mercury 1994 2.5 hp please help!!!

[trappedgenius]

I'll try to make this short... I have very little experience working on outboards. I bought a 2 stroke 94 mercury 2.5 hp about 2 years ago. I ran it on my jon boat a few times but it never would hit the RPMs it should- it was like it was running at half power and it wouldn't run for any extended period of time and wouldn't idle. I didn't touch it at all last year and a few weeks ago I decided it was time to get it going. I did a complete carb rebuild, replaced the old cracked plug boot, new plug, and then it wasn't getting gas. I just installed a new fuel valve and filter(old valve on the on the integrated tank was all gummed up) and put new gas in it. After about 8 pulls it fired up in a bucket (didn't have the prop on) and I took the throttle up and down a few times. It sounded fine, would idle without sputtering, wasn't bogging down like it was before, had good flow out of the pee tube, but it was blowing out a TON of white smoke from the exhaust. All in all it ran for about 3 minutes before i shut it off. I looked at a few forums and it sounded like i just needed to see if it would burn off carbon and old oil so i went to crank it back up and it wouldn't do a thing. Only other thing i noticed was sludge leaking out of the exhaust port in the gear housing. I'm at a loss as to what to do next or where to go from here. Any help or suggestions would be greatly appreciated.

 

[M9.9]

Re: mercury 1994 2.5 hp please help!!!

Hi trappedgenious,
Unfortunately, it seems you may have cooling water getting into the crank case and/or cylinders. The standard I used to go by when it comes to exhaust smoke is: Black=Gas, Blue=Oil and White=Coolant/Water. It's a pretty-ugly affair if that's what the problem is. If the motor was used then stored where the temp could reach freezing and there is water inside the water circulation system, it will freeze and expand and could crack the engine case or blow/break seals; or if overheated warping may have occurred..... If this is the case and you want to save the engine from additional corrosion damage you may want to get it looked at pronto. Good Luck.

 

[impatico]

Re: mercury 1994 2.5 hp please help!!!

So it ran perfect after all that work for 3 minutes but white smoke? then you tried it again and won't start?

as for the smoke, I would run it a bit longer b4 worrying. put the prop on and run it again for 10-15 minutes.

if it won't start, check for spark, but sounds like it's fuel, either not enough or too much.
may have missed something while in the carb.

 

[trappedgenius]

Re: mercury 1994 2.5 hp please help!!!

M9.9: The motor wasn't smoking like that right after I bought it, and i've kept it indoors in south carolina so i know that it hasn't frozen since then. The cooling system is very simple, as it is mainly air cooled. There is an impeller that runs water to a plate underneath the bottom bearing and then right back out so i don't think there's anywhere for water to get stuck. Again, i'm not an expert though...

Impatico: I wouldn't say it ran perfectly, but if not for the white smoke I would have thought that she was ready to hit the water. And now It won't start at all. I drained the carb float bowl--thought maybe it was getting too much fuel or the float was stuck-- and waited an hour or so but still nothing. It was sparking just fine when I cranked it up the first time.

Could carbon build up and old oil residue in the cylinder cause excess smoke? Or maybe the sludge in the exhaust relief port causing exhaust pressure to be too high?

 

[M9.9]

Re: mercury 1994 2.5 hp please help!!!

You mentioned sludge coming out of the exhaust, actually you mentioned all the syptoms of water getting into the case or cylinders. I also mentioned overheating. Are the plugs corroded or sludged at the anode? Are the top of the pistons clean? You might be able to identify if water contamination is the culprit, if not from the above, by using one of the many simple products out there that will detect water as being present.

 

[trappedgenius]

Re: mercury 1994 2.5 hp please help!!!

I forgot in my earlier posts to thank M9.9 and impatico for responding to my request for help, so thank you guys for helping. I really appreciate it.

M9.9, the plug that I replaced last week was old--it was the plug that was in it when I bought it-- but it wasn't corroded or rusty. There was a slight film of black oil on it and it just looked like it was worn down from use. After it ran for the 3 minutes i ran it yesterday i looked at the plug and it just had gas and oil on it. I have no idea how to look at the top of the piston. I looked in the hole where the plug goes with a light and everything looks clean in there... you mentioned products that will detect the presence of water--what would those be? Again, thanks for your help.