Fuel gauge sender

[Laysula]

Half a tank of fuel and the gauge reads full. I have removed the wires from the sender and shorted them across and the gauge reads empty. reconnect them and move the sender arm up and down and no movement, still reads full. So I presume that the sender is U/S. I can fit a new sender easily enough but the only thing puzzling me is that the voltage across the two wires at the sender is only 5.5 volts. (batteries fully charged). Is this normal or have I got further investigating to do?

 

[Refueler]

Further to do ... I have 12v across mine

 

[Skylark]

I believe that some relatively modern systems operate around 5v, Steve.

That said, the first rule of electrickery is “ensure all contacts are clean”

Good luck.

 

[vas]

remove the gauge, clean cables there, check voltages, fit a temp wire from there to sender - or simpler, remove sender and bring it next to gauge and wire them up and check what's going on.

If you get the same behaviour, final test before pronouncing sender dead, is to use a multimeter, switch it to Ohms (small scale up to 500-1000Ω) and see what it gives (sender alone disconnected from gauge/power!) when you move the arm about. If it goes from almost 0 to around 220Ω or so, sender is fine, look at the gauge.

frankly I'd give it a 50% cable and another 49% sender especially if boat is over 20-30yo
On a friend's P45 (80s boat) it's a constant hassle to keep senders working as he's keen to mess about with cables and breakers and often ends up with no power with similar behaviour...

V.

 

[Martin_J]

Useful test information on the Wema website, including confirmation that you've got the EU gauge and sender rather than the US version.. (since your gauge shows full when the sender is disconnected).

How to... Identify a replacement sender I Wema UK

 

[Laysula]

Should have added that the boat is a 30 year old Bavaria and is probably the original sender and gauge.

 

[snowbird30ds]

I can't remember the resistances offhand but asap supplies catalogue tells you for eu gauges, use 3 resistors to check gauge, I think I used 10ohm 90ohm and 180ohm at the sender end (sender disconnected) should show full half and empty ig gauge good.
I have 3 leads somewhere with resistors in and croc clips on each end.

 

[oldgit]

My water level gauge either reads full or empty, from past experience thought that was how they all worked ?
Suspect on this boat the gauge is faulty, you can actually see the sender on top of the water tank at its far extremity , the chances of gettin to it without cutting hole in the side of boat is nil.
It will be simpler to cut new hole and fit new sender at accessable end .
This will probably never happen.
A far more reliable method of knowing when the water has run out is when air starts spluttering out the shower head ?