The Stovebolt Site Forums The Shop Area The Electrical Bay Another Fuel Gauge Problem

I have a 53 GMC half ton. The fuel gauge kind of worked before but it only went down to between 1/4 and 1/2 but the tank was enpty. Purchase a new gauge and sending unit. Now the gauge only read 1/2 when the tank is full. Any suggestions...I don't get it !!

Sift through the many posts on this problem in the forums. Not much can happen to these critters that hasn't been discussed. Now, did you by a matched pair of sender/gauge, ie 0-30 ohms, 90- 0 ohms? If you did, can you bench test it before installation? All you need is a battery charger and a few pieces of wire to make the connections. If it doesn't work on the bench, it's not going to work on the truck. Let us know and we'll move on.

Thanks for the reply...
I don't know if they are a matched pair, I bought them from the same place but didn't ask when I placed the order.How can I tell now ? I will have a look around the forums and see what I can find. I guess I better go on the hunt for a new multi-meter as well. The one I have is old and not very acurate

I love my old analog 260. These new ones (DVM) that jump around while your scratching the lead for a good ground cause me grief. Moving on, hook your battery/charger, gauge, and sender up as it would be in the truck. It goes like this...jumper from battery or charger red (+) to gauge (+) terminal, jumper from gauge sender terminal to sender center terminal (the one thats insulated from mounting plate, jumper from sender mounting plate (thats your ground when mounted) to neg. (-) side of battery. One more jumper from the neg. of battery to case of gauge, if you have a ground lug on gauge, hook a jumper from it to the gauge case also. This powers up the whole thing. You now can move the sender float from stop to stop (top to bottom) slowly and the gauge needle will move from empty to full. If you get any other reading, we will have to dig deeper. BTW, do all this on an insulated surface like wood or shop towel. Now a little advice...if you don't have any jumpers go to your local electronics part store and buy a handful of alligator clips (Muller makes the good ones). Using different color scrap wire, make up a few of different lengths. Also while your at the store, buy a 0-100ohm or 0-250ohm 2 watt variable resistor. Cost of couple of bucks. Down the road these item will be more helpful than a gun in a knife fight.

Okay...thanks for the help. I did as you mentioned and found that both the gauge and the sending unit work correctly. When the sending unit was in the tank and was full of gas it only read half full. The ohms reading on the sending unit was only 17 when in the tank but would go to 31 when I had it out and moved to the full position.When looking at the float position when out of the tank and reading 31 ohms, the float was actually going above the point where it fastens to the tank so it would never read full.I adjusted the float leven to be below the top of the unit and was reading 31 ohms. Put it all back together and it reads full now. Only thing unsure of is if the empty position will be true.I'll test that out as I get lower on fuel, I'll just carry a can of gas as I get lower ... just in case.