The Stovebolt Site Forums The Shop Area The Electrical Bay Gas Gauge ON FULL

I wanted to see if anyone would help me with my gas gauge. Since I've owned this 1950 Chevy truck (3100) It has always read empty on the gas gauge. I found the float had a crack in it. So I replace it with a new one. I also rewired the truck (American Autowire). I installed a 12 to 6 volt reducer on the gauge. It reads full in the tank even though it has no fuel. What do I do?

Open circuit between the sending unit and the gauge. When the sending unit is in the full position there is maximum resistance (no current flow) to the gauge. An open circuit (no current flow) is telling the gauge the tank is full no matter the amount of fuel in the tank.

Tiny can elaborate on this, but you need to match the OHMs on the sender to gauge. I had a 90 OHM gauge, and a 120 OHM sender. it read full all the time. Even when I stalled out in one of the busiest intersections in town from being out of gas.

i just put a 270 in my 40. i didnt touch the electrical system. when i turned on the key the fuel gage was past the full mark. i know it wasnt right because there was only two gallons of gas in the tank. i checked the resistance on the sender to ground and i got nothing. wtf i didnt do anything to lose it. checked from sender wire to fuel valve at the tank and got 2 ohms. i dumped five gallons of gas in and i got 8 ohms but only when i had the sender wire via a jumper to the tank shut off valve. i lost my ground, how did this happen. when i put the engine in i ran a new fuel line from the tank and the fuel pump and add a plastic filter close to the shut off valve. the rubber fuel lines are what broke the circuit. after i ran a seperate wire from the sender housing and grounded to frame the gage read 1/4 tank.
before that the fuel line was the ground.

maybe when you replaced the float you lost your ground.

gmindel,
the gas gauge should read full when powered up and there is no connection to the sender post. It should read empty when you ground the sender post and it is powered up. You should try these two tests at the sender end and if it fails, try it at the gauge end.

Okay.... I'm still not getting it... I took the wire off the sending unit.... the gauge still read full... I grounded the wire.... the gauge still read full... When I shut the power off, the gauge goes to empty.... What next....

do a continuity check on the wire between the gauge and the sender, may be open somewhere along the way - if it checks good, likely the gauge is bad - as a double check you can put a temporary wire or jumper from the gauge terminal that goes to the sender right to ground nearby and see if it acts the same

Bill

Take the wire off at the gauge. if it stays on full with no sending unit wire attached the gauge itself is grounded out at the post that goes to the sender. What condition is the cardboard insulator in? You may have to get something to replace the insulator with. A carving out of a milk jug should do the trick.

I did the test on the sending unit and discovered it to be bad. I just ordered a new one from LMC.

Sending unit it, rewired and all working great. Thanks to everyone... I'm a pastor, so going to the Stovebolt website for help is like going to the bible... I get just what I need.