Strange Fuel tank problem

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May 1, 2010 | 10:31 AM

seismicdrift

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Strange Fuel tank problem

Hey Guys,

This is a real head scratcher for me. Just bought this 85 F250 6.9L. Went to fill the tanks because both were real low. The front took 11 gal. the rear took 5? So the guages go all the way up and when they run all the way down same thing. The really interesting part about it is that when the guages get below 1/2-3/4 tank it starts cutting out and losing power when over 1700 rpm. Obviously there is something wrong with the fuel tanks/lift pumps/guage floats? Just not sure where to start. Any thoughts from the more experienced crowd? Thanks!

May 1, 2010 | 10:56 AM

Festus Hagen

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From: Maine (NorCal Native)

Time to either drop the tanks or lift the bed, sounds like pickup tubes and sending units.

At the fuel filter, pull the schrader valve out of the bleeder (looks like a tire stem).
Test the flow there, you should get 1/3 pint in 10 seconds of cranking, it should be a fairly air free stream, if you get lots of bubbles it's sucking air, there are several places it can suck air.

Pickup tubes.
Fittings on Tank top.
Tank Switching Valve & Fittings.
The flex line from chassis to lift pump.
Lift pump.
And last, likely least, the main lines themselves.

(Did I miss any places???)

Test both tanks empty as well as full.

-Enjoy
fh : )_~

May 1, 2010 | 11:08 AM

seismicdrift

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I'll check that out

Thanks a bunch I will perform that test this week. any thoughts on the diminished capacity of the tanks themselves? or maybe just bad floats in the tanks? Thanks again.

May 1, 2010 | 11:14 AM

Festus Hagen

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From: Maine (NorCal Native)

I'd say a combination of Sending units (floats) and pickup tubes.

-Enjoy
fh : )_~

May 1, 2010 | 11:31 AM

greywynd

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From: Peterborough, Ontario

When Festus says pickup tubes, what tends to happen is the plastic on the end breaks off, making your last 1/4 tank unusable. Most people take a piece of rubber fuel line, hose clamp it to the end of the tube. Cut a 'V' in the end of the rubber so it can't suck itself flat against the bottom or side of the tank and you're good to go.

May 2, 2010 | 12:11 PM

seismicdrift

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Again, I really appreciate the input guys. I will let you all know how it comes out.

Have Ford will tow, haul, pull or push what you got!

May 2, 2010 | 12:20 PM

oreocreaming

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Joined: Jan 2010

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From: Elk City, OK

i had the same issue on both my tanks. it was the pickup tube screen. the plastic just crumbled and left me with open tubes sitting half way up the tank. ford doesnt offer them anymore, but i found some off a newer superduty. same for the front and rear. dont have the part number anymore, but it did the trick. i pulled off the bed ***go that rout, 6 bolts vs a broken back**** half full diesel tanks are heavy lol. and why mess with both tanks when you can just lift the bed quickly and fix both thanks, then bolt it back down?