Weird gt40 miss/stumbling - please help!

Ran the boat for 40 minutes today. on 4 or 5 occasions during this time I had an engine stumble while on plane and the engine either died or almost died. I went to neutral, the rpm either stabilized or I restarted the engine. I was thinking in my head that my fuel pumps were probably going bad so I headed back to the dock. On a whim I went to town and picked up some contact cleaner, and the returned and disconnected the battery and ecm in order to clean the contacts. I Sprayed contact cleaner on the ecm pins and the harness connector, let them dry and then assembled. I also unbolted the ground connections from the bell housing and doused them in contact cleaner, and re-assembled. After that we ran the boat for about 1.2 hours. Right away the boat stumbled once and caught itself at 1krpm but after that it didn’t miss a beat, I’m back on to thinking the stumble/die issue has been due to a bout of bad gas or water in The gas that worked its way through the system.

I’ve been having similar low power/ stalling issues on a jet ski that I have which I filled up with a Jerry can that was in my garage for 2 weeks during the hot and humid part of summer. I think I put 12 gallons of this same gas in my boat at the time as well.

Hopefully tomorrow is another good day.

Kyle

MrMcD wrote: I had a BMW once that had water in the gas tank We finally cleaned it out using alcohol.   I don't remember what kind we used but I was told the alcohol would disperse the water off the bottom of the tank and help it burn as it traveled through your fuel system..

Mark,
Heet in California?