Rainwater In 1991 Maxum 2100SR

[kcav8or]

I have a 21-foot 1991 Maxum 2100SR I/O with the Mercruiser 5.0 LX/V8 AlphaOne Engine. It's been regularly serviced and maintained, and we're getting ready to sell it. I brought it home and discovered the hard way that our cover is not waterproof. We had a big thunderstorm pass through, and the next morning I noticed water dripping out of the lower unit. The plug was still in. I'm estimating at least a foot of rainwater was collected in the back of the boat. The water probably covered the lower few inches of the engine. I drained all that out and ran fans on it for a couple of days.

After that we took it out to a local lake for a potential buyer to test drive it. It started and idled fine, but once we gave it gas and it started to plane out, it died. It was extremely hard to restart, and I had to pump the choke many times to get it fire. Once it started, I was very busy on the throttle adjustments to keep it running. It finally warmed up enough to idle again. When I gave it gas, it died again. The second restart was still tough, but easier than the first time. We limped back to the ramp.

Back home we replaced the plugs. The old plugs had a few deposits, but were pretty clean. The spark arrestor screen was dirty, so we cleaned that. After this there was no improvement to starting.

I have an appointment 3 weeks out to get it serviced, but that will probably be too late for my buyer, and I'll have to winterize it and sit on it through the winter. Can anybody suggest something for us to try in the meantime?

[mmwjr]

There may be water in the gas. Remove the fuel filter and pour it into a glass jar. Then let it settle and look for a layer of water. You could also try running the engine on a portable fuel tank to see if it runs better.

[kcav8or]

That sounds like a plausible cause. If I find water in the fuel, what's the best way to drain the tank?

[mmwjr]

Water is heavier than gas and will settle to the bottom of the tank. I would remove the fuel that goes to the engine and use an ignition protected pump to remove the water. This pickup pulls from the bottom of the tank so it should initially be removing the water.