Ultrasonic fuel senders convert to Royce or similar, size needed?

[MancaveII]

Well I searched high and low for a matching plug and nothing.

I did fine both the paddle wheel/sea temp and fuel level plugs on both engines, neither of which where going to match up. Without knowing exactly what you call each plug type, the fuel plug off the starboard tank is a six wire (only one used) plug and all the above connectors are three or four wire plugs.

I knew the sensors were working via the ohm meter testing, so I decide to splice a wire into the pink one and connect in to the middle wire on the fuel level plug - bingo, starboard tank immediately registered both nothing out of the port. I trace the sender wire until it was lost in a thick bundle of wires and honestly there's no way to tell where it ends. I searched everywhere in the back of both engines and along the harness for that wire...finally I did the same thing and spliced a wired from that sensor to the middle wire on the port fuel level plug...works like a charm.

Once I find a source for the plugs, I'll undo my temp setup and run both wires instead a protective conduit and match up the factory plug.

It's so nice to actually have the gauges working.

Last thing to tackle is the trim sensors and honestly those I do not worry out. They will get replaced during my winter maintenance and I know I have to calibrate those as well.

 

[William Miller]

Some Good News about the Ultrasonic Senders.
My boat 2006 AJ290 originally had a problem with the gauges and Sea Ray paid the dealer to replace them with the ultrasonic units made by SSI. The first set were configured wrong. The second set were better but I still had problems. This summer I looked into the very expensive royce units and decided to do some of my own leg work. After repeted calls to SSI I got no help. (I came to realize that they are a manufacturing company and just plain don't deal with the public. Then I came upon their dealer who (Listed somewhere before in this thread) who was a huge help. After discussing my isses of erratic readings, they suggested I install "Focus Tubes" that go with the senders. They sell them seperately for about $20-$25. I decided to give them a try and after a month of use, I consider the problem solved. You can look up the part on SSI's web site and order from their dealer. Mine showed up in a few days. They are bassically a flange that sanwitches between the original hockey puck sender and the tank the flange has a plastic tube that you cut to length 1" less than your tank. Mine are 21". Even though mine are very difficult to get to I got both done in about an hour. Didn't need to touch the wiring.... I did have to get longer SS alen head screws to handle the extra thickness of the flange and gasket.

One tip: The bolt holes in the flanges are not set at even spacing around the circle. Both gaskets, the sending unit and the tube flange must all be indexed the same dirrection. If possible put it all together with the bolts installed where you can see it before attempting to get it all the way in the tank. In my case, I was lucky that either the old gasket or the new one had a slight grip on the little bolts. That's the gasket that went on the bottom of the stack next to the tank. It held everything together so I just had to get the whole thing lined up with the tank. Also, take a picture with your phone directly overhead of the sender. It helped a lot to remember which way the sender pointed when I installed it.

In my situation, the Ultrasonic senders were a retrofit so I don't know if or when SSI figured out that they were needed in a Marine application. They could be in some of the boats that were originally fitted with them. I'd like to find out. By the way, there was nothing wrong with the senders. I think there is one of two things happening. Fuel sloshing around or possibly a layer of fuel / ethenol vapor residing on the top of the fuel. One of my symptoms was when the tanks were almost empty (Below 1/4 probaby) at some point they would start reading full.

I hope this helps someone out there.. I'd rather solve the problem than replace something that was "almost" right. I'm glad I spent the $50 at this point.

Keep us posted on what you end up doing!
Good luck!

 

[William Miller]

3 wire senders send a voltage signal back to the engine computer 0-4 (maybe 5) volts depending on the fuel depth.

Two wire senders are like a potentiometer which varies the resistance ohms based on wiper on the old style units or the output of the read style units or even some ultrasonic units.

The high cost of the SSI units is because they each have to be programmed to the tank size and shape. Or maybe they will only do 10 at time. Or probably will give you 1 or two for the cost of 10