Fuel Gauge Float

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JSR-69
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Fuel Gauge Float

Post by JSR-69 » 20th January 2022 - 3:56pm

I problem I have come across in the last couple of years which is, I think, due to the dreaded biofuel we now have to endure. Several VW models have a tubular sender in the tank for the fuel gauge and the float seems to be permeable to biofuels. I first came across the problem before the first lockdown two years ago and had taken my sender out of the car because I thought it was faulty. My measurements showed it was working just fine but I eventually worked out that the float wasn't actually floating.

We then went into lockdown and I forgot about it and when I was allowed out again, I put the gauge back in the car to stop the fuel slopping out and was pleasantly surprised to see the gauge working properly again. It must have dried out whilst sitting on my bench. However, after another year or so it has failed again and is reading permanently empty.

I therefore need to replace the float and I don't want to buy a whole new gauge as they are not cheap! I feel quite confident enough to dismantle the sender to extract the old float and install a new one but I need something made from a material that won't absorb biofuel.

Any ideas anyone? I can't be the only one to be suffering ... is everyone biting the bullet and buying new senders?

Judi R
Judi R
1963 Beetle (awaiting restoration)
1972 Karmann Ghia (sold)
1972 412 Variant Auto
1974 412 5-door Variant project

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purplepeter
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Re: Fuel Gauge Float

Post by purplepeter » 20th January 2022 - 5:40pm

Have you seen this? http://home.clara.net/hallvw/fuelsend.htm

I haven't heard of the float becoming porus- might be worth dropping it in a mug of boiling water to check for bubbles
Dave mentions the wires getting gummed up, which might be your problem
Just be warned that the wires are fragile, so the slightest hand tremor whilst playing with the float will cause problems

Simon kelley has new senders if needed

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JSR-69
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Re: Fuel Gauge Float

Post by JSR-69 » 21st January 2022 - 11:29am

Reading Dave Hall's description of the sender was the first thing I did and I have eliminated the traditional problems. I removed the cylindrical cover (very carefully) and the float slides perfectly well up and down and my multimeter gives the expected resistance readings at top, middle and bottom. As a final check, I gently lowered the float into a jar of petrol and it didn't float. After being in the fresh air for a few weeks, the fuel within the float had evaporated and it was light enough to float again.

Judi
Judi R
1963 Beetle (awaiting restoration)
1972 Karmann Ghia (sold)
1972 412 Variant Auto
1974 412 5-door Variant project

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broady_6
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Re: Fuel Gauge Float

Post by broady_6 » 23rd January 2022 - 8:42pm

JSR-69 wrote:
21st January 2022 - 11:29am
Reading Dave Hall's description of the sender was the first thing I did and I have eliminated the traditional problems. I removed the cylindrical cover (very carefully) and the float slides perfectly well up and down and my multimeter gives the expected resistance readings at top, middle and bottom. As a final check, I gently lowered the float into a jar of petrol and it didn't float. After being in the fresh air for a few weeks, the fuel within the float had evaporated and it was light enough to float again.

Judi
That sounds like there is a pin hole in the float and it is taking in fuel. Ive had it happen on all manner of cars over the years. Nothing to do with ethanol, just the nature of submerging plastic in petrol. Your best source of a float I assume will be someone selling a U/S Sender.
The sultan of swing

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JSR-69
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Re: Fuel Gauge Float

Post by JSR-69 » 24th January 2022 - 5:30pm

Hmm ... hadn't thought of that. I have dunked the float in boiling hot water and I have a steady stream of small bubbles from two bottom corners. You may indeed be right!

Judi
Judi R
1963 Beetle (awaiting restoration)
1972 Karmann Ghia (sold)
1972 412 Variant Auto
1974 412 5-door Variant project

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