French built 2004/5 Jeanneau fuel tank sender resistance

[jwilson]

Having issues with fuel gauge: am fairly confident original 2004/5 age VDO gauge is faulty, but I cannot find a direct identical model no replacement now: newer VDOs have different multipin wiring connectors that appear to need a special tool to wire up, rather than the simple spades on the old one.

If I fit a new Faria or Vetus gauge I need to be confident sender in tank is "Euro" type ie 0 ohms empty - 180 ohms full. The obvious answer is to take sender out of tank and measure but really don't want to mess with this - sealing fittings back into polyethylene tanks is sometimes difficult. Anyone know for sure before I buy a new "Euro" gauge.

 

[macd]

Do you know or can you measure (independent of gauges) roughly how full the tank is? If near-full or near-empty, the resistance should show you whether Euro or US.

 

[tjbrace]

May I respectfully refer you to an earlier post of mine. Might help.
Fuel guage has stopped working

 

[jwilson]

Do you know or can you measure (independent of gauges) roughly how full the tank is? If near-full or near-empty, the resistance should show you whether Euro or US.

That's the problem: I'm not certain any more and not convenient to take the boat to a fuel point. And with 130 litre tank I'm not lugging multiple cans.

The sender reads 7 ohms but the tank OUGHT to be near full, which makes me think the sender (original from Jeanneau France) could be a US one. Meanwhile the gauge when tested with a 200 ohm potentiometer connected seems to work sometimes only, and the needle stays where it is even after the power is off. It's removed from the boat and in front of me as I type and it shows half full. Hence thinking the fault is with the gauge.

 

[RichardS]

That's the problem: I'm not certain any more and not convenient to take the boat to a fuel point. And with 130 litre tank I'm not lugging multiple cans.

The sender reads 7 ohms but the tank OUGHT to be near full, which makes me think the sender (original from Jeanneau France) could be a US one. Meanwhile the gauge when tested with a 200 ohm potentiometer connected seems to work sometimes only, and the needle stays where it is even after the power is off. It's removed from the boat and in front of me as I type and it shows half full. Hence thinking the fault is with the gauge.

If the gauge is showing half full whilst sitting on the bench, I'm sure it's faulty. It might be possible to fix it by opening a gap and spraying in some contact cleaner, perhaps the sort with a small lubricant content, but it's not something I've tried myself.

Richard

 

[peteK]

If its on the bench just connect 12v to it and it may unstick it.

 

[Mistroma]

I imagine it will read 180 Ohm when full. I have just looked at the code I used to calibrate the readings from the sender on my 2009 42DS. I didn't find the max. reading in my notes but see that it read 138 Ohms at about 76% full. It would seem reasonable that max. reading would be 180 Ohms.

The readings are obviously very non-linear and I used different calculations for different resistance readings.
(i.e. 0 - 100, 100 - 115, 115 - 122, 122 - 129, 129 - 138, > 138).

I'm pretty certain that the standard unit on my boat just produces readings based on a linear value between a min. and a max. and wildly out over most of the range.

I keep meaning to replace the sender as it has a tendency to stick above 76% but readings below that are usually within 2-5 litres of the correct volume.

I don't think anyone would claim any accuracy from standard Jeanneau displays and a new sender won't help in that area. It should be more reproducible than your existing unit.

At least the water tank sensor are reproducible on the 42DS but nowhere near the 0%,25%,50%,75%,100% readings reported. I think Jeanneau don't bother with a template and just guess where to fit screws every time.

The water tank unit doesn't produce a varying resistance, the interface outputs voltage in steps and the display just gives the % steps mentioned above.

I decided that it made more sense for the display to say "Between 40 - 79 litres" instead of 40% and programmed my display to show that text.

Fwd. Tank
1.08V Means between 0 and 19 litres 0%
2.28V Means between 20 and 39 litres 20%
3.51V Means between 40 and 79 litres 40%
4.74V Means between 80 and 125 litres 63%
5.98V Means between 125 and 200 litres 100%

1.17V Means between 0 and 4 litres 0%
2.29V Means between 5 and 29 litres 19%
3.66V Means between 30 and 64 litres 41%
4.89V Means between 65 and 104 litres 64%
6.13V Means between 104 and 160 litres 100%

 

[jwilson]

If its on the bench just connect 12v to it and it may unstick it.

Did that yesterday when on the boat. No joy....