Fuel gauge help

[Dougster43]

Hoping for some fuel gauge system help. I searched through the forum but didn't find anything that was quite the same.

I have replaced the sending unit, fuel gauge, vibrator, and all wiring on my 73 (Aftermarket - the gauge and sending unit are Classic Line and the vibrator is from Thing Parts).

The gas gauge only reads just above half with a full tank. Verified with 2 different sending units. If I connect the sending unit wire directly to ground then the fuel gauge will read full.

Below about a half tank the gauge seems to read fine all the way down to empty.

Has anyone seen this before? I'm open to suggestions on what to try next.

[sdwalter]

Check the ground between the sending unit and gas tank and gas tank to body. An easy way to check if this is it, is to run a wire between one of the sender screws and the ground tabs on the body behind the headlights.

[74 Thing]

Fuel sender in the tank? Yours is aftermarket so I do not know if the quality is there. https://www.thesamba.com/vw/forum/viewtopic.php?t=655121&highlight=fuel+sender+repair

[JayC]

I have been fighting this same issue since day one with my thing. Even after the restoration, I have not been able to get it to read full. Sorry, wish I had a better answer. I have tried multiple senders, gauges and vibrators with no luck.

I am sure it has to be something in the wiring, but I can't find it.

jay

[Semper_Dad]

Here's a good read on fuel gauge mechanics and diagnostics

http://www.nls.net/mp/volks/htm/fuel_ga.htm
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[Dougster43]

Thanks. I tried the additional ground wire to the sending unit last night but that didn’t change anything. The gauge just seems to reading about half of what it should -,was reading just above a 1/4 tank on the gauge and took 5.5 gallons of fuel to fill it up.

[wbailey2112]

Any thoughts as to if this might just be a mechanical issue and not an electrical issue? You may want to check the float and the arm from the sender to the float as the possible culprit. I would think that there might be an opportunity there to make an adjustment by way of strategically bending the arm (think of the old days when you could bend the arm from the ballcock to the ball float in your toilet tank to adjust the water cut-off and therefore the water level in the tank).

My fuel gauge works throughout the range shown on the dial however it has never been all that accurate or linear in its operation.
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'74 Thing
'83 Westfalia

[blsthng]

Even though it is a new unit, make sure the float is not full of gas.
You can also test it out of the tank

[helowrench]

http://www.midsouthvw.com/TechTips/tech_tip_FuelGauge.htm
This is the same system.
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