my pickup wont run off the fron tank, it will read how much gas is in it, but it wont use the gas from it, is it the switch in the dash or is it somthin else.

thanks

 

What year truck is it? Do you have to manually move a switch located on the floor to the left of the driver seat? maybe it is your fuel tank selector switch. Get out the multimeter and start checking your wires.

 

So when you switch it to the front tank, it won't run at all? Or when you switch it to the front tank, it doesn't use the fuel from the front tank, but will still run?

Some of the older pickups had a manual valve on the floor by the drivers seat to switch the selector valve - and a switch on the dash for changing the guage only. Later in the 70's it was only a dash switch that moved a electric valve - so there was no manual valve on the floor. Which way is yours?

Marty

 

I have the exact same problem in my 78 f250. the gauge works but it won't run while switched. i assumed it was a problem in the line somewhere but i have never taken the time to track it down. i just don't use the front tank after the first time when i ran out of gas on a full tank out on a lonely nebraska highway. not fun

 

The only real way to tell is to have a 5 gallon can of fuel with you.

While you are near home (don't drive too far away )
Run one tank dry and switch to the other tank.
Now Run that one dry.

Put 2 gallons in either (ONE) tank.
Try & start engine.
If the engine starts & continues to run,It shows that the fuel delivery switch works for that tank.Run it until it dies
Place 1/1/2 Gallons in the other tank that was first empty.
Try & start engine > If it runs the switch & valve works for that tank as well.
If it doesn't,you know it isn't working.
You still have 1 1/2 gallons to put in the tank that works to get you home .

 

In my '79 F-350 we had that problem a few years back.. it was the solenoid valve that wasnt working.. so, the mechanism that actually changed the fuel intake from one tank to the other... i dont really know the "technical" name for it.. and honestly, i couldnt tell you where it is.. my brother changed it out...

 

Sounds like the fuel selector valve. Mine is on drivers side insde frame rail. I have a 78 f150/460. I am not sure if this selctor valve is fused but I'm thinking I saw a fuse saying somethig about fuel.

 

yeah its the switch up by the A/C and heater switches, i leave it on the front tank but it burns the fuel from the back, i could care less but the front tank is full of gas and the back one has a little bit of a leak if you fill it over half way up. its happened to me before but it seemed to fix itself for a few months but this time i was on the side of a highway with a full tank of gas and not being able to use it

 

A lot of people are confused by the tanks relation to the switch.

The REAR tank is considered the Main tank, to access this tank the switch should be in the UP position.

The saddle or In the cab fuel tank is considered the Front/Aux tanks and is accessed with the switch in the Down position.

 

On my 79, the selector switch on the dash is just labeled Front and Rear, Front being in the up position. The stenciling appears to be factory. Also, My 78 Supercab is the same way, although cheap labels have put over them.

 

sounds like we may have a mystery. Lets call the scooby-doo detective agency. Is up the front or rear? and is down the front or rear?

 

To get mine to work I changed just the fuel selector valve on the frame rail on mine to get both tanks to work. Check the wire and boot connector first it is in a rough spot for debris rust and dirt on these things.

 

the down position is front tank, i havnt had time to look at it yet but i kinda think its a wire but i guess ill find out tomorrow

 

Alright, my Dad had this same problem several years back on a 77 F150 460 2wd. He ran out of gas, but the front tank was still full. The default position of the selector valve is the rear tank. Meaning if your switch has no power you can switch it all day long and it will not change the selector valve position. He fought and cussed and fought and cussed and finally called me. I went to look at it and discovered the wiring harness had been pulled off the switch just enough to make it not work. Its easy to pull this plug off when removing a radio etc...

 

My 77 has two tanks also. Front and rear. Rear being main. The gauge is only on the main tank which does not create a problem for me. I only keep aroung 5 gal in the front/aux for just incase.
When I hook up the 5th wheel I fill both. I know that I have 18 usable gal. That get me close to 180 miles.At 170 or when I run out I switch to the main tank which has the gauge. Not a problem. I just dont think it is good to run out though.