Logic Boat Fuel Sending Unit replacement

I have a 2001 17' Logic Dual Console with a 2008 75hp E-Tec. Just took it in for the first service. Got quoted $425 and ended up paying $510, pretty pissed about that. The fuel gauge has not been working since I have had the boat so I told the dealer to go ahead and check it out while he was doing the service. He told me the consoles and the floor had to be taken out to get to the fuel sending unit. This sounded completely ridiculous but he said he called the company and they confirmed it. I just decided to open the access hatch in front of the engine and to my surprise the sending unit is right there and I can grab it with my hand! Wtf, now I'm even more pissed. Just so tired of not being able to trust anyone nowadays. Wonder if he even looked.

Sorry for the rant, my question is if I can just replace this with a universal unit? If I just remove this one and measure the tank depth I should be able to find one that will work correct? Just never done this on a boat before, but I am mechanically inclined as I work on my truck and motorcycle all the time. Thanks for the help.

Re: Logic Boat Fuel Sending Unit replacement

Fuel senders are universal. Get one right here on IBoats. But why not make sure the gauge is ok, the sender wire is ok, the gauge has +12 votls with the key on, the gauge has a good ground, and then test the sender with an ohm meter. Do that by disconnecting the sender wire. Measure resistance from the threaded post to ground. Depending on how much fuel is in the tank the reading should be 33 ohms full, 109 ohms 1/2 full and 240 ohms empty. These are not precise numbers but close enough for the test.

Here is a diagarrm for the fuel gauge system.

Re: Logic Boat Fuel Sending Unit replacement

Thank you for the help. I have no key in the ignition and the gauge is stuck on full. Does this mean anything?

Re: Logic Boat Fuel Sending Unit replacement

Assuming nobody has ever screwed with the wiring on this boat -- yes -- it means something is wrong. What happens when you turn the key ON (run position)? Does the gauge appear to be damaged such as moisture behind the lens, the needle to right of the "pin" etc. Disconnect the +12 volt feed to the gauge (that's the "I" terminal). If the needle doesn't drop then the gauge is likely the problem. If it does drop, then the gauge is being powered all the time and there is a wiring problem. A typical gauge will sit at empty with the key off but some will "float" meaning the needle will rest any point on the dial. You need to check this. Tap on the back of the gauge to see if you can pop it loose. Lets figure out the gauge first and go from there.

Re: Logic Boat Fuel Sending Unit replacement

Ok, I will check it as soon as I have time this week and go from there. Thanks so much for your help! Just a shame that there are so few people you can rely on these days. You know, you think you go to the "professionals" to do the job right but you never really know. Makes me wonder what they actually did for the 3 year service.

Re: Logic Boat Fuel Sending Unit replacement

Silvertip said:

Assuming nobody has ever screwed with the wiring on this boat -- yes -- it means something is wrong. What happens when you turn the key ON (run position)? Does the gauge appear to be damaged such as moisture behind the lens, the needle to right of the "pin" etc. Disconnect the +12 volt feed to the gauge (that's the "I" terminal). If the needle doesn't drop then the gauge is likely the problem. If it does drop, then the gauge is being powered all the time and there is a wiring problem. A typical gauge will sit at empty with the key off but some will "float" meaning the needle will rest any point on the dial. You need to check this. Tap on the back of the gauge to see if you can pop it loose. Lets figure out the gauge first and go from there.

Click to expand...

Just disconnected the "I" terminal. Gauge still stuck at full, past the last line. Tried it with key on and off.

Re: Logic Boat Fuel Sending Unit replacement

might be worth $12 to go get a universal fuel gauge and just plug that in as a test if you have a fancy all in one dash. if its just a gauges bolted in from the back then just get one the same size. i agree with silvertips i think its 99% sure you have a bad gauge

Re: Logic Boat Fuel Sending Unit replacement

If the gauge is stuck on full with no power it is toast. You might try a little l;ove tap with the butt end of a screwdriver to see if it will jar loose. But even if it does come loose, chances are it still an unreliable gauge. They are not budget busters to replace.

Re: Logic Boat Fuel Sending Unit replacement

I am in the same boat (get it?...yes pun intended) as this guy. Fuel gauge stuck at full when ignition is off. Guess I will buy a replacement for it.

Re: Logic Boat Fuel Sending Unit replacement

I finally got around to replacing the gauge and for a few minutes I thought it had fixed it as the gauge actually moved. It never started working correctly though so I just pulled the sending unit and it looks pretty old and toasty so I'm gonna swap it out. My issue is that my unit has 3 wires, not 2? I traced the third wire and it leads to the fill hole? Anybody know what this is for?

Re: Logic Boat Fuel Sending Unit replacement

Just did some more research and I believe this is a ground wire for the fill neck. I will run it under one of the new sending unit mounting screws.

Re: Logic Boat Fuel Sending Unit replacement

There should be three wires. The pink wire goes to the threaded terminal on the sender and then up front to the "S" terminal on the gauge. The metal flange of the sender must be grounded. The third wire you mention is a ground wire for the (apparently) metal filler neck.