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Fuel gauge inaccurate

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jakeandco1958 Commited Dubber

51 posts · joined Aug 2012 ·

#1022835
I have a 1971 Ve beetle that reads only half full when I fill up the tank. To date to remedy this I have done the following. Fitted a brand new gauge, tank sender and voltage stabiliser. All these new parts and still same issue. I have also placed an additional earth wire from the back of the speedo assembly in the event it was a bad earth. No change. I then tried a different power source to the stabiliser. No change. I ran a new wire from tank sender to rear of gauge. Again no change. I'm out of ideas if anyone can help.

ragged Just ask if you need HELP!

478 posts · joined Jan 2005 ·

#1022836
Try putting an earth from the chassis/body to the sender unit. Dave

shokwave2 Officially Full-On Dubber

289 posts · joined Mar 2010 ·

#1022837
Mine did the same thing. I fixed it by removing the sender and bending the arm of it down a bit. That way the lower fuel level pushes the arm up earlier, if that makes any sense. I wouldn't worry what it reads when full, just know what it reads when near empty.

AA003 Custom Title Time!

1,189 posts · joined Oct 2011 ·

#1022838
When replacing the sender unit you have to adjust the arm and the two stops.
I read it on samba, so it must be correct.

Sometimes Volkswagen dealers sell spare parts. Amazing isn't it!😂

jakeandco1958 Commited Dubber

51 posts · joined Aug 2012 ·

#1022839
thanks gents Ill try the earth option first and then maybe the sender one afer that. cheers

Yogie Moderator Custom Title Time!

1,608 posts · joined Jun 2003 ·

#1022853
You need to check what the readings should be for your fuel gauge when full and also when empty. Take out the fuel sender and with your ohmmeter, adjust (bend) the arms until you get the correct readings to match the factory settings. Put the sender back in and you should be fine. Do check the earth first though.

Yogie

nbturbo Veteran Volks Folk

2,171 posts · joined Dec 2002 ·

#1022855
71 VW's I have seen don't have a float arm-its a float inside an ally tube.I had one apart recently and it looks like nothing can be altered.The VW fuel gauges operate between 10 and 73 ohms.You need to select a sender that operates between those numbers.

Yogie Moderator Custom Title Time!

1,608 posts · joined Jun 2003 ·

#1022856
nbturbo wrote:71 VW's I have seen don't have a float arm-its a float inside an ally tube.I had one apart recently and it looks like nothing can be altered.The VW fuel gauges operate between 10 and 73 ohms.You need to select a sender that operates between those numbers.
That could well be true. Our 68 beetle has a single arm with a float on it yet our 72 has 2 arms with floats on them both but our 72 ghia has the cylinder that you describe. Some Kombi's also have the cylinder and I am not sure how to check the calibration for them.

Yogie

modnrod Fahrvergnugen

978 posts · joined Mar 2011 ·

#1022871
For the OP....
The senders have a resistive strip, and as the float goes up and down there is a metal tab that rubs on that strip. When the float is all the way down then putting a multimeter between earth (body of the sender unit) and the output lead it should read about 10Ohms, and when you move the float up it should read about 73Ohms (10-73 as Greg said). Don't be too worried if it reads 4-84 or something, it will still function OK on the gauge.

Oh, and I once had this gauge that did that on a customers car, and I found the needle was just slightly touching the glass and catching. 🤪

vw54 Administrator Always Waiting 4 Friday

16,723 posts · joined Aug 2002 ·

#1022874
How does it read when low in fuel that's more important you don't want to run out
I read it on FACEBOOK so it must be true


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