2005 MS 30 Pilot II fuel sender replacement

I have finally worked down my to-do list to the "Fix the fuel gauge/sender" problem. I was not working when I bought the boat in June; so I installed a quickie sight gauge in the engine compartment and have been ok with that. But there it was that nagging empty reading on the console fuel gauge.

In the interim, the volt meter on my Faria cluster gauge gave out, and I replaced it. While involved in that fix, I discovered a testing procedure for the gauges from Faria which also gave the impedance values for a full/half full/empty tank taken between the disconnected sender wire and ground as well as a gauge needle test. The sender tested bad, and the new gauge predictably tested OK.

So back to replacing the sender and how in the world to get access to the fuel sender. I was able to visually locate the senders on both tanks (yes, there are two - thanks, Mike Shepard for the clue on that), but only one sender is connected to the console gauge.

I had to cut a four-inch diameter access hole under the bench seat on the bridge deck to get to the fuel senders. After getting a visual on the senders, I measured back 8 inches from the forward and outboard 11 inches from the inboard bulkheads of the compartment under the bench seating and drilled a pilot hole to be sure of my location and then easily cut the access hole.

I removed and tested both Wema 17-inch SSL senders and found that the port side sender, which was never connected would give reading which fluctuated between the proper level (I was sliding the float up and down on the sender's rod) and zero, but mostly zero. The starboard side sender's impedance value never changed.

Wema has a website and thankfully has exact replacements. If I need to replace one in the future, it ill be a snap.

Rich,
I noticed those compatrments have an overboard drain. Did you make the access panel water tight?

Yes, I did.

Thanks for the tip. My Pilot 34 is built similarly so I now know how to do it if it is ever needed.


David

That's just what I hope will happen as these senders fail.

I had a talk with the tech at Wema who told me how the unit operates. The plastic float ha a magnet in it, and the magnet closes small reed switches in the stainless steel tube as it floats near the switch. Switches are placed 3/4 inch apart. there are 19 in the 17-inch tubes we use in the 30 Pilot. He said they can fail from several factors like lightning strikes, inadvertent supply of voltage to them, and just naybe age.

Rich,
Was the sending unit that was hooked up on the STBD side tank?

Yes. Port side had never been connected. Once the inspection/access cover holes are cut, it would be simple enough to run another sending wire from the port side up to a point where a toggle switch could be installed allowing you to select which side to read fuel level from. Cost of the 17-inch Wema (now KUS, according to the people I spoke to when I called the number on the Wema website) is 62 bucks.

Interesting, great information. I have never really trusted my gauge fully. From full to 1/2 seems to go quickly. From 1/2 to 1/4 takes a good amount of time. I have never seen it go below 1/4 tank. So now once I hit a 1/4 I'm re-fueling. Do you have a picture or model number of the access panel you installed?
Thanks Jeff.

I used four-inch white plastic, screw-in deck plate/inspection covers from West Marine. They have a six-hole bezel ring and a threaded center plate.

jskinner30PII said:

Interesting, great information. I have never really trusted my gauge fully. From full to 1/2 seems to go quickly. From 1/2 to 1/4 takes a good amount of time. I have never seen it go below 1/4 tank. So now once I hit a 1/4 I'm re-fueling.

Click to expand...

We replaced our original fuel senders, and then the gauges seemed to work fairly consistently over their full range, but we wondered how accurately they showed how much fuel remained. So we carefully worked off almost all the fuel from one side, then fueled up, stopping at every tic on the gauge to write down how many gallons had been pumped. Did this again for the other side, and then later did both again. We then had a very good idea how far down we were from what the gauge showed (it's not linear, and it's not the same from one side to the other). I'm often able to guess within a gallon or two how many gallons a fill-up will take. Results have stayed consistent for 15 years or so.

My tanks are rectangular in plan and vertical cross section, so any reading from a gauge should be linear. Once the new Wema/KUS sender is installed tomorrow, I will be checking the readings of the Faria gauge against my calibrated sight gauge. When I installed the sight gauge on the port side, I took careful measurements of the external dimensions of the tanks and applied a fudge factor of about 1/2 inch to account for their internal dimensions to accurately calculate their internal capacity. I then installed a white-painted board behind the sight tube calibrated in ten-gallon increments for the total capacity of both tanks. If I shut off the starboard tank, the sight gauge level will sink at twice the actual usage as measured on that gauge. The reed switch interval in the gauge is 3/4 inch and just about the same interval as the tick marks on my calibrated sight measure. Hopefully, all will agree. But never trust an electric fuel gauge. A retired trucker friend said one large trucking firm he worked for cut the fuel gauge sender wires on every new truck they bought and issued dipsticks to every driver. Apparently the cost of retrieving dead trucks due to faulty fuel gauges was getting to them.

rgano said:

My tanks are rectangular in plan and vertical cross section, so any reading from a gauge should be linear.

Click to expand...

Mine are rectangular too, but the way the senders work with their pivoting float arm, the gauge reads non-linear.

And, BTW, since my tanks are long fore and aft, gauges read way different when I'm on plane vs slow level cruising.

Yep. The book on this boat says to check fuel when off plane. I like the design philosophy behind these vertical tube, linear sensing Wema/KUS sensors, but I surely am perplexed about the failure of these two.

Nice job Rich.

And I found your sight gage installation particularly ingenious. I'd like to copy it some day. I, too, can't fully trust my fuel gage.

Rich,
Calibrated sight gauge, your holding out on us?
Did you use the existing weld lets for this sight gauge? Is it crossed connected or did you add another connection to the tank? Can you provide a picture?
Thanks Jeff.

I had the same thing happen on my Pilot and fixed it in the exact same manner. I ended up just using the extra sender.

as a extra bonus for access hatch. I got a $200 extra charge at fuel polishing because it was so difficult to remove senders to polish.