fuel gauge reads half when tank is full

[Sam I Am]

When I fill the (only) in-cab fuel tank, my dash gauge reads half.
The gauge reading will then drop at a normal pace as I drive out the fuel, and I estimate that when the gauge reads Empty the tank is still actually half full.
What is the cause of this?

[Thunderfoot]

Could be a couple of different things... Follow this for info on how to find/fix the problem. http://www.fordification.com/fuel-sending-units.htm

[Sam I Am]

Thanks for the link, I guess I just need to look around the site a little more. Lots of good stuff here.

It's a bad sending unit.
It tested 49 ohms full and 97 empty.

But the good news is that the gauge and wiring is still good.

[Thunderfoot]

I find new stuff here all the time, if I could just remember it all and where it was at would be even better.

[rjewkes]

Yup i have a simulair problem mean reads 3/4 when full i checked the sending unit and it will go full scale but i think i have one from a different tank as it will read all the way full outside of the tank and the float end moved all the up. but once in the tank reads this way, never checked the ohms just figured the tank it came out of must have been shorter so it reads emptier?

[fordman]

you might need to adjust your ipvr. on the backof your cluster to make that one read right.

[Sam I Am]

I asked at a salvage yard just down the road and they want $60 for a used fuel sensor.
And that was if I pull it myself.
I don't want to know what they want to pull it for me.
I told them no thanks, and just as I was pushing the door to leave, she asked me, "Don't you want to go out and look?"
I just smiled and told her not at that price, since I can get a new one for $50.

Times are tough, but that is ridiculous to charge $10 over the price of a new part for a used part I removed myself.
I know of a couple of other yards I can check, but I won't pay more than $20 for a used one.

In case I don't find a used one that's usable, has anyone gotten one from LMC? And if so, did it work okay?

[fordman]

i have used ones. but after shipping it might be about 30.00 or a little more (32.00). i dont know about lmc stuff. im sorry.

[njs]

Possibly a small leak in the float causing it to sink lower than it should?
Mine was totally full and lay on the bottom, new float fixed it.

[george worley]

Mine was full of gas to,it had a small slit in it, I dryed it out and soldered it. I Didn't put enough solder on it to make it to heavy. It been alright for over a year.

[fordman]

ford still used those brass floats until 1986 in the trucks. someone said they still had them in stock at ford.

[Fordnatic]

Mine had a red rag hanging over the float arm-along with a couple straws, rocks, change etc in the tank. I guess it's too tempting for the kids with the cap at their eye level. I put a locking gas cap on the day I cleaned it out!!