2004 Merc Outboard 90hp 2 stroke rebuild

VRoss

Recruit
Joined
Jul 26, 2010
Messages
3
Ok...I will try to be brief...but I have had a really stink'n boating season w/this motor. I purchased a 24' pontoon in June from a person who let the boat sit for 2yrs w/out maintaining the motor as in puting fuel stablizer in the tank and you know what those carbs looked like.....anyway he had the carbs cleaned and said this engine is good to go..looks great. purchased the 'toon...now from then I will list what has been done to this motor..thank goodness the guy I purchased from has paid for all of the repairs. I have not had one good day on the water from the day I purchased. The motor would die like it was starving for fuel. would go like crazy and then die to the point that rpm's would not go over 1500rpm and 2 mph...so everyone was pointing at the fuel system.

Carb rebuilt and cleaned.....5 times
all new fuel lines replaced inside motor and outside motor
fuel tank cleaned out and flushed w/some type of sealant to keep debris
from entering carbs
fuel pump rebuilt
spark plugs replaced as one plug had fouled

Lastly just happened this weekend....took the boat out and was dead in water where I had to be towed to the boat launch. time before i was able to gimp back to launch this time...DEAD
Got it back to the mechanic and he tore the engine apart and found that the pistons were fried...scorched for what reason I don't know...he said it wasn't from no oil as there was plenty of oil on pistons. One piston was stuck so badly it almost pulled the sleeve out of the cylinder. The cyclinders are now at a machine shop to be bored...new pistons and internal guts are on order and motor will be rebuilt. The mechanic swears that this motor will be as a new motor coming back from factory, also there was low compression on one of the cyl of 70 which he was aware of before I got it back from him to take out on the water this weekend and the engine was knocking....which I was not aware of. I am asking for advice from the experts...I don't know if I should go forward w/this boat engine once the engine is rebuilt. The gentleman I purchased the boat from said he would give me my money back...HELP!!!!
 

Traceyh

Seaman
Joined
Aug 16, 2010
Messages
66
Re: 2004 Merc Outboard 90hp 2 stroke rebuild

If the pistons were fried, I suspect a very lean condition. Maybe the carbs were not well cleaned. On the engine running good, then dropping rpms would suggest fuel starvation, either from a faulty fuel pump, or clogged vent on tank, or possibly partially restricted main jet (not my first thought).
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,618
Re: 2004 Merc Outboard 90hp 2 stroke rebuild

It sounds as if you have some doubts and you will be hearing all kind of pings/rattles/knocks/spits/farts that the engine will make, sooooooo get your money back and find a boat that is in use and not been setting,you'll be a lot happier:):)
If it engine is rebuilt/broken in correctly it should not have any problems...
 

VRoss

Recruit
Joined
Jul 26, 2010
Messages
3
Re: 2004 Merc Outboard 90hp 2 stroke rebuild

Sorry, so late to reply ..but didn't get a notification of replies to my posting! Top powerhead all put together...yay...still issues...! A friend of mine came w/me when I put the 'toon in the water for the first time since motor was rebuilt ..to my dismay again, engine fills as though it is starving for fuel. Friend swears that the powerpack is or was the issue all along. Power will die down to hardly anything then rev up and just about knock you off your feet then will die down again. thoughts??
 
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