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Discussion Starter #1
2004 6.0 f350. Fuel pump issue. Just replaced the pump in the HFCM last week! Truck ran great up until I filled it up about an hour ago! Don't think my fill up had anything to do with it but I drained the water separator and fuel looked perfect...I'm an aviation mechanic and I'm used to completing fuel samples! When I turn the key on but do not start the engine, my secondary bowl fills up with fuel, I start it and runs fine for about 15-20 seconds than starts to miss, checked the fuel pump and it was not running. Checked the voltage at the wires, 10.7 volts for the first 20 seconds and then it never turns back on...what supply's the power to the fuel pump that is "bypassed" during the initial start up procedure that could cause this issue??? I'm pulling the passenger kick panel off right now to check the inertia switch! Thank you in advance! I live in Kodiak Alaska and there are bears out here! I don't want to get eaten while fixing my 6.0! :)
 

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Welcome to the site! Have you done another fuel sample since you have started having troubles? Do you have a monitor to check for codes?
 

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We don't get the best quality fuel up here in Kodiak, I change the filters about 2-3 times a year and drain my water separator on a weekly bases! I never really get anything out but everyone in a while a bad shipment of fuel arrives and it becomes the talk of the town! I drained my fuel about a week ago now and just after this started happening. Both samples looked fine with no water or particles..aka "clear and bright".
 

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do u have any kind of a monitor to pull codes with?
 

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just fyi the fuel pump comes on with the KOEO for about 20 seconds then shuts off until you crank the motor and it runs

i am guessing you lost a relay or sensor i am wondering if you could feed the pump 12 volts to get it home
 

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the pass panel should have a hole to access the inertia switch
worth a try but it kills power to the pump so you wouldn't have any power to the pump even at key on IMO
 

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Yeah...I can make a jumper to get home...if I can fined some wire! But the KOEO, it runs fine, stops after 20 sec...I start the truck and it never comes back on...is there a pressure switch or something in the secondary bowl/fuel lines that says...hey I need more pressure or does the pump run constantly when the engine is running?
 

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Discussion Starter #8
the pass panel should have a hole to access the inertia switch
worth a try but it kills power to the pump so you wouldn't have any power to the pump even at key on IMO
That's what I was thinking...complete kill switch.
 

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do u have any kind of a monitor to pull codes with?
Yes, my Bully Dog tuner(always on no power when not towing). I had #2 and #4 cylinder contribution /balance then I shut it off before I did any damage. And monitor checks not complete
 

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you could make a jumper from the running lights or trailer harness ( wires close to the pump )
the pump runs it's not controlled so if u can get it on it would likely get you home

but that is a wild guess

that I would totally try
 

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Discussion Starter #11
I have a 10 amp fuse going into a cigarette lighter with about 10ft of wire...almost done building it now...if the fuse doesn't hold, may just go straight to cigarette lighter, I think that has a 15amp fuse anyway!
 

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Discussion Starter #12
I still need to find out why it gets power KOEO but not after start up...right now I just want to get home! :) and thank you to everyone who has helped! Still looking for the real solution! I'll post if she fires up...and makes it home!
 

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i know you need to get it sorted
we are just trying to get you away from the bears LOL


i wish you had a comprehensive code reader i think it would show what is going on

i do not know what sensor the PCM uses to signal the fuel pump to power up after start

did u have rpm ?

it seems like it would use a crank sensor or ?
 

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Discussion Starter #14
Yep...everything worked fine, RPM and all gauges...it just started to starve for fuel...did some trouble shooting and found the fuel pump not working! Started with a small miss, then more and more started to miss...shut it down, filters are about a month old and can't seem to find where the power comes from! I wish i had a schematic on me...looks like I'm chasing wires tonight!
 

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i have the schematic and the ford book is a pain but the fact it powers up makes it look like a pcm command problem to me
 

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trying to find some info
here is some stuff for an 04 some advice doesn't apply but some might help

The fuel pump fuse is #40 in the under dash fuse panel. It is supposed to be rated for 20 amps.

The fuel pump relay is integrated into the under dash fuse panel. It is not serviceable separately from the fuse panel.

As for the inertial fuel shutoff switch, the fact that it's not tripped doesn't mean that it is good. Is it still connected? Is it capable of flowing current to the fuel pump?

Ok, so you've got a P0231 in memory. Does the engine start? If not, is it because the fuel pump isn't operating?

If the fuel pump isn't operating, and the fuse is good, check for the presence of power on the dark green/yellow wire on the inertial fuel shutoff switch connector. There should be power there for 20 seconds after turning on the key. If so, start moving downstream: check the pink/black wire in the same connector. Then check the bank of connectors under the master cylinder to verify they are all secured. Then crawl under the truck and check for power at the fuel pump itself. If you have power all the way to the fuel pump, then check for ground at the fuel pump connector, black wire. No ground? Then keep on going. Ground goes back through that bank of connectors under the master cylinder, into the truck, and to the body near the parking brake pedal. Got power and ground to the pump? Then you've probably got a faulty pump....
 

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Discussion Starter #17
Update: all fuses are good and I'm not throwing any codes. I got to the house and grabbed my big code reader, I just have the contribution/balance codes when it starts to lose fuel. When I prime the fuel system(switch key on/off a few times) then start the motor it runs smooth and perfect! That rules out injectors or HPOP. When I pull the fuel pump fuse in the cab "#40 fuse" the truck shuts off instantly, almost like I turned the key off. Inertia switch works as it should, checked with multimeter. Checked the wire harmed to the HFCM, all wires were fine. I'm not sure where to go next...truck and I are out of harms way but I don't know how to switch this thread over to non 911 emergency so I apologize! PCM is probably next...have it flashed!?! I don't know!
 

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pcm as you look at it

connectors in this order

A C (t in the pdf) B
#5 and #19 in connector b look interesting ?
 
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