WEMA Water Quanity Sensor Ohm Reading??

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jefndeb

Guru
Joined
Jun 11, 2018
Messages
601
Location
US
Vessel Name
Indigo Star
Vessel Make
2006 Mainship 400
Hello,

This new to us 2006 Mainship has 2 75 Gallon water tanks and a WEMA dual Quanity Gauge. (1/2 switch) Gauge needle twitches when on Tank 1 and nothing on 2.

I gained access to the Port tank sensor, cut the wires and had 242 Ohms read (pink & black) and the tank is half full...not good,,..According to a WEMA troubleshooting guide I used, 232-252 ohms equals empty, which is what the gauge is showing....I am guessing the sensor is bad but both tanks at the same time?


This what I think I have,..if anybody might know the model/part number, please pass along....


Looking for advice....
 

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Very, very common problem on Mainships of our era, none of them seem to work. I pulled mine out and replaced it with a SOC monitor in the same spot. Measured the water tanks and used a sharpie to mark them at 1/4, 1/2 and 3/4. Sometimes hard to see the water level in the tanks if the light is wrong, but it's foolproof.
 
Issue update - received the new water sensor from fisheries supply, I ordered a WEMA S5U 12 inch,...before i installed it, I twisted the wires together and the display worked...however....i ordered the wrong thread type...:banghead:

i really didn't know if it was NPT or BSP...until it was unscrewed, that was my bad there.....turns out its 1.25 BSP Thread....cant return/exchange it cause the floor is so close to the tank they have to be bent to remove from the tank...I doubt I will be able to remove this new one without bending it.....I knew I would have the same issue trying to install it so I got my extra jack from the truck and ever so gently pushed the tank top lower until I could slip the sensor in the hole.....i thought i was doing great until I tried to thread it in.......oh well...I re-ordered a WEMA S3U 11 inch one so we will see....
 
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