Malibu clunky after warming up won't start after

[jondavis08]

Yes, it a Malibu(2006 I-Ride) but it's my father in laws and thought I'd start here for help. Over the weekend he had the boat out and everything was running fine from the first start. After it warmed up the started making a clunking noise so he decided to shut off the engine. After, it would not fire up again. The next day we went to work on it and it fired up with no issue. Took a few ski runs with no problem. After, it started to run hard(but not hot) and turned off by itself. Again would not fire up.

Any ideas where to look?. I feel like it must be fuel related. Everything else I've thought about has been ruled out.

[Evening Shade]

Surely sounds fuel related to me. I would try draining the fuel and replacing the fuel filter/s and see where that gets you.

[Infinity]

Could it be vapor locking? I thot I remembered that being an issue during those years

[Bevostein]

Spark plugs?