The Stovebolt Site Forums The Shop Area The Electrical Bay Fuel Gage

I have replaced the wire harness,sending unit and gage.
Filled the tank and the needle barly moves anyone have a idea what is wrong? :confused: :confused:

Bad ground, float could have a hole in it or it could be wired incorrectly on the back of the gauge. Some places to start anyway. Good luck.

I have a ground wire from one of the mounting screws of the sending unit to the cab floor,should there be one from the back of the instrument to a ground ?
I hope there is not a hole in the float it is a new part

pull the sending unit and see if it has gas in it.
did you get the correct unit for your voltage system? 6v and 12v need i believe 30 and 60 ohms but don't quote me on this. just know they are different.
check grounds as shipwright says, especially in my 6v system, grounding is 98% of all problems.
the instrument should already been held to the dash with some nuts that provide ground, so i wouldn't think you'd need extra grounding there but it never hurts.

ground the sending wire at the tank,the guage should read full.unground it and the guage should read empty.

Pull the sending unit and see if you move the float the gauge moves with everything grounded. Sometimes the lever on the unit will bind up...

I wouldl first check the sending unit to see if they sold you a 6-volt sending unit which runs on 0-30 ohms or the 12-volt sender that runs on 30-90 ohms. You need the 6 volt one to match your dash gauge. I would bet a policemans donut that you have a 12-volt sender which explains why you have limited readings you are at the top of the 6-volt scale and the bottom of the 12-volt scale...Randy

ok dumb question time here goes.......I have a 12 volt system
How can i tell the difference between a 6/12 volt unit?

Blue - if you got one for yer year, it's 12v - all TF are 12v, gauge and sender - where did you get the replacement gauge, new or used? I'd suspect that, but an ohm meter will check that the sender works

Bill

I purchased the wire harness,new gage and sending unit from chevy duty.
I think the most likly cause is a poor ground somewhere ?

'57, I had a problem with my gas gauge as well. You really need to make sure the place where the gauge contacts the dash is clean in order to ground. Then, temporarily connect a wire from the lead on the gauge that goes to the sending unit and run it directly to the frame somewhere. When this is connected, the gauge should read full. If not, the problem is at this end. If it works, the problem is at the sending unit end or in the wire from sending unit to gauge.

There is one tiny exception to the TF 12v rule - the '55.2 6-cylinder GMCs. A bit of a "gotcha" to keep everyone on their toes.