Fuel Gauge always shows Full

[PanamaJet]

Put gas station fuel in the boat twice, fuel gauge works fine.

For the third fill up, I got Ethanol free marine fuel at the marina. Since then, the fuel gauge is stuck on F.

Did the 4th fill up at another marina today - fuel gauge still stuck on F.

This is a 2017 Scarab 215.

Any ideas?

 

[Pirana]

I highly doubt that it has anything to do with the ethanol free fill up and more with something just a coincidence. but thats just my opinion.

 

[Murf'n'surf]

Not sure what type of fuel sender Scarab uses but here is some knowledge..... Pull sender out to see if the float got stuck. If its not a float style and is a capacitance style you might have water in the bottom fuel layer. Some sender units that operate on resistance will peg full if it detects water.

 

[Murf'n'surf]

Does the gauge stay of full when ignition is off?

 

[PanamaJet]

Not sure what type of fuel sender Scarab uses but here is some knowledge..... Pull sender out to see if the float got stuck. If its not a float style and is a capacitance style you might have water in the bottom fuel layer. Some sender units that operate on resistance will peg full if it detects water.

What is the procedure of pulling out the sender? Can I do it at the dock or it has to be on the trailer?

 

[PanamaJet]

Does the gauge stay of full when ignition is off?

Whenever the display is on, the gauge says Full, regardless of whether the engines are running.

 

[Murf'n'surf]

You can pull the sender anywhere. Find the access to the top of your tank. Usually under the floor somewhere. There will be 5-6 bolts to remove and the sender will pull straight up out of the tank. Once the sender is out in open air it should read empty. Unplug the sender and it should read empty.

Careful if your tank is full, you might want to wait so no fuel spills out of the sender opening when you remove it.

 

[Rick215HO]

What is the procedure of pulling out the sender? Can I do it at the dock or it has to be on the trailer?

Have you run your boat at least half tank to make sure? The gauge typically does not start moving until a good amount of fuel is consumed. The sensor is in the back of the tank so it takes a while.
It is a resistor type fuel level, 4.8 ohm full 89.8 ohm empty. You may want to check this first to make sure dash is not your problem (unlikely).

On the Scarab you would be pulling a unit that contains the submerged fuel pump, the filter, and the level sender all together. It may require disconnecting high pressure fuel lines to engine.
When you open the hood and look at the fuel tank you will see two large round ports where the fuel lines come out of and have electrical wires coming in. One of those units have 2 pink wires (level) and 2 power wires (pump), that one should have the sender there.

There is a special tool (fuel module socket) to grab the entire assembly and rotate it to pull out and install. Note that there should be alignment marks in the fuel tank whenever you reinstall the assembly. When you open this assembly you will have a hole about 6+ inches dia. on your tank. Careful with fumes, spills, you probably want to do this out of the water imho.

IMO, as much as I like working on my boat, I probably would leave this for a pro-shop in my case, and have them run a pressure test of the fuel system afterwards.

 

[PanamaJet]

Have you run your boat at least half tank to make sure?

[ ... ]


IMO, as much as I like working on my boat, I probably would leave this for a pro-shop in my case, and have them run a pressure test of the fuel system afterwards.

Yes, I got it to about 25% full for testing.

I agree. It very much sounds like something that the dealer can handle under warranty.