Vetus Fuel 12 B Gauge & Sender

[nigelstgeorge]

I have a boat with a Vetus 12B Fuel gauge and sender which is wrongly reading ie empty when full. I have checked the resistance on the two sender wires and they are showing 190 ohms which I think is correct for a full tank. (Actually I think 180 ohms is full but maybe my meter is not that accurate)

I have checked and rechecked the wiring on the gauge and I believe it is correct although do not have a Vetus fuel meter wiring diagram.

Can anyone advise a way of checking the gauge and the sender before I start changing expensive items.

Many thanks

 

[Tranona]

Swap the wires over.

 

[nigelstgeorge]

Swap the wires over.

First thing I tried but all that did was push the needle further over to the left, ie below the empty.

Perhaps I should have said that the needle is in the red /nearly empty part of the dial when full.

 

[srp]

The most common reason is a mis- matched sender/gauge combination. It sounds from your reading that you have a Euro sender, ie 0 ohms empty and approx 180 ohms full, and if it connected to a US spec gauge it will read backwards. The US spec sender will have a resistance of 240 ohms when empty and decrease as the tank is filled.
Swapping wires is not always a good idea unless you know how the sender works - it may have two terminals but one may be the level resistor and the other may be a warning switch, with the body of the sender being the return or negative. There is more on this at http://www.tb-training.co.uk/MarineE10.html#Types of Sender Unit, with details of how to test your sender to see exactly what type it is.

 

[nigelstgeorge]

The most common reason is a mis- matched sender/gauge combination. It sounds from your reading that you have a Euro sender, ie 0 ohms empty and approx 180 ohms full, and if it connected to a US spec gauge it will read backwards. The US spec sender will have a resistance of 240 ohms when empty and decrease as the tank is filled.
Swapping wires is not always a good idea unless you know how the sender works - it may have two terminals but one may be the level resistor and the other may be a warning switch, with the body of the sender being the return or negative. There is more on this at http://www.tb-training.co.uk/MarineE10.html#Types of Sender Unit, with details of how to test your sender to see exactly what type it is.

Thank you for your advice - I would be surprised if there was a European/US mismatch as the fuel sender and gauge were fitted by a polish/uk manufacturer who fit these all the time and the boat is only 12 months old. I have looked the link you sent me which is very good and I will follow some of the guidance. Most of that guidance is generic and may not be completely applicable to my issue - I will still try it all. Failing that it looks like a trip to our local marine engineering company.

(Why I cannot easily take it back to where I bought it from is becuase the boat (RIB) is now in France and I don't fancy a 300+ miles tow plus ferry back to the UK for this issue.)

 

[nigelmercier]

Can anyone advise a way of checking the gauge and the sender before I start changing expensive items.

It seems you have checked the sender, so short the terminals together and watch the gauge.

 

[srp]

Has the gauge always read backwards since new, or is it something that has only just showed itself?

You're right about the giudance on the site I linked to being generic, but it is fairly comprehensive so you might get something useful for it. I have also looked at the ASAP site as they supply Vetus gear, and they also have odd snippets of technical information which can be useful. Are you sure yours is a straightforward variable resistance sender? Vetus seemk to do a couple of different types. The tech support at ASAP is usually pretty good, and if you find the exact model numbers of both the gauge and the sender they might be able to tell you if they are truly compatible - if they are you then know that the problem is down to the wiring arrangement.

 

[nigelstgeorge]

Has the gauge always read backwards since new, or is it something that has only just showed itself?

You're right about the giudance on the site I linked to being generic, but it is fairly comprehensive so you might get something useful for it. I have also looked at the ASAP site as they supply Vetus gear, and they also have odd snippets of technical information which can be useful. Are you sure yours is a straightforward variable resistance sender? Vetus seemk to do a couple of different types. The tech support at ASAP is usually pretty good, and if you find the exact model numbers of both the gauge and the sender they might be able to tell you if they are truly compatible - if they are you then know that the problem is down to the wiring arrangement.

Thanks SRP I have spoken to the RIB manufacturer but they used a sub-contractor to install the sender and gauge; they have used the guy many times and never had a sender failure so think it more likely the gauge or wiring. Cannot see a problem with the wiring and I am getting 191 ohms resistance across the leads.

I cannot easily get to see the model number of the sender but the gauge is: VETUS Fuel 12B.

I think it really is a question of getting a professional to look at it.

 

[nigelstgeorge]

It seems you have checked the sender, so short the terminals together and watch the gauge.

Which terminals are you suggesting shorting together?

 

[Daydreamer]

It does sound as if you have a Euro type sender (0-180ohms) connected to a US type gauge (240-0 ohms). Manufacturers seem to make both types for obvious market reasons.