How does the fuel gauge sensor work

DavidJ

DavidJ

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Hiya
On my S37 at the moment (in Spain) and have just put 100 litres in the port tank. (It was looking low compared to the starboard tank)
The gauge crept up slowly from near empty then suddenly 'wanged' up to near full. Wots happening? How does the sensor work? Some sort of float?
I don't want to take the sensor off particularly to look 'cos I don't want to stink the boat out.
 
ours works with difficulty. Port and starboard never agree until half tanks them somehow they start to match each other. Between half and full they are out of sync by a quarter tank.

I have always assumed they work on floats
 
Some have a float that rise up a fixed column.
Some have a float on the end of a swing arm.
Some are ultrasonic.
Some have little floats spaced up the column.
Some have two columns and measure the resitance between.
I'm sure there are others.
 
and none are that accurate.

I just note the gauge indication each time i fill up, deduct what i put in from the capacity so i have a pretty good idea of what gauge reading indicates what quantity.

My generator pulls from the Std tank so it is always lower and keeps me honest! That one will always stop first.

My T40 gauges are not bad but they don't fall equally even if the gen has not been run and they take identical amounts on fill up. Flying is my legacy and you rely on fuel gauges in a plane at your very real peril. There you have the advantage that 95% of the time you use the same power setting to time has a direct correlation to consumption.

Jeremy
 
DavidJ said:
Hiya
On my S37 at the moment (in Spain) and have just put 100 litres in the port tank. (It was looking low compared to the starboard tank)
The gauge crept up slowly from near empty then suddenly 'wanged' up to near full. Wots happening? How does the sensor work? Some sort of float?
I don't want to take the sensor off particularly to look 'cos I don't want to stink the boat out.
Click to expand...

I think in your particular instance there must have been a bit of resistance on the float arm or float had cockled on the riser which then "jumped" as the float became more submerged giving a bit more lift.
 
What jrudge sez - got my princess installed leccy gauge on the instrument panel, and a me installed sight gauge in the engine room.

Check the sight gauge every time I check oil and strainers, so I KNOW what I've got!

Doesn't answer your question though, does it? ;)

USUALLY, sealine fit a vdo sensor of the swinging float and resistive track type. Usually. Of course, yours will be different..:)
 
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