Sendin unit issue

[montanamopar]

My 73 Challenger new fuel sending unit measures 72 ohms full at9 ohms empty which Is accurate however at half full its at 54 ohms. My Rally fuel gauge shows empty at 1/2 full. Thoughts?

 

[Katfish]

New unit? I had an old float develop pin holes, and always read low

 

[montanamopar]

New unit? I had an old float develop pin holes, and always read low

 

[montanamopar]

This my second unit both New ,float is fine.

 

[Katfish]

Maybe remove the sender from tank and test externally with gauges so you can see exactly where the arm is. Measured ohms seems correct, so maybe problem with travel inside tank?

 

[marks ebody]

I make sure that the tank sending unit is sitting at the bottom of your tank. The pick up tube could be sitting too high.

 

[AUSTA]

Check the resistance between the tank sender ground & the dash ground you could have a high resistance joint

 

[Coupe]

Units can wear out in the middle of the resistor scale.Keep the tank between 1/4 and 3/4 full and that's where it wares out first.

 

[money pit]

I have the same problem and continue to have the problem. It would read full after filling the tank. I replaced the sending unit and grounded it to the battery. The fuel level was fine with the sending unit outside of the tank. Place it back in the tank, same problem. I even replaced the gauge with an aftermarket gauge (I replaced all the gauges) and I still have the problem. I'm interested in what people say. Thanks

 

[Coupe]

Units can wear out in the middle of the resistor scale.Keep the tank between 1/4 and 3/4 full and that's where it wares out first.

My next step would be... Use temporary, external jumper wires to wire it up in the car, run them all the way back to power and ground, eliminating all original wiring. Like "AUSTA" suggested, sounds like a high resistance open in the wire.

 

[EW1BH27]

Here's a mod I've been doing, don't know if it'll solve the issues here though.

 

[Coupe]

Don't know why, but I can't see your images.

 

[EW1BH27]

Weird. They're YouTube videos. Search Mopar Fuel Sending Unit, I'm: Cruiser. They're both just over a minute.

 

[moparlee]

Weird. They're YouTube videos. Search Mopar Fuel Sending Unit, I'm: Cruiser. They're both just over a minute.

For us non-electricals, can you explain or show in a diagram where that extra wire attaches. What ga wire?

 

[EW1BH27]

Here's a couple pics