Unwinterizing a boat after 18 months

Repair or modification of Boston Whaler boats, their engines, trailers, and gear
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Joined: Mon Apr 29, 2019 8:09 am

Unwinterizing a boat after 18 months

Postby footy3 » Mon Apr 29, 2019 8:11 am

I have been tasked with selling my father in law’s 1986 OUTRAGE 18. He's just not capable of using it anymore. It was put up for the winter in late 2017 and wasn't run at all last year. He has always been very strict about putting stabilizer in the fuel. I'm not sure if he fogged the engine, a 20-year-old Honda 90 four-stroke-power-cycle engine. I know it ran fine when he last used it, about 18 months ago.

I plan pull the spark plugs, spray some kind of lubricant in the cylinders such as WD40, PB blaster, two-stroke oil, let it sit for a while, spin the motor with no plugs, then put in clean plugs.

I may also drain the fuel tank—about 60 gallons.

In what way can that fuel be disposed? I may put in 5-gallons of the old fuel at a time in a fresh tank in my F150.

I will charge the boat battery, add fresh fuel, and see if the Honda 90 engine fires up.

Give me your thoughts.


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Joined: Fri Oct 23, 2015 6:58 am
Location: Nova Scotia

Re: Unwinterizing a boat after 18 months

Postby Don SSDD » Mon Apr 29, 2019 8:32 am

If there is a fuel-water separator filter, change that filter. Pour the filtrate into a clear container and see if any water is in it.

Disconnect the fuel line at the primer bulb. Siphon some fuel out of the tank using the fuel line. Check the smell and colour of that gasoline compared to fresh gasoline. If it’s really stinky and dark in colour, dispose of it. If okay or only slightly off, drain the tank and check it for water. Then slowly add the old fuel to the F150 after removing the water.

I did this in my Outrage when I had a bad fuel tank and got water in the fuel tank.

You could get the Honda running using fresh gasoline in a portable tank to eliminate risk of bad gasoline, then deal with the fuel tank and old gasoline.

I’d squirt a little motor oil in the cylinders and roll the flywheel with the plugs out—not too much and I wouldn’t use any of that other stuff in the cylinders.
1986 Outrage 18 with 2001 Honda 130 HP
Former Owner 1991 Guardian 19 with 1994 Evinrude V4 140HP
Former owner 1987 Montauk with 1998 Mercury 90HP
Nova Scotia

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Re: Unwinterizing a boat after 18 months

Postby jimh » Mon Apr 29, 2019 9:02 am

If the gasoline was stabilized, the 18-months of storage should not be a problem unless there was subsequent water intrusion.

Only use TCW3 oil to lubricate the cylinders.

A lead-acid battery of unknown quality and age, left uncharged for 18-months, and perhaps connected to unknown parasitic loads is unlikely to be very useful. Considering the cost of a replacement battery will be about $200 or less, a new battery will be a good investment and will remove the battery as a source of problems in the restoration of the boat to operating condition.

On the other hand if the battery is a $350 premium-quality ultra-high-purity lead AGM battery that was left at full charge, had no parasitic loads, and is only a few years old, it should still have substantial stored charge and may only need to be restored to full charge.

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Re: Unwinterizing a boat after 18 months

Postby Jefecinco » Mon Apr 29, 2019 9:47 am

Charge the battery if it will take a charge. Replace if needed. Check the oil and add if needed. Check around the engine lower unit for signs of an oil leak. Check level if leakage is detected. Connect a source of cooling water. Pump the squeeze bulb until it becomes hard. Start the engine and run it at idle until the engine warms up.

Don't worry too much. The Honda is not delicate.