Question for Anyone with an OEM 20 Gal Poly Fuel Tank

[ThisGuyUKnow]

This is a very specific question for everyone.. I a trying to figure out if my sending unit is bad or not. Currently I dont think I am getting a gauge reading. I have maybe 4.5 gallon in the tank at most. My question is, on a completely dry tank how many gallons does it take before the gauge reads higher than empty. I have taken voltage readings and I seem to be getting good readings at the pink wire at the tank.

 

[Torxhead]

At an empty tank you should get 73 ohms at the sensor. Anyone with CJ gauge issues should have John Strenk's CJ gauge pages:
Basic Troubleshooting for CJ gauges
The new Gauge Page

 

[ThisGuyUKnow]

yeah its not lookng promising. I found that the ground wire from the tank was cut. Not broken, purposefully cut. Ok whatever PO, I tried jumping it with gator clamps. Not getting any OHM readings through the sending unit wires. The meter is reading open however. I am not concvinced this means the sending unit is bad I think its not hooked up. but Since I have to drop the tank either way to continue diagnosing I think I am going to buy a new sender just in case.

 

[Torxhead]

When you remove the tank, this would be a good time to install a door in the bed above the sending unit location. This allows you to change fuel and return lines without dropping the tank, plus make adjustments to the float or replace it when needed.

 

[penster1]

be careful dropping that tank. The PO on my son's jeep overtighten the strap and cracked the tank. Those OEM 20 gals are not made and only available used.

 

[wm69]

When you remove the tank, this would be a good time to install a door in the bed above the sending unit location. This allows you to change fuel and return lines without dropping the tank, plus make adjustments to the float or replace it when needed.

Good functional idea on a heavily modified rig, but if his is anywhere close to original in good shape I wouldn't go hacking up the floor.

It's not THAT much trouble to drop the tank......

 

[k9czar]

I purchased a brand new poly tank with sending unit. I immediately had issues with the sending unit and after some work, I determined the problem with the sending unit, and that was after phone calls with both the dealer and the manufacture of the sending unit. I determined that the one wire on the bottom side of the sending unit, was touching the sharp corner of the frame the unit was mounted to. I was getting 73 ohm all the time thus showing the tank to be empty. Once I moved that one wire away from the corner of the metal, it began functioning properly. I notified the manufacture which included pictures for them to see. I was delightfully surprised by getting a phone call from the owner of that company, thanking me for determining the problem not only with my own, but several others who called with issues that they just could not duplicate in their shop. When he saw the pictures, and the readings, he immediately went to their quality control to address the issue. It came down to whoever was tightening the nut that held that wire in place, was allowing it to twist just enough that the wire touched metal and caused the issue.