The Stovebolt Site Forums The Shop Area The Electrical Bay 1951 chev truck gas gauge

Can the gas gauge be adjusted to read more accurately? My sending unit is good, resistance is smooth 0 to 30 ohms through the sweep, the gauge itself reads 27 ohms. These are being bench tested, ground to the back of the gauge is good. The gauge reads about 1/4 tank when float is fully down, about 3/4tank when fully up.

Sure sounds like the pivoting arm of the sending unit needs to be tweaked.

Is that gauge reading on the bench or installed in the tank?

Zero ohms = Empty
~ 30 ohms = Full
~13 to 16 ohms = 1/2

The tank level sensor has a metal stop for empty and full.

Remove the gauge wire on the tank. Ground that wire. The gauge must read empty.
If not, do you have a 6 or 12 volt battery and if 12 volt, what voltage dropping device are you using?

Is this an aftermarket gauge sender? I ask because those must be adjusted carefully for the internal height of the tank or the readings will be forever wonky. There are two adjustments: the position of the sender body and the length of the pivoting arm. Ideally, the sender unit must sit so the pivot point is midway between the bottom of the tank and the top...in the AD this is usually 5.5" from the top. Then the length of the float arm is 1.068 times that 5.5" measurement or 5 7/8" from pivot to midpoint of the float. If you have everything set up that way, you'll be good.

If you want a sender that is designed to last and to be accurate, here is the best option I've found: eBay seller's ID is renbusan and the 0 to 30 ohm sender he sells was made in Taiwan and designed by somebody who knew exactly what they were doing. The good points: wiping surface is flat and not arched, contact fingers are metal and won't wear out as fast, resistance compound is poured in place on the outside of those contact fingers so it isn't subject to friction, body is either nylon or hdpe...maybe delrin or something that won't degrade in ethanol fuel and the price is good/free shipping. Here's a link:

https://www.ebay.com/itm/261122347319?hash=item3ccc1ad137:g:FBgAAOSwpPVgBuwZ

Good luck

While we are waiting for the poster to respond, I was thinking that if the signal wire on the tank level sensor, was removed and grounded, the fuel gauge should be showing fully empty. This would help isolate the problem between the gauge and level sensor. From the poster's first comments, the gauge is being bench tested and the gauge reads about 1/4 tank when float is fully down makes me think the problem is with the gauge or something wrong with the supply voltage. I may be wrong. Have to wait and see.