I recently bought a 1976 F-150 Ranger. It's a good truck but, I have a question about it. There is a switch by the heater controls that says fuel/auxillary. What is the purpose of this switch? Does the truck have an auxillary fuel tank?

Thanks for your time. I'm sure more questions will pop up from time to time.

 

It should do two things: (1) switch the tank solenoid to pump from either tank, and (2) make the fuel gauge read from the tank you're using. How many fillers on the driver side of the bed? Should be a pretty quick check to see if you actually have one or two tanks.

 

It might have the in cab tank as well 76 should be the last year for that option. And then one all the way in the back.

 

There is only one filler neck on the side. But, I can only get a fuel gauge reading if it's on auxillary. If the switch is on main it reads empty. Is it possible the sending unit is bad, or maybe something else?

jdad49

 

Does your truck have a fuel tank in the cab, behind the seat? If not sounds like someone removed the main and only runs with the auxillary, no tank, no sending unit

 

My 77 has the in-cab tank,, it is the main,, my 73 SCS has two in the bed, and the rear one is the,,, one of them!! I forget,, shoot,, and my 76,, and 79,, well the 79 front tank is out,,heck I am gonna have to look again see which is which,,, but yes your in cab should be the main,, and if it is gone,, it no worky!

 

My '76 has 2 tanks, the main is in cab behind seat and the aux is behind the rear axle. Pickupman, I thought '76 was the last year for in cab tanks, what gives with your '77?

 

I thought 77 was the last year,,, well at least on my side of the hill it was!!

 

It was a mid year change for '77. This was due to government safety regulations banning in-cab tanks.
On trucks with both tanks under the bed, the main tank is the rear, aft axle tank. The auxilliary is the forward tank.