I am brand new to the forums - and we recently became the proud owners of a beautiful 77 F250. I am stoked to have found this community and already found so many useful posts.

I am starting in on a list of things to go through on this truck, and I am now on the *non-functioning fuel gauge*. I have found a handful of helpful threads about the fuel gauge not registering, but I wanted to use this one to go though mine - hoping to get further input if I run into snags, and hoping this thread will contribute to the wealth of helpful information on this forum.

• This truck has two tanks, with a switch on the dash to go between them.
• We filled it up last week when we bought it and it was nearly empty, taking nearly all the 16 and 9 gallons that the main and aux will take.
• Regardless which tank I switch to, gauge still reads empty
• I have tracked down the float unit plug on the main tank (and the wire running off the aux tank - but that plug is harder to get to bc its up under the bed, above the spare)
• I'm getting 80 ohms when I put a meter onto the two posts coming out of the float unit.
• Next I am going to ground the wire that runs to the tank to see if that gauge moves at all.

1977 F250 Fuel System: Float Unit Plug





1977 F250 Fuel System: Float Unit Send





1977 F250 Fuel System: Float Unit Pig Tail

 

Seeing as neither gauge works, I don't think the problem is sender related.
Check both anyway just to eliminate them as a possible problem.
I would suspect the problem is either gauge or possibly the switch itself.
Do the other gauges in the cluster work?
BTW, welcome to the FTE family. There are a lot of good, knowledgeable people here.