Fuel Gauge Trouble

[Flightman91]

For some reason my gas gauge only goes up to half a tank. It acts normal and goes down to E as it would if it went up to F. I have no idea why it would do this. Its the stock gauge and from what I'm told the stock sender unit. Any ideas?

[mrollings53]

Fill the tank with gas, then pop out the instrument cluster. Adjust the IPVR on the back of the cluster until the fuel gauge reads full. Do you have idiot lights or gauges in your cluster? Because if you have gauges your temp and oil pressure gauges should be reading wrong too. Adjusting the IPVR should fix those too.

[colnago]

I have an aftermarket fuel sender unit, so this might not apply. But if the float arm is not bent at the correct angle, it will also cause the fuel gauge to read wrong (because the sender is sending the wrong signal). Pull the unit and check out the resistance at each end of the swing.

http://www.fordification.com/tech/fuel- ... -units.htm

Joseph

[HIO Silver]

I had a 76 dent with nearly the same issue. I bought a new sender while replacing the old one discovered the bad sender's spiral resistance windings were all around the bottom so the gauge stayed at full until the tank was halfway empty... then the needle seemed to drop precipitously during the last 9 gallons.

I think your windings are stretched.

[Calfdemon]

Do what mrollings53 suggested first as that would be the first thing to check before you start messing with the float and sending unit. If it is as simple as an IPVR adjustment with a full tank (which it probably is) then that is all you need to do. If that is the problem and you start adjusting the float first, then you will screw up the system from ever getting a proper read when everything is in correct adjustment.

The IPVR's need adjustment after time in these trucks and more than likely, that is causing your problem.

[bgulseth]

ok I would like more info on this. what years can you make theses adjustments on the back of the cluster where are they do we have a link or website.

[Calfdemon]

It actually is really simple... Fill your gas tank completely full and then remove your instrument cluster. On the back of the instrument cluster will be the IPVR (Instrument Panel Voltage Regulator). You can see a picture of it in the 2nd section titled "The Basics" here: http://www.fordification.com/tech/fuel- ... -units.htm

There are 2 different styles that were used in our era trucks. One (as pictured) is adjusted with needle nose pliers in the little plastic circle. Just turn it until the gas gauge reads full. The other has a small screw and I think you need a very small flathead screwdriver to adjust it, but same basic principle.

Anyway, just turn the adjustment screw until the tank reads completely full. This will increase voltage to all of your panel gauges, but if this is the source of your problem, then your other gauges are reading low too and this will fix all of them.

If you do this and cannot get the gauge to read full, then start looking for other problems.