Fuel tank woes

vegas39

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so Friday, I filled both tanks and headed out of town to Laughlin. Saturday, I drove to havasu and then back to Laughlin on Saturday night.
Sunday morning, I got in the truck and realized I still had just above half a tank and had gone almost 300 miles.
I switched to the back tank and it showed bone dry and the truck started to stumble, so I quickly switched back and let it clear up.
So where did that full tank of fuel in the rear go? Obviously it pumped into the front tank but now that it's empty, why is the truck not sucking air?
Could it be drawing from both tanks?
Every truck I've had, has had switching valve issues and I'm half tempted to eliminate one tank.
 

icanfixall

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Kenny you can take the oem tank switching valve apart and clean out whats holding it open to both tanks. you need to drill out the 4 rivets and then use self tapping screws to close it up again. It has been done before. Both tank lines will need to be plugged or clamped off or you will drain the tanks all over your chest. Not a nice feeling either. I use some cheap horrible fright small C clamps place on the lines. Mine are rubber hose at the Carrier lift pump. you probably still have the plastic lines so I can't really tell you how to plug those off.
 

catbird7

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Here's some "pictorial" help. I replaced mine due to similar issues.
 

catbird7

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OOPS! Hit post too quickly.... Here's the pics, old vs new.
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vegas39

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Thanks for the info and pics. I'll probably see if I can just replace the valve.
I'm still curios as to how the truck can run so well if it's indeed pulling from both tanks.
Remember the back tank is bone dry.
Wouldn't it be drawing in air?
 

vegas39

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Does Ford still sell that valve? My next door neighbor is a service writer at a Ford dealer down the street from me. He can can get me a discount on parts.
 

towcat

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Does Ford still sell that valve? My next door neighbor is a service writer at a Ford dealer down the street from me. He can can get me a discount on parts.
you are going to need that discount. they go for $300.
DO NOT crimp off plastic line. they do not uncrimp.
 

icanfixall

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you are going to need that discount. they go for $300.
DO NOT crimp off plastic line. they do not uncrimp.
This is exactly why I mentioned about clamping the lines. These have always been a historically expensive valve. Maybe a trip to a walk in and pick wrecking yard may be the easiest choice. you will still need a way to stop the flow of fuel. No matter how you remove the lines... Fuel probably will end up in your arm pits. Gravity plays it tricks on us when we lay under our rigs. BTW this arm pit full of diesel burns plenty...
 

towcat

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This is exactly why I mentioned about clamping the lines. These have always been a historically expensive valve. Maybe a trip to a walk in and pick wrecking yard may be the easiest choice. you will still need a way to stop the flow of fuel. No matter how you remove the lines... Fuel probably will end up in your arm pits. Gravity plays it tricks on us when we lay under our rigs. BTW this arm pit full of diesel burns plenty...
clamp/crimp......the same. any deformation of the plastic line....bad idea.
 

madpogue

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+1; no fun when that supply line starts dumping on you. And you'd be d@mn lucky if you can wash the diesel smell out of whatever you're wearing at the time. I think I washed my shirt about 6 times before it smelled okay, and I just threw out the undershirt.

It was probably drawing from one tank and returning to the other. Common failure scenario, sometimes fixed by the clean-out mentioned above.
 

towcat

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+1; no fun when that supply line starts dumping on you. And you'd be d@mn lucky if you can wash the diesel smell out of whatever you're wearing at the time. I think I washed my shirt about 6 times before it smelled okay, and I just threw out the undershirt.

It was probably drawing from one tank and returning to the other. Common failure scenario, sometimes fixed by the clean-out mentioned above.
FSV changeouts are best done nekkid and using a creeper. fully clothed and working underhoist means your nuts are going to get wet and it's going to burn :O
 

vegas39

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you are going to need that discount. they go for $300.
DO NOT crimp off plastic line. they do not uncrimp.

10-4 on the plastic line. The rear tank is empty and the front tank is accessible for me to take the line off in just a matter of a couple minutes.
I would imagine I could crimp the hose at the lift pump.

Didn't realize that valve was 300 bucks! I would rather have a factory valve as opposed to retrofitting something else.
 

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