Wema fuel gauge stuck on full!

craig_c · 19 May 2013, 16:28

It must be lying! I've never seen a full fuel gauge in my life!

Noticed today as we were heading out that the fuel gauge was stuck on full. Had a mess about with it just now, cleaning earths etc but its still stuck.....

I take it I'm going to need a new sender????

macattack101 · 19 May 2013, 16:46

If you can disconnect the sender from the cable try that and the gauge should go to zero.
If the gauge does not move then it is not the sender.
If you have disconnected previously and accidently reversed the polarity then you will get a full indication so it is worth reversing to see if that is the cause.
Hope you have success

Chris Caton · 19 May 2013, 16:57

Quote:

Originally Posted by macattack101

If you can disconnect the sender from the cable try that and the gauge should go to zero.
If the gauge does not move then it is not the sender.
If you have disconnected previously and accidently reversed the polarity then you will get a full indication so it is worth reversing to see if that is the cause.
Hope you have success

it should go to empty when you turn the ignition off ??

craig_c · 19 May 2013, 17:30

It does go empty when I turn the batteries off but straight to full when I turn them on.

Hasn't been touched since the boat was built so I'm thinking a broken wire somewhere.

Chris Caton · 19 May 2013, 18:27

Quote:

Originally Posted by craig_c

It does go empty when I turn the batteries off but straight to full when I turn them on.

Hasn't been touched since the boat was built so I'm thinking a broken wire somewhere.

you would need to check the wiring on your rib, but usually the live feed goes to the gauge, then from the gauge to the sender, then from the sender to earth. It may be worth pulling the wire off the sender that comes from the gauge, see what the gauge does, then touch that wire to earth. If the gauges goes from full to empty, then it's likely to be a sender issue or a short to earth somewhere. Good luck tracing your wiring, most wiring I've seen in ribs and boats in general is horrendous

Nos4r2 · 20 May 2013, 02:27

Which WEMA gauge is it?
If it's a euro spec gauge (0@empty to 190 ohms@full) then it sounds like a bad contact.

The WEMA gauge I just wired is a bit odd-the red is positive, blue is negative, and the black goes to the sender which isn't how most of the online wiring diagrammes show it. The other wires are different colour backlightswhich go to +ve.
The other side of the sender goes to a negative.

biffer · 20 May 2013, 19:16

Give the sender a tap with a small hammer, they sometimes get stuck

craig_c · 20 May 2013, 21:59

that was the first thing i did biffer

a swift tap with a breaker bar but no joy

ill go down tomoro and try to rewire it

craig_c · 21 May 2013, 14:53

Fixed!!!! The sender wire was joined inside a conduit and was totally corroded.

Luckily it went into a junction box before it went into the cab so I simply tested it using a spare bit of wire

Chris Caton · 21 May 2013, 15:51

Quote:

Originally Posted by craig_c

Fixed!!!! The sender wire was joined inside a conduit and was totally corroded.

Luckily it went into a junction box before it went into the cab so I simply tested it using a spare bit of wire

excellent, easy fix

may be worth having a look at the rest of the wiring sometime

nigel52 · 04 June 2013, 11:37

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I have had this problem with the fuel gauge always showing full since I got our RIB in April. I don't know if it has always been like this or not. The boat is about a year old so should not be a wiring corrosion problem. I fiddled around and got no-where so took it to a local marine specialist in France and they said it was fixed but still showing full after two trips out in her.

I have attached a diagram of a before and after wiring but even the 2nd wiring is not working properly. I have done an ohm check and I think the sender is ok but need to bottom out the correct wiring diagram.

Please advise & many thanks. Nigel

nigel52 · 04 June 2013, 12:33

Also I am using battery negative as my earth - is this acceptable and if not what should I be using?

paddlers · 04 June 2013, 13:16

Can you get at the sender to remove it ? I pulled mine out and attatched a length of twin core to it and physically moved it up & down whist looking at the gauge to assess its accuracy ! Provided the float's not punctured it should work in the tank.

nigel52 · 04 June 2013, 17:23

Quote:

Originally Posted by paddlers

Can you get at the sender to remove it ? I pulled mine out and attatched a length of twin core to it and physically moved it up & down whist looking at the gauge to assess its accuracy ! Provided the float's not punctured it should work in the tank.

I wish I could get at the sender but it means the console seating to be unbolted and the cabling and pipework to the fuel tank disconnected and then the floor up. Certainly possible but not an hour or so's job.

Final resort thanks.

Maximus · 04 June 2013, 18:52

Quote:

Originally Posted by craig_c

It must be lying! I've never seen a full fuel gauge in my life!

Noticed today as we were heading out that the fuel gauge was stuck on full. Had a mess about with it just now, cleaning earths etc but its still stuck.....

I take it I'm going to need a new sender????

That IS most unusual!!... Most Wema's I've had were Always STUCK on Empty!

I've given up on Mechanical Fuel ''Gauges'' for that reason!