Fuel Tank Sending Device

Maine Sail · May 12, 2013

bobcat30 said:
I replaced the Fuel gauge this spring. When I turned the power on, it registered one time and then stopped working. How do I test the sending device in the tank? How difficult is it to change the old one out?
Thanks,,, Bobcat30

Place an Ohm meter across the center stud of the sender and the mounting flange. You should get a reading between 33 & 240 Ohm's

KingAirDriver · May 12, 2013

You could also take the two leads and touch them together, that will cause the fuel gauge to read full.

I thought I had a bad gauge, buddy of mine told me to test it with this method, and lo an behold, the gauge was good, the sender was bad.

I think the two wires are yellow and gray. I don't recall if I took the one that was just pushed onto the ground position and touched it to the center terminal on the sender or vice versa.

Perhaps someone else can jump in on here and clarify.

shipwreck66 · May 12, 2013

When I pulled the old sending unit out of mine it was almost discintegrated. Now I'm either full, which I think I am, or I'm getting a faulty reading. I had to dremel out a little half-moon piece to get the sending unit out, it's held in by about 8 machine screws on the top. Apparently the tank was slipped in as a complete unit during construction and they gave no thought to what owners years down the road would encounter in replacement.

KingAirDriver · May 13, 2013

I had a heck of a time myself swapping the sender out. I didn't cut the glass apart, but I did take the sender itself apart and put it back together in place. Tough 2 hour job...
Also on the 27...

Anonymous 121765 · May 13, 2013

My 1980 C30 had a tank top gauge from the factory. I used this for a number of years until I repowered.

I also replaced my old demure panel with the Admiral panel with all the bells-n-whistles. I put in a new sending unit and wired it to my panel gauge. Worked for less than a year.

Replaced it with a different make sender & it lasted less than a year. The wiring is correct, the gauge is good, & wiring so WTF?

I still had the old tank top model & put it back. I never have a problem. I have to move cushion & access cover to read, oh well.

Has anyone had this type of problem?

CR

hvbaker · May 13, 2013

Capt Ron,

I had a similar problem and it turned to be a faulty ground.

Maine Sail · May 13, 2013

captnron said:
My 1980 C30 had a tank top gauge from the factory. I used this for a number of years until I repowered.

I also replaced my old demure panel with the Admiral panel with all the bells-n-whistles. I put in a new sending unit and wired it to my panel gauge. Worked for less than a year.

Replaced it with a different make sender & it lasted less than a year. The wiring is correct, the gauge is good, & wiring so WTF?

I still had the old tank top model & put it back. I never have a problem. I have to move cushion & access cover to read, oh well.

Has anyone had this type of problem?

CR

Buy an electric sending unit capsule for the tank top gauge. Other than WEMA senders these are the absolute most reliable sending units made.

A mechanical gauge, with the magnetic sending capsule is the Cat's meow.... It is what I use on my own boat... The sending units with the mechanism submersed in the fuel SUCK and are horribly unreliable. I will not install them for customers even if the beg...

A WEMA sender or mechanical with external sender are all I will use for fuel....

Piratenorm · May 16, 2013

Maine Sail said:
Buy an electric sending unit capsule for the tank top gauge. Other than WEMA senders these are the absolute most reliable sending units made.

A mechanical gauge, with the magnetic sending capsule is the Cat's meow.... It is what I use on my own boat... The sending units with the mechanism submersed in the fuel SUCK and are horribly unreliable. I will not install them for customers even if the beg...

A WEMA sender or mechanical with external sender are all I will use for fuel....

Maine Sail, do you have a make and model number for this sending unit? A supplier as well? West Marine (the most convenient place for me to shop where I live) has one. Thanks.

Maine Sail · May 16, 2013

Piratenorm said:
Maine Sail, do you have a make and model number for this sending unit? A supplier as well? West Marine (the most convenient place for me to shop where I live) has one. Thanks.

The Moeller mechanical senders look like this, your order by tank depth:

You then add this "conversion capsule" Moeller part #035760-10

Or you buy a WEMA sender for your depth tank. Moeller just re-sells the WEMA units:

You don't buy this style! This is a horrid piece of junk:

Piratenorm · May 16, 2013

Ah, Thank You! And avail. at W.M. as well. As always, M.S., you are The Answer Man!

DanM · May 17, 2013

Lots of great advice in this thread, but it reminds me of an old topic.

My C30 (#4328) probably has the sending unit that MaineSail hates, and it indicates more fuel when the engine is running versus when the engine is shut down. The only variable I can think of is the voltage (higher when the engine is running). Is the engine running voltage (higher) the reason for the higher reading?

Thanks! DanM.

Maine Sail · May 17, 2013

DanM said:
Lots of great advice in this thread, but it reminds me of an old topic.

My C30 (#4328) probably has the sending unit that MaineSail hates, and it indicates more fuel when the engine is running versus when the engine is shut down. The only variable I can think of is the voltage (higher when the engine is running). Is the engine running voltage (higher) the reason for the higher reading?

Thanks! DanM.

Should not be, unless you have a faulty gauge. These senders are resistance readings not based on your system voltage... 33Ω is full and 240Ω is empty...