WEMA - Diesel Tank Internal sensor

[sailcapt340]

I have to replace my diesel tank WEMA internal sensor. It‘s reading less than 1/2 a tank of fuel, when I can see I have just over 3/4 of a tank. It‘s not the most dire of issues, knowing the variation in readings I can guess at the fuel level, but would rather not have to.
I removed the sensor from the tank to clean it, but it’s not dirty or fouled. My guess is, it is saturated as it is free flowing out of the tank and gives me accurate readings when I move it by hand.
I also think it might be too short a sensing tube and I have just never noticed the variation before. And the only reason I did notice this issue was because I was in the compartment, saw the level in the tank and then when I looked at the gauge reading less than 1/2, I started to question what was happening.
Are Moeller Sensors more reliable and compatible with WEMA wiring and gauges?
Are there any other sensors being use currently that are better?

 

[dlochner]

Any float sensor is subject to absorbing fuel and becoming less bouyant, Wema (now Kuss) is one of the better ones. The Moeller floating arm sensors a bit more challenging to calibrate and have 2 issues, the float and the elbow with can become fouled and less responsive.

The most interesting sensors are the sonic sensors that Maretron and Blue Sea make among others. The Maretron out puts a N2K signal which can be read on MFD or instrument display.

The most contemporary sender out there is the Gobius C which is radar based. It provides both BlueTooth and N2K outputs. Pricey, but accurate. I have one on my black water tank.

Going old school is the Tank Tender. It relies on air pressure to read the tank level.

If you add a longer Kuss sensor, make sure you have enough vertical clearance to install it. If not you'll have to cut a new hole in the tank. Been there, done that.

 

[sailcapt340]

If you add a longer Kuss sensor, make sure you have enough vertical clearance to install it.

I‘ll definitely check my clearances…….I see from reading the top of my sensor, it is an SSL type and is 11.5 inches long.
While I was hanging head first and waist deep into the access, I just didn’t think to get a ruler and measure the tank’s depth. Stupid, now I have to back and do it again.
11.5” long just seems to short for the tank. But I really feel its the saturation of fuel also.
Thank you for the response.

 

[Ralph Johnstone]

But I really feel its the saturation of fuel also.

Maybe.

Mine has been in service for 26 years without any problems, so no saturation. I think I last poked my nose into it about five years ago and using a laser pointer at night, I could see a fuel level in the tank which looked approximately the same as the gauge readout. The readout will go down to 1/8 tank (not recommended) and all the way up to full again.

 

[Claude L.-Auger]

I have had a Wema for at least 10 years and it is reading fine. Hovever I rely much more on fuel usage based on engine hours of operation. Simple to keep in the log book and determine when you need to refuel. It is much better tnah any fuel gauge. When I stop at a marina to refuel, based on engine hours I can generally tell the fuel attendant with 2 to 3 liters what it will take.

 

[Tally Ho]

I have a Moeller fuel sender and has worked great for the last 10 years I have owned the boat. I expect it was installed when new in 1988… so been working great for 38 or so years.

Greg

 

[Blitz]

Yes, a short a sensor would cause the sensor to read lower than the tank level is, some do this so there is a reserve and others so they don't draw from the last few inches of the tank since it might contain debris.

I have had good success with the wema and now the Kuss sensors.

 

[sailcapt340]

a short a sensor would cause the sensor to read lower than the tank level is, some do this so there is a reserve and others so they don't draw from the last few inches of the tank since it might contain debris.

Good Point….I just changed both fuel filters last week, which both came out clean and no signs of clogging debris. And when I removed the sensor I looked in and the fuel was clear to the bottom, no signs of any gunk. So I’m good in that respect. Didn’t measure the tank though but thats another issue.
When I replace the sensor (I’ll be sure to measure) I think I’ll keep it at the 11 1/2 to 12 inch length to avoid any bottom debris. And just do the math.
I do have to replace the sensor because since writing this post I’ve been to the boat and noticed wide fluctuations in readings. I feel it really is saturated, as the level hasn’t gone down any.
I never really pay attention the gauge, its too low on the panel to see without bending down or sitting right in front of it. So it’s probably been doing this for a while now. And given the fuel I use in a season I won’t be running out any time too soon.