Fuel gauge above full

Khayhur87

New Member
Joined
Oct 10, 2022
Messages
8
Location
Belton, South Carolina
I am new to the jeep family. Just got a 93 wrangler S. I replaced the fuel sending unit with the 20 gallon unit and a new fuel gauge because it was not working. I also took out the vent pipe in the tank. The fuel gauge is going to be on the full mark when I turn the ignition on and doesn’t move. If I unplug the connector at the tank in short out the wires blue to green it goes back to empty. Fuel gauge does not work when trying to drive. Just stays above full. What can I do to figure out the problem?
 

Flyer58

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Apr 12, 2020
Messages
723
Location
Magnolia, Texas
How much gas is in the tank when you think it should be moving off full? I did the 20 gallon mod and the gauge stays on full until I've used about six gallons.

Fill the tank up and drive 100 miles and you should see it change. Anything over 200 miles and I'd look for a gas station if it didn't move.

There is a chance the float is sticking to the side of the slush trap inside the tank because they tend to warp and catch the float. I had to wrap a piece of sheet metal over the top edge of mine to straighten out the warped sides and keep it clear of the float.
Screenshot 2022-10-13 185553.jpg
 
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Khayhur87

New Member
Joined
Oct 10, 2022
Messages
8
Location
Belton, South Carolina
I did take the vent pipe out. The sending unit is new and is for 20 gallon. I traced the wire back to the dash and all looks good. Is there a way to test the sending unit? I’ve put 120 miles on a full tank after the swap.
 

Flyer58

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Apr 12, 2020
Messages
723
Location
Magnolia, Texas
I did take the vent pipe out. The sending unit is new and is for 20 gallon. I traced the wire back to the dash and all looks good. Is there a way to test the sending unit? I’ve put 120 miles on a full tank after the swap.
You can test the sending unit with an ohm meter. Test between the center pin on the connector and the ground/black wire. You should see somewhere around 90 ohms when the tank is full and 0 ohms when empty. It's a sliding scale so a reading of 45 should be half tank.
 

redbullet

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May 11, 2021
Messages
161
Location
San Jose, CA
I did take the vent pipe out. The sending unit is new and is for 20 gallon. I traced the wire back to the dash and all looks good. Is there a way to test the sending unit? I’ve put 120 miles on a full tank after the swap.
I have only seen the hack where the tube is cut shorter, not removed. Not sure if this is a factor.
 
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Khayhur87

New Member
Joined
Oct 10, 2022
Messages
8
Location
Belton, South Carolina
You can test the sending unit with an ohm meter. Test between the center pin on the connector and the ground/black wire. You should see somewhere around 90 ohms when the tank is full and 0 ohms when empty. It's a sliding scale so a reading of 45 should be half tank.
I just did the sending unit and it read 57. I went to the gas station and filled up the tank with 7 1/2 more gallons and it now reads 90. So that means the sending unit is working right?