fuel gauge wiring (again!)

I know there was a similar thread a little while ago (but this is different!)

I'm re-wiring the boat just now and including a fuel gauge. This is wired as shown below (hopefully) and is exactly as shown in the vetus wiring diagram.

At the moment, because there's no engine on the boat yet, most of the loom is unconnected.

Rather than have the gauge lights on all the time - ie permanently ingnition powered - I'm wiring them to come on with the nav lights. However what's happening at the moment is that when the nav lights are switched on, the needle on the fuel gauge goes all the way to full (tank is completely dry) and stays there.

What I don't understand is how supply to terminal 1 (on my photo) is getting to terminal 5. As the only connected earth is via the sender unit, I'm having to assume that's how the current is routing.

Terminals 3 and 2/4 are unconnected.

The sender itself has two wires coming from it (blue and brown) and the instructions say it can: be fitted with minus to earth or unearthed (two pole)." I don't really understand what two pole means, so I've done it with a 'minus earth'. I'm assuming it doesn't matter which of these blue/brown wires is supply and which is earth.

Any help appreciated. I'm a bit stumped otherwise. Is this to do with the 'two pole' option on the sender and would it be resolved if an earth was connected to terminals 2 & 4??

41848

I strongly suspect it's your current lack of earth that's causing the problem. Earth problems can be extremely confusing. Try temporarily attaching #2 and #4 directly to your battery negative and see what happens, and temporarily giving power to #3.

cheers for that.

After quite a few days recently devoted to getting the boat ready I've been trying to spend some 'quality time' with the family today -before I get 'told' to:D

I'll give that a go tomorrow morning and see what happens :thumbs:

hmmm. Are you sure one side of the sender should be grounded? On my setup, both wires of the sender connect to the gauge and nothing else.

.. "should one side be grounded" ...

I think it's OK to do so - if only because the instructions say so. As I said, a direct quote from the instructions leaflet says that it can be connected to 'minus earth' or left unearthed (two pole). It's a Vetus gauge though, so I do wonder about the translation of instructions from the original Dutch version.

Maybe yours is done the 'two pole' way - whatever that means?? Actually I wouldn't mind someone explaining that a bit? I'm no electrical engineer, but I have done a bit of car wiring, building in relay circuits etc, and I don't know what 'two pole' means..

(actually... on checking the diagram in the instructions, the second wire from the sender ends in a 'single line', rather than the usual 'earth' symbol of three lines decreasing in size. Does this mean something else I don't know about??)

My understanding of these senders is their should be two wires. One connects to the battery negative the other to the gauge negative.

Then from the guage there should be a connection to the positive of the battery and then the feed from the sender is the variable feed to the negative.

You would also probably have another positive and negative from the guage which is the lighting circuit.

So it sounds to me like you have connected the lighting circuit negative and possibly the positive to the gauge neg and pos which is why it goes to full when you turn on the lights.

I hope this is helpful :)

cheers Chris,

All sounds about right - though I'm not sure about one of the sender wires coming to the gauge negative.

As I say, I've taken my time and done it all exactly as per the instructions which is why I'm a bit puzzled. Def. have not connected the lighting circuit to the wrong place. It's a colour coded wire from the Honda loom, so easy to identify and be sure it's where it ought to be.

Once I've had my coffee though I'll get out there and try rigging up the rest of the connections temporarily so that all the power and earth conections are as they should be and see what happens.

cheers Nos :thumbs:

when I wired up all the connections, temporarily giving power and earth where they should be, the gauge and light worked fine.

Now just the engine to fit.....:D