Sport Jet 90 - Mercruiser

[sjbrush]

I have a 1994 15' sport jet 90. Motor is a 3-cylinder 2-stroke 90hp. This last winter I stored the boat outside with a boat cover. I winterized it properly except for one thing, removing the hull plugs. Needless to say when I picked it up the engine compartment was full of water. I live in Wisconsin so I'm sure it was frozen.

I got it home and pulled the plugs. The top two came out fine but the bottom third plug came out and water followed. So some how water got into the motor. I manually turned over the motor and pumped out all the remaining water. I put oil in the pistons and in the carb throat. I check the compression and its good.

But it looks like I am having a fuel problem. The mechanical fuel pump isn't pulling much fuel. I connected a clear line to a cup of gas and it barely sucks up the gas. I pulled the fuel pump apart and it seemed ok. The diaphragm didn't have an holes in it and everything seemed to be clean.

So I am wondering if the motor isn't producing a strong enough vacuum to pull the gas in because of freeze damage or is the pump just bad. I dont know enough about each one to tell. How can I tell if the motor is damaged internally without pulling it apart? Should I try to start it with a little gas in the piston? My next thought was to put an electric fuel pump but after reading this thread I guess that is out of the question. Any help out there would be greatly appreciated!

 

[Daremo]

Re: Sport Jet 90 - Mercruiser

I have a 95 Bayliner Reflexx with a Sport Jet 90 motor and I went through the exact same problem with mine, except it wasnt covered, it was given to me full of snow, so once it defrosted, I was able to drain it and just like yours, water came out of the bottom cyl.

I asked around a bunch, and everyone said, tear it down. So... I did. If your somewhat mechanically inclined, its a really easy job. The motor weighs 100 lbs. Thats it. I pulled the motor out all by myself with no crane. Took everything off, and pulled the bottom piston. I didnt have the tool to hold the flywheel, so I didnt split the case, but after 4 months of being buried in snow and then water, i only had a couple very minor surface rust spots on the crank counterweight. I have since put the motor back together and im working hooking everything back up.

Bottom line, tear it down, theres no real good way to get a look inside that motor without doing that. Its not that much work, and the flip side is that you KNOW for certain that you wont throw a rod when your 2 hours out on a trip someplace because it cracked a bearing due to rust damage.

Ask if you have any questions, I'll pass on what i know. Knowledge on these boats and motors seems to be pretty scarce.