Testing gas gauge

[madbrad]

I just put in my new auto meter gas gauge and when i turn the ignition on it barley moves. I put 10 gallons of gas so it should move more than that. Im thinking it might be the sender ans i bought a digital voltmeter to read the omh's but not sure how to do it, or what it sould read. Any other ideas on things to check? I dont know if the gauge work before i install the new gauges since the car was just a rolling chassie when i got it.
Thanks

 

[Bullitt]

summit lists the resistance reading for the various autometer gauges. you have a "ford" style, so just look up your gauge in summit.

as far as measuring resistance. put your voltmeter on 0-200 ohms and bridge between the sending unit and a spot on the frame. that should give you the gauge reading (if i remember correctly). it's either that or you disconnect the sending gauge wire and run the voltmeter in series...

been a long time since i did it so i can't remember.

 

[ForceFed70]

A quick test to do would be to disconnect the wire from the sender. The guage should stay on empty.

Then take the wire and ground it to the frame. The guage should read full.

Won't tell you if it's the right guage for that sender, but it will tell you if the wiring is good.

 

[steel1212]

Also, I think they suggest that you ground it to the tank. Mine will read full for a little while but as I use up fuel it quickly goes to 1/4 tank. I'm going to run a wire back to the tank and see if that helps any.

 

[stangman16]

Also, I think they suggest that you ground it to the tank. Mine will read full for a little while but as I use up fuel it quickly goes to 1/4 tank. I'm going to run a wire back to the tank and see if that helps any.

Wow, that can explain why mine has a 'mind of it's own'... lemme know if that solves it for you. very interesting.

 

[pabear89]

Also, I think they suggest that you ground it to the tank. Mine will read full for a little while but as I use up fuel it quickly goes to 1/4 tank. I'm going to run a wire back to the tank and see if that helps any.

Replace the sending unit.
the windings are failing on it.

Same as if it only goes partually up, when the guage reads half and your tank is full.


PB

 

[steel1212]

Mine is a brand new sending unit, doesn't mean its not bad though. I grounded my gauge to the top of the tank today...still same thing just goes to 1/4 tank. I may have to invest in a new sender. I'm probably going to check the ohms tomorrow just to make sure.

 

[Capt Dan]

Mine is a brand new sending unit, doesn't mean its not bad though. I grounded my gauge to the top of the tank today...still same thing just goes to 1/4 tank. I may have to invest in a new sender. I'm probably going to check the ohms tomorrow just to make sure.

Grounding it should make it go to full. I think that rules out the sender. Must be the guage or the wire. Try grounding it to the frame. Maybe you have a bad ground between the tank and the frame.

 

[steel1212]

It was grounded to the frame before I moved it. The gauge will go to full when the tank is full but quickly goes to 1/4 tank as the fuel is used.