Fuel Gauge Question

[Lccountryboy89]

I have a 1987 M35a2 that I recently purchased and I'm having problems with the fuel gauge. The needle on the gauge is always to the right past full. I'm wondering if I'm going to need to purchase a new fuel gauge or the sending unit that is in the tank?? Are there any quick tests or tricks to know which one I am going to need??


Thank you for the help!!

 

[ke5eua]

I have a 1987 M35a2 that I recently purchased and I'm having problems with the fuel gauge. The needle on the gauge is always to the right past full. I'm wondering if I'm going to need to purchase a new fuel gauge or the sending unit that is in the tank?? Are there any quick tests or tricks to know which one I am going to need??


Thank you for the help!!

Add a ground wire from the sending unit to the frame. These trucks are terrible for grounding on the tanks.

Here is how mine are. You only have one tank but same concept.

 

[Lccountryboy89]

Truck already has a ground wire. Will double check and make sure it's actually grounded tho!

 

[ke5eua]

Truck already has a ground wire. Will double check and make sure it's actually grounded tho!

If it is grounded ohm it out and see if it is within specs.

Another options to check the gauge is to get respective resistors and put in place of the sending unit to see if it is working correctly.

 

[cattlerepairman]

Also check the sending unit arm and float in the tank and ensure it actually moves.

 

[3dAngus]

Or, PM me your address.
I'll pull one off one of my instrument clusters and you can test it to see if there is a difference. You can just send it back when done.

 

[3dAngus]

Hey Roger,
So I'm sending out a confirmed good fuel gauge. Please return when done as it completes my Instrument panel.
I agree with those above, you likely have a bad ground somewhere. Make sure you Instrument panel is grounded with an alligator clipped wire if you have it removed when testing. You can just ground it back to chassis, but you should run continuity to make sure it is good. Someone already put a new sending unit on there. They might have made things worse in doing so.
Hope this helps. My return address is in the box.

 

[wreckerman893]

The only thing that lies more consistently than a career politician is a military vehicle fuel gauge. I use the dipstick method myself......belt and suspenders you know.

 

[ke5eua]

The only thing that lies more consistently than a career politician is a military vehicle fuel gauge. I use the dipstick method myself......belt and suspenders you know.

I just replaced both sending units, but carry a paint stick with me as a backup.

 

[Jeepsinker]

I just open my fuel cap and look. If the fuel level is below the strainer, it is time to fuel up if I can.

 

[SCSG-G4]

I just open my fuel cap and look. If the fuel level is below the strainer, it is time to fuel up if I can.

I prefer to never let it get low enough to see the strainer. The tank may hold 50 gallons, but there is less than 40 that is usable on anything but flat ground.

 

[ke5eua]

I prefer to never let it get low enough to see the strainer. The tank may hold 50 gallons, but there is less than 40 that is usable on anything but flat ground.

On my trip from San Antonio I filled up both tanks and didn't fill up till I got home. I figured I had about an 1/8 in each tank.