Howdy all, as the title says I'm having some fuel gauge issues in a 94 F150. Truck has dual tanks, 302/e4od, and is a standard cab long bed 4x4.

The issue I'm having is the fuel gauge doesnt read accurately... With the front tank selected the gauge will read about a millimeter over empty when the tank is completely full, after driving approx 50 miles the gauge will read beyond empty and will stay there until tank is topped off again.

When running on the rear tank the gauge will read full when the tank is full, but the gauge seems to drop quicker then it should... as in when the gauge reads 1/2 it usually only takes 5-6 gallons to top it back off (19 gallon tank) and when the gauge reads empty you're still fine for another 100 miles.

The truck has done this the entire time I've owned it, about 5 years now. I've never thought much of it, I just set the trip odometer and alternate between tanks while always keeping one tank full. Easy enough for me, but I might as well be explaining brain surgery while trying to get the Mrs to understand and use that process, and since she'll be driving the thing this winter it'll need an acurate fuel gauge.

So that leads me here. I have no clue where to start on this. Both pumps have a healthy buzz and they switch when the tank selector switch is flipped. I'm assuming both sending units are working since the gauge does atleast something.

 

It sounds like you might have two bad senders, one in each tank.

If unplug the pigtail to the tank the gauge should peg passed full.
If you short the gauge wire to ground the gauge should peg passed empty.
As you change the resistance to ground the gauge should move accordingly.