Fuel Sender Adjustment

[coolbugfan]

Hi Sambas,

I’m trying to get the gas gauge to work in my 1979 Westie. The sender was replaced a little over a year ago but a full tank registers only 1/4 full. At 3/4 full, the tank reads empty and continues to read empty below that level.

My efforts over the last two days to fix this are:

I had the dash out (other reasons) and tested the fuel gauge. Grounding the fuel gauge caused it to read ‘full’. So the actual gas gauge seems to be working.

I have an inspection hatch, so I opened it up and removed the fuel sender unit. It seemed to be fouling against the side of the tank. I plugged it in just sitting in the back of the back with the float positioned at full. I got an about 3/4 reading on the gas gauge.

I reinstalled the sender unit 180 degrees in the tank so it doesn’t foul the side. I know I shouldn’t leave the ignition in the ‘on’ position for too long without starting the engine. I got a reading of more than 1/2 tank before I turned the ignition back off.

So, it’s much better than before. But I’d like more.

Is there any sort of adjustment on the sender or the fuel gauge? Everything now seems free to move and working, but only needs to be adjusted a bit to read correctly. Can it be adjusted? How?

Much thanks!

[dodger tom]

my mechanic sends the gauge, sender, and vibrator as a unit together to be calibrated. did you do that?
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1978 Champaign Edition 2 Westfalia
Would never find the time to keep up another classic air-cooled.

[coolbugfan]

No. Never heard of non-user calibration. What can I do?

[mikedjames]

There is a tiny screw on the back of the vibrator. Turning that changes the voltage . But when the contacs are burned inside , the adjuster does not have enough range to get back to about 5 volts average .

I took mine apart, cleaned the contacts and readjusted it using an oscilloscope to average the voltage over about 1 second..
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Ancient vehicles and vessels

1974 VW T2 : Devon Eurovette camper with 1641 DP T1 engine, Progressive carb, full flow oil cooler, EDIS crank timed ignition.
Engine 1: 40k miles (rocker shaft clip fell off), Engine 2: 30k miles (rebuild, dropped valve). Engine 3: a JK Preservation Parts "new" engine, aluminium case: 26k miles: new top end.
Gearbox rebuild 2021 by Bears.

1979 Westerly GK24 24 foot racer/cruiser yacht Forethought of Gosport.
1973 wooden Pacer sailing dinghy

[dodger tom]

[busdaddy]

[coolbugfan]

.Thanks for the info. Okay. I will take apart the dash again and try the little screw. I thought there must be an adjustment. If that doesn’t work, I’ll be back for plan B. Thanks, Sambas!

[kreemoweet]

Don't USB chargers put out 5 Volts? Could be hooked up in some way to power that gauge?
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'67 bug: seized by the authorities
'68 bug: seized by the authorities
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[SGKent]

buy a new regulator if the old one is hosed. My gauge used to occasionally drop to zero. It was a bad wire going into the regulator. Broken inside the wire housing at the crimp to the brass connector. Drove me nuts trying to find the problem. Just touching a VOM to the connector or spade lug was enough to cause it to show voltage. I'd test the regulated side and no voltage, test the supply and 12V voltage. Replace the regulator and it would work for half a year then die.
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George Carlin:
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Skills@EuroCarsPlus:
"never time to do it right but always time to do it twice"