330 express - fresh water tank gauge issue/sender issue

[Grumpygrady]

Hi

I have an 2003 330 express and have an issue where my fresh water reads only intermittently. I am thinking ground wire or sending unit. Does anyone have the sending unit part number or tips for troubleshooting the issue? how test sending unit etc?

thanks

 

[everwhom]

Here's a thread that may be helpful: https://www.greatgrady.com/threads/water-tank-sending-unit-330-express.29174/

One trick I use in searching this (and other) forums is to use Google with a search like:
"site:greatgrady.com fresh water sending unit"

The "site:greatgrady.com" restricts the results to only that website!

Mine has been out for years, but it hasn't bothered me enough to crawl in there to troubleshoot it. But I just replaced my generator with an inverter setup so maybe I'll dig around down there this Spring!

 

[wspitler]

In 2016 I changed mine on my 2007 330 and as I remember it, it just popped into the tank and didn't unscrew. I have one invoice in my file and it is from KUS in Davie FL for a "S3U-11 Fuel/Water 1.25 BSP 316 ST/ST Sender." Their part number P/N 153099 for $57.38. I also changed one of my fuel tank senders so that could be that invoice as well. Try popping it out and measure the length. They are all pretty standard and it fixed my issue.

 

[seasick]

That S3U sender has a 1 1/4 inch treaded shaft. It is a water tank/liquids unit. The model S3U-11..... is 11 inches but I would strongly suggest you measure the old unit since your tank depth may be different. That said, testing would be the same as for a fuel tank sender, the sender range is 240 to 33 ohms measured with the sender disconnected from the gauge.
Likewise, when disconnected, the gauge should read empty and with the sender wire to the gauge grounded, it should read full

 

[Grumpygrady]

wspitler and seasick - spot on. The part number is from KUS in Davie; 153099. It is the 1.25" screw fitting and 11".

Note to others - it does screw in/out: it is 1.25" threaded. My original one was plastic and toast; the new one is solid stainless steel. Grady part number i was given is 11-211. thanks!

 

[seasick]

Good to know. thanks for filling us in.