fuel tank selector

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Jun 5, 2008 | 06:53 PM

northern 7.3

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fuel tank selector

i'm having trouble with my tank selector (i think) i runs fine on front tank, has ever since i got it. as long as i've had my truck when i selected from front to rear, INSTANTLY the truck loses power and smokes white and eventually dies. As soon as i switch back its like nothing was wrong. the tank was replaced by the previous owner i realized when i was first checking into the problem, its brand new. the line is not collapsed or broken, no visible cracks. i think its the selector but they arn't cheap so i want some insight b4 i go spending hundreds of dollars in the wrong place.

Jun 5, 2008 | 08:20 PM

PLC7.3

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From: Manitoba

PM me your email addy and I will forward some info......... sounds like air is entering the system from the fuel tank......... is it above 1/4 tank.

Jun 5, 2008 | 11:24 PM

northern 7.3

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yeah it was just after a fill that it first happened. havn't tried in a while. thanx.

Jun 5, 2008 | 11:36 PM

Dave Sponaugle

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From: Nutter Fort, WV

Even if the fuel line was cut off, it would take a bit for the air to make it to the IP.

Jun 6, 2008 | 02:54 AM

Dodge/Cummins

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From: Sweet Home, OR

Both of my CrewCabs ('90 351/5.8L and '94 IDI Turbo) have a TEENY TINY hesitation right exactly when you switch tanks. It's almost unoticeable but it's there. I know this is different than your problem but it's REALLY wierd! Maybe somehow related?

Jun 6, 2008 | 03:09 AM

northern 7.3

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my theory is that the valve itself is only selecting half way or so and blocking any flow of fuel... much like when you pour a jerry can and plug the air hole the fuel no longer flows nice, it "glugs" I cant just switch the fuel lines on the valve to see if that does it, as it has those fibre lines with the
pre-formed ends....not sure what they're called but one is a 90 deg and the other is straight on the valve. priced one out from ford....over 300 bucks if i remember right...napa and a couple other after market stores couldnt get one like it...they could only get the 80's gas engine style valves..

Jun 7, 2008 | 09:35 AM

Dave Sponaugle

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From: Nutter Fort, WV

Does the fuel gauge show the levels in both tanks?

The fuel gauge connection is the last connection to be made when the selector valva changes tanks.
So if the plunger is traveling far enough to make the gauge connection, the valve is working.