Help with fuel gauge

[Pmccooey]

To anyone that has the aluminum trunk and aluminum extra large tank. My fuel gauge is pegged at full when I turn the car on. I went looking for the sending unit on the tank and am having problems. Underneath is just the bottom of the fuel tank with a drain plug. On top in the trunk is all aluminum and appears to be riveted on so no access to the top from there. Do I need to drop the tank to gain access? That is if the tank even drops that easy. It’s a large aluminum tank shaped like a U so the sides go up inside the quarter panels.

Thanks,
Pat

[mvanhorn8893]

I would be interested to see the underside of your car. I don't have the big tank or aluminum inner panels but my sending unit is in the front top of the tank and you can reach it for connecting the wires by hand. You would likely need to drop the tank to remove the sender. I'm curious if they removed the fiberglass floor of the trunk or just built the aluminum panels on top of that.
Thanks, Mike

[Pmccooey]

Originally Posted by mvanhorn8893

I would be interested to see the underside of your car. I don't have the big tank or aluminum inner panels but my sending unit is in the front top of the tank and you can reach it for connecting the wires by hand. You would likely need to drop the tank to remove the sender. I'm curious if they removed the fiberglass floor of the trunk or just built the aluminum panels on top of that.
Thanks, Mike

I’ll grab some pictures tomorrow to show you. I have seen other Contemporary’s with the option for the trunk. Not sure if the aluminum tank was an option or custom.

[Pmccooey]

Here are some pictures

[Morris]

The sending unit should be on one of the side pods of the tank on top ...

[Pmccooey]

Originally Posted by Morris

The sending unit should be on one of the side pods of the tank on top ...

Thanks! Is that a picture of yours? I’ll get it up on the lift and see if I can hopefully find the wire connection first so I can test that before dropping the tank.

[Morris]

Originally Posted by Pmccooey

Thanks! Is that a picture of yours? I’ll get it up on the lift and see if I can hopefully find the wire connection first so I can test that before dropping the tank.

It is .....and you need a vent on both sides of the tank as well as a return line from the engine.

[1985 CCX]

The CCX tank is most likely flat so the vents on both side not like it would be for a 40 gallon tank.

I would pop off wheels and check for the sender under a wheel well or worse case drill out rviets as its easy to do.

My HTM car sender is in wheel well access point.

[RockBit]

When I was troubleshooting my fuel gauge, I found that when the gauge sensor wire was grounded, the fuel gauge was pegged to full. You might want to check continuity between your sensor wire and ground.

Here is the thread from my ordeal:

Need help with gas gauge

[1985 CCX]

Also, check to see if it is full.

[Pmccooey]

Thanks for all the help. I had a little time between rain storms to dig into it. Found the sending unit int the middle of the tank towards the front. Ground from the sending unit tested good. Traced the green sending wire to front. It might be pinched on body/frame over by the left rear wheel. I pulled the drivers seat and under the carpet are two wire bundles with connections. I disconnected the gas gauge harness under the seat. Test from fuel tank showing 0 ohms. Tested towards the gauge with potentiometer. Fuel gauge showed E when disconnected. With 0 ohms applied the gauge goes to F, it goes down to 1/2 at 45 and just above E on 90. The fuel tank was drained. I’ll see if I can clear the green wire from the pinch and drop tank to see if it’s getting grounded out on the pinch or somewhere else. To be continued!