Today I backed the truck up on my shop apron, dropped the spare, removed the module and found it had some minor corrosion.

I cleaned it off and applied a coat of clear laquer.

I cleaned the frame crossmember area as well, minimal signs of corrosion there.

I applied a couple coats of paint (no picture of it painted, but I did) and let those items dry while I tackled the issue of stand offs.

I took two longer M6 x 1.0 x 40 bolts and chuck them in a vise with aluminum faces and cut the heads off and then filed the ends smooth. Then I installed a Nylock nut on each leaving me about 1/3 of the threads to go into the frame crossmember, the rest above the nut as a stud. I installed these studs and snugged up the nuts against the crossmember.

I applied more clear laquer to the area on the studs and nuts against the crossmember.

I cut two pieces of 5/16 fuel line a little longer than the height of the nuts and slipped over the nuts., then slipped some 1/4" washers in place, set the module in place and saw it had about 3/16" between it's back and the crossmember. I slipped two more 1/4" stailess steel washers over top and another pair of 6mm Nylock nuts which I snugged down.

I thought I was done except for plugging the wire in and putting the spare back.


I went to plug the harness connector C433 back in place on the mudule and I felt something ***** my finger. I felt around the connector and suddenly the light blue wire with red tracer was broken about 3/4" from the connector where it vanished into the plastic loom. I know the wire had to have been partially intact as I drove the truck to the apron, and I never pulled on the connector ..... but the wire broke.

Got my magnifying glass out and some light, the blue/red wire had been chewed through and appearantly a single strand, maybe two ... had held it. The orange wire was chewed too, bare copper showing and several strands damaged. These two wires are 20 gage, very small and go to terminals:
1 (blu/red _ Fuel pump driver module monitor)
6 (org _ Fuel pump driver module control).
They are side by side in center.

First thought .... "Damn".

Bad squirrels.

Then immediately .... Well, this isn't so bad, far better to find now, here, instead of on the interstate at 10PM in holiday traffic 250 miles from home?

Bad squirrels.

Remove some factory tape and open up split loom and free up wires and find some in my wire box close to same color and some shrink tube and splice in pieces for both these wires. Splices prepared, soldered, shrink tube shrunk, wrap with a few rounds of good Super 33 tape, close loom, tape up, hook up again ..... took a few moments to write, a couple hours laying on back reaching and trying not to damage wire in connector end.

Bad squirrels.

Finish taping loom all way to connector and shoot it with fine coat of clear laquer, clean spare up, address air pressure, put in place, start and move truck back to it's carport.

Bad squirrels.

Last year I had to repair the whole harness between the rear tail lights of my '77 same deal. All in all, a productive afternoon doing some preventative maintenance that may save me a bundle compared to what could have happened, and a good lesson as to why the manufaturer goes to such great lengths to secure wire harnesses in place.


I also noticed that the factory method of bolting the module to the round crossmember in a place where it's not as flat as it looks stresses the modules housing, mine wasn't bent or broken ...
... but if one were to overtighten the retaining screws that factory used it would have broken it as the mounting ears were not fully against the crossmember.

And long stories are easier to read and thus more likely to be read by more people if the author just breaks the story up into smaller groups of words .... like paragraphs.
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Old 02-05-2012, 01:18 PM
Lead Head Lead Head is offline
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The fuel pump driver module contains transistors (probably mosfets), that switch on and off at a high frequency to modulate the fuel pump speed. When ever a transistor switches on/off, off/on, it generates quite a bit of heat.

When running, that module probably gets quite hot, and uses the aluminum to dissapate the heat.
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Old 02-05-2012, 01:57 PM
skunkoffroad skunkoffroad is offline
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Originally Posted by Lead Head View Post
The fuel pump driver module contains transistors (probably mosfets), that switch on and off at a high frequency to modulate the fuel pump speed. When ever a transistor switches on/off, off/on, it generates quite a bit of heat.

When running, that module probably gets quite hot, and uses the aluminum to dissapate the heat.
+1 My thoughts exactly
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Old 02-05-2012, 02:17 PM
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I replaced mine last november due to corrosion. I wasn't experiencing any drivability problems yet (luckily). I happened to be under there checking the air in my spare tire and saw a drop of water comming out of a crack that had developed in the case. Ordered a doorman unit from rock auto and installed that. The new ones come with bushings and longer bolts so that the aluminum case does not make contact with the frame.
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