2003 3.0 TKS Starts and shuts off after 2 minutes Idling

Hello,

Newbie here. I bought a boat for our cottage and really don't know anything about boat engines. I have a Mercruiser 3.0 TKS on a Glastron boat. I have had it for 3 years now and had no real problems until now. The engine starts beautifully and runs for about 2-3 minutes at idle and then shuts off. It will not restart until it has been left to completely cooldown and then the same circumstances repeat themselves. I have no idea??? Was hoping to find some assistance here.

My first suspicion would be a problem with the needle valve in the carburetor. If it is not allowing fuel into the float chamber, the engine will run out of gas, so to speak. Leaving it to sit allows the fuel in the supply line to dribble past the stuck valve, filling the float chamber sufficiently to repeat the process.
The reason for it to be stuck are many, such as contaminated fuel, dirt, ice, etc and should be looked into if the problem recurs.

Would carburetor cleaner be the first thing I should try? The boat was running fine on the fuel that was in it for the last while.

You really should take the top off the carburetor and inspect the needle and seat. I don't think spraying carb cleaner down the hole will do anything for the valve.
I suspect that upon disassembly you'll find some unpleasantness inside the float chamber. This may be due to poor filtering. The other thing that can happen on these older engines is degradation of the rubber parts due to ethanol in the fuel. The needle valve has a small rubber tip that can be effected by this, along with the fuel supply hose and anything else in the supply system that is (old formulation) rubber.
Nowadays the lines are made of alcohol resistant materials (is it buna-n ?) so it might be time to update the lines and carb parts. Shields Flex-acol is a very good quality fuel line, available here.

I am at the cottage and unable to get any parts from our local dealer so I didn't want to open the carburetor in case I needed parts. I did however take the boat out before it stalled. I ran it for a good 20 minutes with no issues whatsoever until I came back to the dock, put it in neutral and it immediately sputtered and died and would not restart again until it cooled down. Is that still the same problem that you originally thought? Can you tell I'm somewhat afraid to take the carb apart?