electronic know how required

That capacitive type sender has a 4 to 20 mA output so connect your multimeter in series between the sender and gauge on mA (current) meter range the dip the sender in a bucket of water at varying depths noting the current.
 
Rogershaw said:
That capacitive type sender has a 4 to 20 mA output so connect your multimeter in series between the sender and gauge on mA (current) meter range the dip the sender in a bucket of water at varying depths noting the current.
Click to expand...

Thanks for that, but I am not near the boat and I have the sender here, is there anyway to tell if it is crocked without access to the gauge/ boat wiring..
 
Not easily. You will need a 12 volt power supply and a resistor to wire in series so you can measure the current across it, so not a simple thing to knock up at home.
 
Just to rattle on about capacitance fluid level gauges.... They can be used effectively as fuel level guages. They are used always in large aircraft fuel tanks. They have a peculiarity that they measure weight of the fuel. This is because fuel (kerosene) gets lighter as it gets hotter heavier when colder. But the higher density affects the dielectric constant of the fuel so warmer fuel might have a highher level in the tank but shows a similar output as the same fuel when cold (lower level) but more dense. If you are in a jet it is the actual amount of energy in the fuel and weight that you are interested in. Thats what it shows.
Another useful aspect of capacitive gauges is that you can fit more than one capacitive part in parallel. So in a flat tank as in a wing if fuel sloshes to one side one capacitive detector gets less fuel one gets more and it averages out correctly.
The 2 capacitive conductor probes going from top to botom of tank will have one or both insulated for use in water to avert the water shorting out the probes.
They usually have the electronics at the top of the sensor probes out side the tank. The electronics give an output of DC to go to a simple guage measuring the current or voltage.
Hence OP won't have much chance of testing as said unless he can simulate the conditions in the boat. ie DC supply a ressitor a meter and a bucket of water. The encapsulation will mean it is essentially unrepairable. good luck olewill

PS that installation manual has so many "dont do this don't do that" ie don't be stupid, just to cover themselves that it is difficult to sort the important info.
 
Thanks for the replies, my Next trip I'll clean up the contacts, bypass the wiring from the gauge and cross my fingers...... if no good I'll think again. (it looks like it can be taken apart so perhaps simple components inside)

it could well be a fault at the other end. the fuel sender is disconnected, if it is the same type I might try connecting to the fuel gauge and see what happens.

Tony.
 
Other than the wiring to the terminals there isn't much to go wrong, just two insulated parallel wires.

You could test it with a capacitance meter, a local "Radio Ham" may have one.
Another way would be to build an R-C oscillator with the probe as the C.
Finally, there are many ways to measure varying capacitance with an Arduino or other microcontroller.

[Edit] Example of first and last options here and following pages.
 
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All wery nice Nigel but the OP dies not have access to the capacitive element. The sealed electronics on the top of the sender converts the variable capacitance to a 4 - 20mA current loop output.

I have 3 fuel capacitive senders in my fuel tanks and 2 in my water tanks. Mine cane from a supplier to the light aircraft industry in Florida US.

The fuel senders will also detect water in the bottom of the fuel tanks where as a float type will not.

As a bit of thread drift, it may be possible to built a ultrasonic level sensor using one of these

http://www.ebay.co.uk/itm/Ultrasoni...890014?hash=item4af27d7c5e:g:BO4AAOSwuWVWE2q3

Or you could measure the pressure thus depth using one of these.

http://www.ebay.co.uk/itm/310732509589?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT
 
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nigelmercier said:
I didn't see that, where is it?

If that is the case, can it not be powered up with a mA meter on the output?
Click to expand...

The rods that are the capacitor must be insulated from the water at the water will short the rods and the give maximum signal. The electronics must be sealed as if not would prove very unreliable.

Capacitive senders for diesel do not need to in insulated as the diesel is non conductive but if any water in the bottom of the fuel tank contacts the fuel sender it will show full scale in the gauge indicating water in your fuel tank.

This is the type I used for both fuel and water with 4 -20mA output to match the VDO 4 to 20mA gauge for their (VDO) capacitive sender as the OP has.

http://www.centroidproducts.com/
 
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