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1967 - 1972 F-100 & Larger F-Series Trucks Discuss the Bumpsides Ford Truck

Problem with Fuel Tanks

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Old Dec 15, 2013 | 04:04 PM
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Problem with Fuel Tanks

Hello all,

Having a little trouble with my fuel tanks on a 1970 F-250. The previous owner installed a valve on the drivers side floor board to switch from one tank to the other but it does not seem to be working. How can I test which tank the witch is directed to draw from? The fuel gauge does not work either so that doesn't help.
 
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Old Dec 15, 2013 | 04:30 PM
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If it looks like this then it is a factory selector... It should have a face plate with "main -off - aux" stamped into it.

Post a pic of your selector if different.

 
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Old Dec 15, 2013 | 04:50 PM
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That is it. When I have it on the Main setting, fuel backs up out of the auxiliary tank and the truck does not run. There is also an electric switch inside the cab, under the steering column, that does not seem to do anything.
 
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Old Dec 15, 2013 | 05:02 PM
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you should check for aftermarket tinkering. It may not be hooked up the way it was originally intended to work. I know that there was a switch on the dash that switched from one tanks sending unit to another. It was just for the gauge and not the fuel supply. The switch on the floor is the fuel supply tank selector.
 
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Old Dec 15, 2013 | 07:58 PM
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Gembone is right. The valve should be labeled main off and aux. The switch should also be labeled main and aux and all it does is select which tank the fuel gauge reads.
 
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Old Dec 18, 2013 | 07:25 PM
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Thanks for the feedback so far y'all. Do any of you know what the correct way the selector hookup should look at so that I can compare?
 
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Old Dec 18, 2013 | 07:36 PM
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The center goes to the fuel pump and the others go to each tank, if I remember correctly, I'm old. I'm not at home or I'd look under the truck.
 
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Old Dec 25, 2013 | 04:24 PM
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1967/72: Factory installed 25 gallon auxillary tank mounted on the inside of the left frame rail, the fuel cap is exposed.

1967/69: Fuel cap located above scallop (bumpside) line in front of left rear wheel / 1970/72: Fuel cap located below scallop line in front of left rear wheel.

Inside the bed is a shield that protects fuel filler tube from possible cargo damage.

Manually operated fuel tank selector valve located on floor next to the drivers side of the seat.

Selector switch located on far left side under the dash...only changes the dash fuel gauge from one tank to the other.
 
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Old Dec 25, 2013 | 04:51 PM
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Welcome back Bill.
 
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