fuel gauge reading half full when full

[Steveyg]

Relatively new owner to a 74 Bay Window. When full, the tank reads half full and measures empty when half.

Ive read a few threads stating the opposite issue, so not sure if the same trouble shooting applies. Check wire from fuel sending unit to gauge, replace sending unit, replace gauge?

Is there a way to calibrate the gas gauge and ideally leave it in the dash to do so?

[Starbucket]

Go to Jbugs.com and buy the sending unit with the wire arm so you can put a gallon and a half of gas in the tank and bend the arm to read on the E then you will have a reserve. The tower sending units are not adjustable and from China so quality control is a foreign word to them.

[busdaddy]

A 74 should already have the arm style sender, but is it OG or aftermarket, time for some testing:
https://www.thesamba.com/vw/forum/viewtopic.php?t=701705
https://www.thesamba.com/vw/forum/viewtopic.php?t=735100
https://www.thesamba.com/vw/forum/viewtopic.php?t=381486

BTW, the arm sender does not fit 68-73.5, totally different system.
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[vwwestyman]

My late '73 (so same style sender as yours) does the same thing. I've mostly decided I dont' care that much about it, I guess. Filling the tank reads 3/4 on the cluster, and the needle is way left of the empty line before I'm out.

I've decided I mostly don't care, at least by my inaction. I suspect there is a ground wire that is kind of dirty but don't really know for sure.

At least this way, I haven't run out of gas!
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Dave Cook

President, Wild Westerner Club

1978 Champagne Edition Westy, repowered to '97 Jetta TDI
1973 Wild Westerner
My Thing

[cmonSTART]

If you really care about it being reasonably accurate look up some of the posts on how to cut a sender access hole. That way you can remove the sender and bend/adjust the arms and stops to make it more accurate. (It is possible without the hole, but the whole tank needs to come out.)

It took a few rounds with mine but I got it reasonably close. It's not difficult.
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'78 Bus 2.0FI
de K1IGS

[Steveyg]

[KentABQ]

[cmonSTART]

I used a 4" hole saw to cut it, and a 4" stovepipe plug with some silicone to close it off.
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'78 Bus 2.0FI
de K1IGS

[SGKent]

also lengthy discussion here https://www.thesamba.com/vw/forum/viewtopic.php?t=693930

keep in mind that the unit has to warm up before it stabilizes.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[wagohn]

We cut the hole in summer, and glad we did. We had to tweak the arm of the sender multiple times to get it "just right". We cut a 4.5" hole.

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1976 VW Transporter, 2.0 FI Engine

[igotta40]

I would say that having access to the sending unit without having to remove the motor would add more value than lost due to cutting into the floor. I have the same proble, reading 3/4 when full. I have a Jan 1973 with a tube sender. I’ve had two gauges and 3 senders just to get it reading the way it is. It’s frustrating.

[Mispeld]

You can lay the firewall on the engine and slide the fuel sender over the tank and through the pie hole. It's really not that bad. I did it twice because of a garbage Chinese sender and O-ring. Took less than an hour the second time.

I was too lazy to cut a hole and fab up a cover.
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Tom
1977 Westy. 2.0 Fuel Injected.