The Stovebolt Site Forums The Shop Area General Truck Talk Gas sending unit woes

I am not getting a reading on the gas gauge. I know this is a common problem but I was unable to find my answer on Search. I have a 53 6v all new wiring, grounded, and at least 3/4 tank of fresh gas. I once read that the unit could be placed in the tank where the float is hanging up against the side but I have not investigated that yet. What are some other reasons and corrections do I need to know before I start on this project?

Which side of the gauge gets the hot lead from the ignition?
The other side of the gauge goes to the sender.

How/where do you have the system grounded?

Assuming the gauge is connected correctly, disconnected the wire that goes to the sender. Momentarily ground that wire to the frame (with the key on). The gauge should peg full. If it doesn't peg full than the problem is not the sender.

If the gauge has power to it and the wires aren't reversed than the gauge is the problem.

My problem is a little different. I purchased a new 12v gauge and sending unit. Tested it before installation in the tank and the gauge worked perfectly. Once installed in the truck it will only show 2/3 full when completely full. Empty seems to work fine. I confirmed this one time when it showed just past the empty mark and I ran out of gas.

It seems like I should be able to bend the float arm down slightly to get a more accurate full reading but that would probably be trial and error for the correct amount of bending. More importantly, I don't want to mess up the accurate empty reading. Anyone else dealt with this and solved it adequately?

Chuck, I had a similar issue with a new sending unit on my '57. Full only showed about 3/4. I never tested empty by running out of gas, so perhaps my issue was different.

The solution for me was to do exactly as you suggest...bending the float arm down. A full tank was not allowing it to reach its full swing. I did it in small increments and tested in between with a completely full tank. I have a battery disconnect switch and I turned off the battery in between tests for safety. I stopped when the needle showed the entire full dot. It now works fine. I have not run it down completely to empty, but I have run it down to where I had two gallons left based on how much it took to fill. It seems very accurate.

Matt

Tim, when I get a chance probably Sunday I'll try this. Also thanks for the FS tech information. Steve

Thanks to the other res-ponders also. I'll try all these suggestions. Steve

Thanks for confirming that solution Matt. I haven't tried to correct it yet since I am concerned the arm may not drop far enough to accurately measure empty. It's encouraging to hear it worked okay for you.

I believe the 53 gauge should show full with the sender wire removed and should register empty with the sender wire grounded.

There are a 3 things which will cause the gauge to be inaccurate in the tank even though it worked fine outside of the tank.
1) Float or arm is contacting the side of the tank somewhere along its up and down travel.
2) Float arm needs to be bent. If it reads empty with 2-3 gallons in the tank, bend it downward.
3) Float isn't buoyant enough to overcome the mechanical resistance of the rheostat assembly. These are aftermarket reproductions made who knows where.
How do I know all of this? I have had all of these happen to me, in addition to a leaky float in one case, and a replacement float which fit the arm, but lacked the volume to be buoyant enough to move the float/arm up and down in another.
I am the King of "something is wrong".
Carl

Thanks Carl, I'll try your suggestions. I can't be sure but I think I have the original sending unit.

Yesterday I pulled off the seat back to do some investigating. I gently removed the sending unit and measured about 1/2 tank. When I looked at the gauge , it showed about the same, a little less than 1/2. When I switched on the key the needle slightly moved to the right. Next, I'm going to fill the tank an see if the needle moves any further. I have never had a full tank or really looked that closely at the gauge needle. The case continues....

That sounds very like the problems i've been having Carl,it worked well for about a month,on investigation it looked like the float had become porous,acting like a sponge,I was thinking perhaps it was the amount of methanol in fuel these days breaking the float down.

I haven't had a chance to rectify the problem but have opted to sticking 10 or 20 "fruity Ls" worth of gas/petrol in every time i'm out and about....

Judging by my luck recently,if you're the current King I must be the next in line for the Coronation chair...