Fuel Gauge


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Brian

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Joined
Nov 6, 2021
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19
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Hernando FL
Havent done it, but I believe the gauge uses a measure of resistance to show float level.
I am sure I have to apply 12volt to gauge and then a wire would go to sending unit which would vary in Ohms depending on the fuel level. Just not sure what terminals to apply the wires to.
 

Flyer58

YJ Enthusiast
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Apr 12, 2020
Messages
481
Location
Magnolia, Texas
Go to the back left wheel area and look for the wire harness that goes to the fuel pump and unplug it.

You'll see three pins on the, gauge, ground, fuel pump. Different YJ's may vary

With the key on and the plug unplugged the gauge should go to full. If you short out the two pins Ground and Gauge, the gauge needle will drop to empty.

Sorry I don't have the wire color for the ground and gauge because I believe they changed it but as I recall the ground is either pin #1 or #3 and the gauge pin is the one in the middle #2.

The hardest part is trying to get you hands on that plug to disconnect it.
 
OP
B

Brian

New Member
Joined
Nov 6, 2021
Messages
19
Location
Hernando FL
Go to the back left wheel area and look for the wire harness that goes to the fuel pump and unplug it.

You'll see three pins on the, gauge, ground, fuel pump. Different YJ's may vary

With the key on and the plug unplugged the gauge should go to full. If you short out the two pins Ground and Gauge, the gauge needle will drop to empty.

Sorry I don't have the wire color for the ground and gauge because I believe they changed it but as I recall the ground is either pin #1 or #3 and the gauge pin is the one in the middle #2.

The hardest part is trying to get you hands on that plug to disconnect it.
My gauge stays on empty. I have had the tank out and the sender does vary using ohm meter when raising the float. Can one buy just the sender and not the whole pump.
I recently bought this jeep and just working thru the know issues.
 

Flyer58

YJ Enthusiast
Joined
Apr 12, 2020
Messages
481
Location
Magnolia, Texas
My gauge stays on empty. I have had the tank out and the sender does vary using ohm meter when raising the float. Can one buy just the sender and not the whole pump.
I recently bought this jeep and just working thru the know issues.
well that sounds like gauge wire to the sending unit has a short circuit somewhere or isn't getting power. It only takes a few minutes to remove a dozen screws and pull out the instrument cluster. It's very common to have corrosion on the contacts and easy to clean them. I switched out the bulbs for LED's which are much better while I was in there.
 
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Brian

New Member
Joined
Nov 6, 2021
Messages
19
Location
Hernando FL
well that sounds like gauge wire to the sending unit has a short circuit somewhere or isn't getting power. It only takes a few minutes to remove a dozen screws and pull out the instrument cluster. It's very common to have corrosion on the contacts and easy to clean them. I switched out the bulbs for LED's which are much better while I was in there.
OK, Now I have gauge out totally. Needle is on empty. I add pos. and neg to gauge. No change. I manually move needle to full and reapply current....It goes to empty. There is no connection to the sender unit terminal. Should the needle be on full without my moving it. If......it had returned to full, then I would expect it to go to empty when neg. was applied to sender terminal. I think I have a bad gauge.
 
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Brian

New Member
Joined
Nov 6, 2021
Messages
19
Location
Hernando FL
Just for fun I will tell on myself. Got my Z turn mower too close to water and got stuck. No problem says I, I have my jeep! Backed jeep up to mower and chained it. Put it in 4 wheel low and started to pull... What the heck I am just spinning! Recheck shifter, pull again and feel the jeep sinking deeper into mud. Then it hit me (I am 71) I am waiting for front drive shaft u-joints to arrive. I don't have the front shaft in! My wife offers to pull both vehicles out with her Subaru.
 
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Brian

New Member
Joined
Nov 6, 2021
Messages
19
Location
Hernando FL
OK, Now I have gauge out totally. Needle is on empty. I add pos. and neg to gauge. No change. I manually move needle to full and reapply current....It goes to empty. There is no connection to the sender unit terminal. Should the needle be on full without my moving it. If......it had returned to full, then I would expect it to go to empty when neg. was applied to sender terminal. I think I have a bad gauge.
I lucked out and found a whole gauge cluster cheap and used the fuel gauge from it. All is well again.