65hp mercury 1969

hey noob here, i just baught this motor off cl, and it runs great when i have the snorkil on it at home it shifts and runs like a champ, but as soon as i get it on the water it only runs about half speed and wont shift? any ideas about whats going on any help would help me out a lot, it a 14foot larson boat its on, could this have anything to do with it not geting up to speed?

Re: 65hp mercury 1969

come on guys please help. any ideas?

Re: 65hp mercury 1969

Could be a few issues. First you should inspect the motor, ie plugs, wireing, water pump, fuel lines, carbs, etc. Finding the solution to a problem is a matter of finding out whats set up right, and what is not. IE if the fuel pump is not working correctly, it would run fine on muffs, but under load, it will die out, from lack of fuel. IN the repair FAQ's there are a few threads you should read, about awaking old motors, and linking and sync inline six's, then post back on what you have done, what you know is right, and then maybe we can give you a better idea. For my money I bet on the fuel system, if it won't idle down under load, its not gona shift right, and it sure won't perform the way those motors can.

Re: 65hp mercury 1969

allright man, thanks a lot for the info, i was kinda thinking it was the fuel too, bit im not that smart on boat motors, im a small engine mechanic so i have the basic idea of the combustion cycle, but on this engine does it have a inline fuel filter, or what? where at in the fuel line system does it fitler the gas? because if the filter is pretty dirty that would cause the lack of power under a load

Re: 65hp mercury 1969

There were no "inline filters" best as I recall. There is a "filter" in the fuel pumps though. MIght be time to get kits for the pumps. There rather cheap. think is like 15 or 20 each. Don't stop there though, check the carbs, the fuel lines, etc. An air leak will lean out the motor, and cause it to run too hot, hot running melts pistons! Pick up a service manual, you can get a cheap cd on on ebay, might be a very good investment.