Tomcat Fuel Sending unit

OffLeash · Posted: Wed Apr 27, 2016 10:28 pm Post subject: Tomcat Fuel Sending unit

Hi All...I need a little help from those with some experience.
I just had my port tank start reading 0 even thought there is about 50 gallons of fuel in it. When I started out today it was working before I added some fuel. not it reads 0 and the Port reads fine.
Does anyone know what sensor the Tomcat uses? I would like to buy one and try it outside the tank before I break the seal for to replace it unless someone has a way to check it without removing it.

The fuel is measured on the Verado system so that could also be a problem but does not make sense because the Starboard tank seems to be reading fine.
Thanks for any help on this
Mike

journey on · Posted: Thu Apr 28, 2016 11:53 am Post subject:

I can only give advice by analogy to a 25. That said, here's what a 25 has. Beats the no reply so far.

An inspection port over the tank mounting hole in the gas tank. Open this port and you're looking at the gas tank and the outside of the sending unit. There is also a sticker identifying the maker. Call that number and ask them to send you a tank sender and a gasket, or ask for two.

You can check the resistance of the sending unit with an ohm-meter without pulling the unit out of the tank. If it's 0 ohms, or open (infinite), it's failed.

That's for a 25, but I can't think that the Tomcat, even with 2 tanks is too much different. You can see photos of the 25 tank installation in my album.

Boris

thataway · Posted: Thu Apr 28, 2016 12:27 pm Post subject:

Do you have separate port and starboard analogue gauges? Or is fuel just measured on the Verado digital display?

Can you see the senders? (either thru the access in the cockpit or under the dinette ?

Since it was working--I would be thinking of a ground issue. But it could be a wire which came loose. The actual sensor has a float, with an arm, which has a small metal strip, which moves over a coil of wire, and changes the resistance,

There are newer types, but I believe in 2007 C Dory was still using this type.

75% of the time a problem is with the wiring,

OffLeash · Posted: Thu Apr 28, 2016 7:43 pm Post subject:

Thanks for the ideas.

I checked the Ohms on the sending unit while it was in the tank, thank for the idea. I also purchased a new generic sending unit about the same depth as what I think is in there now and place the float to what I believe the tank level is. Both show about 15 Oms. I cleaned with wire connections and it still Doesn't work.

The Verado's use digital read outs for each engine and each tank. The starboard is working so I am guessing I will be looking at either a broken wire somewhere along the way unless the problem is buried somewhere in the dark deep mystical electronics and software of the Verado's.

thataway · Posted: Thu Apr 28, 2016 10:08 pm Post subject:

Switch the wire for port and starboard for the Verado readout. That way you can narrow it down--it should show that the verado is working, and it is a wire.

One thing I found on my Tom Cat 255 (when new) was that some of the end to end crimps in the wiring was bad,and did not make a good contact. I would be looking at all of the crimped butt connectors in the circuit.

OffLeash · Posted: Fri Apr 29, 2016 9:04 pm Post subject:

Thanks for the ideas...It was a ground wire.