Fuel Sender Question

Neil R · 23 August 2010, 22:50

I've recently lost confidence in the fuel sender fitted to my Ribcraft; with the boat sat level-ish in the driveway it's showing 7/8 full, and in fact I've just drained the tank. Even at sea this year, it was never showing less than similar levels, although there was definitely some signal getting through as the gauge did show at least some slight variations around nearly full. In reality, the recent tank-drain says I'd used about 12 out of 20 gals. From memory, the gauge used to be reasonably linear when all was newer.
Anyhow, after a good explore, I can't for the life of me work out how to disassemble the thing etc to do any checking / cleaning / replacement. I haven't even seen anything which looks remotely similar in design on the web. Piccie duly attached (I hope!).
Any clues would thus be much appreciated! I started trying to loosen that side 'nut' (the access and visbility is grotty) - it was only when I went in with a camera did I realise it's actually all welded up, and might in fact be a bolt welded on 'backwards'. (What's that all about?)
The white thing just behind it (forward of it in reality) is the battery box complete with black strap.
Could the shiny part on top of the sender perhaps be significant? It looks like this *might* be the only other moveable part?
I must admit my first reaction is to probably live with it.
This is all as fitted from new about 10 years ago by Ribcraft by the way - no bodges from my end! And they of course will be my next point of contact if we can't unlock this one here.
Also - and this has just occured to me as I've written this - it could of course be the gauge (historically it's been moisture prone). It's the type with roughly 8 leds, such that more of these light up as the fuel load increases. Is there any easy way of checking this, e.g. via applying external voltages?
Many thanks.

Downhilldai · 23 August 2010, 23:07

Looks like a WEMA sender, which threads into the stainless tube.

The bolt is probably an earthing point for the tank.

WEMA sender on ebay:

http://cgi.ebay.co.uk/wema-stainless...Accessories_SM

Make sure you get the correct length

martini · 23 August 2010, 23:22

Agree it does look like a WEMA, a pair of grips on the top should loosen it off, carefully though because it can be easily crushed where the cable goes in.

For a replacement it may be necessary to know the type of gauge as well, some are designed to work with smartcraft, how many other types there are I don't know. Think its all to do with the resistance of the sender, it could end up reading empty when full and vice versa

Neil R · 23 August 2010, 23:23

Indeed it is - many thanks! - the Wema website has a pic of the exact same one, albeit now superseded.

I hope it might just be a sticking / cleaning issue - my boat only goes out a few times a year.

I'd never thought about earthing the tank - but I'm sure you're right there too. I guess this is what can happen when someone other than Ribcraft did the engine and battery install. (I chose to get my engine fitted by my local Suzi dealer in case there were issues).

[Clearly the repair theme is going to be the electrics this year - my Icom 501 VHF has also just died. Last year it was all trailer issues, culminating in a new axle].

martini · 23 August 2010, 23:27

Theres no moving parts on these senders, it's all electronic, it'll just need replacing I think.

Downhilldai · 23 August 2010, 23:48

Quote:

Originally Posted by martini

Theres no moving parts on these senders, it's all electronic, it'll just need replacing I think.

Cylindrical float around a stainless rod, like in the ebay item I linked to earlier? May be sticking, but I doubt it.

Either the sender unit or gauge (or both) will be at fault and need replacing.

BogMonster · 24 August 2010, 00:32

Bad connections can F up the gauge completely because they rely on resistance normally, I had a dodgy connection on my Humber gauge that would read 1/4 full with a full tank, and when you wiggled the connection on top of the sender it would work again. Furry green stuff inside the terminal was the problem, crimp terminal & salt water environment not being the best combination...

jambo · 24 August 2010, 09:50

HI Neil I had to replace my sender two years ago for the same reason but it was fitted by Ribcraft so it was easy getting replacemant. I still get two readings from the new sender one at rest/level and slightly less on the move!!
Hope you get it sorted.

J

Neil R · 24 August 2010, 11:57

Thanks very much to all, I'll report back when I've had a further explore - this might be some weeks away.