Fuel gauge trouble

[dusterglenn]

So how about this. My sending unit reads 11 - 79 ohms when I tested it on the bench. My gauge moves to full when I ground the sending unit wire. I also tested the gauge with the cluster out, and it seems to work.
With the cluster and sending unit both installed, the most it will read is 1/2 full. Almost like it's reading half scale.
What am I missing?

 

[green1]

Check the voltage regulator behind the dash.

 

[74dart]

where is that if I might ask? the voltage regulator? Im having the same problem

 

[RedFish]

factory specs are 9.6 at full and 73 at empty. You're close enough in your reports.
Now my questions and some may seem silly...
How much fuel is in the tank ?
Did you check the float ? Shake it. If you hear or feel anything, it has fuel in it.
When you grounded the sinder signal to get max pointer travel, was that a smooth movement ?
Did you clean and tighten the gauge mounting studs/nuts connections at the printed circuit board.

The voltage limiter is either a seperate can plugged into the back of the panel ( most common ) or inside the fuel gauge ( rallye and others ). That gauge will have 3 posts.
Hope this helps.

 

[RedFish]

one more thing I should mention.... The sender contains a resistor wire wound on a board. The moving contact is brass and has/had a dimple stamped in it to scrub the resistor wire. Because the wire wears the brass, that dimple may now be a hole through.
It will hang on the wire. Your hand would force it contact past the trouble spot while the float could not.

 

[dusterglenn]

Here's some more details.
The sender is around 2 years old. The cluster circuit board has been soldered and repaired in the past, but is the better of the two that I have. All the circuits tested ok. I checked the float, it doesn't appear to have any fuel inside it. When grounded, the gauge moved smoothly and quickly past Full.
With some long jumper wires, I connected the sender up outside the tank so I could watch the gauge while moving the float. With the sender at full, the gauge slowly pulsed up to half, but wasn't stable. The needle was moving constantly.
Does this sound like it's the voltage limiter? It's fairly new too, if I remember correctly. Can you tell I've been fighting with this for some time?

 

[RedFish]

Here's some more details.
The sender is around 2 years old. The cluster circuit board has been soldered and repaired in the past, but is the better of the two that I have. All the circuits tested ok. I checked the float, it doesn't appear to have any fuel inside it. When grounded, the gauge moved smoothly and quickly past Full.
With some long jumper wires, I connected the sender up outside the tank so I could watch the gauge while moving the float. With the sender at full, the gauge slowly pulsed up to half, but wasn't stable. The needle was moving constantly.
Does this sound like it's the voltage limiter? It's fairly new too, if I remember correctly. Can you tell I've been fighting with this for some time?

Sounds like a bad limiter. The limiter does need a good chassis ground which can be the fault since its grounded via the screws that attach the panel on the dash. Plated screws and U-nuts or painted sheetmetal aren't good conducters. A dedicated ground wire from the instrument housing to the car will help, even if a new limiter is the cure.