Water Tank Level Readings

[Chit Chat]

B37 Cruiser
I don't know if anyone else has experienced this problem but we can't get a correct reading on our water tanks on the main panel. EG the forward one always says 100% - but we have taken out the sensor unit and that seems fine with the correct resistance etc so wonder if there is a problem on the main panel. A marine engineer who has looked at it has basically said its not something he can help with.
Any thoughts much appreciated

[Domi409]

Hello, I had a similar problem with a B37 2006. The wiring was wrong.
My sensor was made of 5 rigid wires of different dimensions: a very short one, a short one, a medium one and two equally long ones.
If you have the same principle, then you can check the system.
The normal way of working is as follows:

The common wire is one of the two long ones. Check with one of them, if not ok, may be the other one.

1. Connect the common with the very short one,  the reading should be 100%
2. Connect the common with the short one,          the reading should be 75%
3. Connect the common with the medium one,                                          50%
4. Connect the common with the other long one,                                       25%
5. Nothing connected , the reading should be 0%.

If by connecting two you can see 25, 50, 75 and 100, the panel is ok and the connection of the wires not correct.
Good luck

[Stevie H]

I had a similar problem and assumed it was the sensor and replaced only to find it was the cable between the sensor and the panel.

[Chit Chat]

Thanks both. We're pretty sure the sensors work as they should - its basically the water that acts as a conductor between the probes. Maybe it is the wiring then as Stevie found. That'll be a harder job !

[Mirror45184]

The top of the rods should also have a bit of heat shrink or similar to stop tracking across base piece. If there is condensate or moisture on the bas and there is no insulation it will create a circuit and false reading.

[SYJetzt]

Had the same issue, caused by calcification remnants on the wet side of the sensor. Cleaned with vinegar, and works since then. To check the system i suggest to plug off the connector of the ribbon cable next to the sensor. If the reading persists at 100%, the error should be at the cable or the panel. If it drops to 0%, check the sensor, if there are any circuits.

[marubio]

Had the same issue. Unreliable level indications. Conductivity varies with water quality, calification etc. always troublesome..
I changed the sensors and meter. I used 240-33 Ohm level sensors, Matching Meter, Cables from old sensors. Meter is direct replacement fit. 
System is totally insulated, stainless steel probes, no problems with grounding etc..
If necessary same system could be used on fuel tank.
Total cost 80Euro app.. Totally reliable.

[nightowle]

Marubio,

where did you buy your replacement parts?

Brad

[Chit Chat]

Thanks marubio.
Yes - please advise where you picked up the kit
Much appreciated

[Domi409]

Hi, With my B45 2010, I had a different problem from the one described here already:
With the sensor block removed from the tank, by connecting with a wire the probes, the reading was correct but once the sensor block screwed in the tank, the reading was wrong.
By looking at the hole in the tank, I could see that it had a too small diameter after the thread causing the probes to touch the tank, causing the wrong reading.
After sanding the hole, the reading became correct.
Worth checking!

[marubio]

Hi, I got the kit / units on Aliexpress.. If you open Aliexpress and search for ""fuel level sensor 0~190 ohm"" you get a variety of sensors and gauges, Gauges marked Fuel or Water, Sensors are varying lengths.
You must know the depth of the Tank for the sensor. Mine were 400mm as far as I remember.
Install Sensors, all screws, gaskets etc are suppied with sensors.
As I said, you only need 2 cores of the 6 or 7 cables for old system. You can throw out the solid state transducer PCB.
The rest of the wiring is in panel, use same tank selector switch etc...
The cables on Meter are clearly marked, +,-, Sensor, back ligt.

Amazon has same units..

Best of luck...

If I do have trouble with Fuel Gauge I'll get the same again....

[Chit Chat]

That's great. many thanks