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Today is the first day I filled it all the way up. I was down below a quarter tank and thought it was time.... $30 later and only 13 gallons I realize we have yet another mystery to solve....
Tank is full but the gauge reads not. Either this 18+ gallon tank only holds 13 gallons or I missed something in the fine print.... Lol. Where should I start here? I don't really have much experience with gauges like these. Should I Pull the bezel and check the connections or assume somethings wrong behind the seat? Thanks in advance.
With the ignition on, ground the sender wire and the gauge should peg.
If it does, the the resistor windings on the sender have slipped down.... like long tube socks going down to your ankles. Not a big deal.... your gauge will read slow or fast depending how the windings have bunched down. Your odometer works, right? Just keep track of how many miles have been driven and fill up again in 150 miles to "gauge" your gauge. Make notes!
You already know that a quarter tank indicated equals about six gallons.
Yup, your sending unit is awry. There are like 4-5 screws that hold it into the tank. You can test it like HIO mentions to see if the gauge itself is okay.
If you want to fix the sending unit, just slip it out of the tank(doesn't matter how much gas is in it) and you can easily see if there is a problem with the arm/float.
This is the in cab gas tank sending unit. Where the float arm attaches to the sending unit there is a point contact arm that touches a series of windings. If the point contact isn't climbing to the top or dropping to the bottom of the windings it will not read full or enmpty. If you remove the sending unit from the tank you can actuate the arm by hand and see if the gauge goes from empty to full. If it does then bending the float arm will correct this problem. You will have to ground the unit with a jumper wire so that it works. Personally I would rather have a tank with gas in it when it reads empty than run out of gas when when I think theres still some in it.
With the ignition on, ground the sender wire and the gauge should peg.
If it does, the the resistor windings on the sender have slipped down.... like long tube socks going down to your ankles. Not a big deal.... your gauge will read slow or fast depending how the windings have bunched down. Your odometer works, right? Just keep track of how many miles have been driven and fill up again in 150 miles to "gauge" your gauge. Make notes!
You already know that a quarter tank indicated equals about six gallons.
Odometer works just fine. I'm gonna pull that sender out this weekend and have a peak
Good chance the fuel sender could be bad or a bad ground. However, there's also the chance that the fuel sender is working correctly and that your ICVR (Instrument Cluster Voltage Regulator) could be off and making the gas gauge read low. It's just a bi-metallic mechanical reed switch that can become inaccurate in regulating the instrument cluster voltage over time and with age.
With a known full tank of gas, you can pull the instrument cluster out of the dash to get to the ICVR on the back of the cluster and turn the adjustment screw on the ICVR until the gas gauge needle moves just slightly past the Full mark.
The ICVR will look like this. The adjustment screw is inside the round, plastic circle. Turning the screw CW increases the voltage output. Turning the screw CCW decreases the voltage output.
If you want to move up to a modern IC chip gauge cluster voltage regulator, you can build one for only a few dollars or, you can buy them already made (more expensive) from various vendors (vintage Mustang suppliers sell them).
With the ignition on, ground the sender wire and the gauge should peg.
If it does, the the resistor windings on the sender have slipped down.... like long tube socks going down to your ankles. Not a big deal.... your gauge will read slow or fast depending how the windings have bunched down. Your odometer works, right? Just keep track of how many miles have been driven and fill up again in 150 miles to "gauge" your gauge. Make notes!
You already know that a quarter tank indicated equals about six gallons.
09-07-2016, 11:50 PM
