1980 25 hp merc. won't run

[boat-anchor]

• Just bought it. changed plugs - 2 year old gas in tank but Ran ok. - When you give it full throttle it boged out then picked up. No real in between as far as throttle. idled great Started good, 3rd pull cold. 1/2 pull warm fired right up. flushed can out and filled with fresh gas stabilizer/ and 50-1 mix. (swepco additive) ran 2times 3.3 gal. 3rd trip out-Now nothing. Only starts with throttle wide open and just barely runs. Will not idle. Cked spark plugs (no electrode version) one was black and oily (fouled out) - the other clean. so i guess running on one cylinder. Now what? I bet the carbs need cleaning and maby some kind of trouble shoot with elect system (first 2 stroke) - what do you think?

 

[The Marine Doctor]

Re: 1980 25 hp merc. won't run

Should only have 1 carb...I would think the problem lies with the ign...that is why you have 1 wet spark plug and one that seems to be firing.<br /><br />If you have access to some wire...you can see if it is indeed spark.<br /><br />Remove spark plugs.<br /><br />Coil output test.<br /><br />Take a normal wire..speaker wire will work fine as everyone has some of that. Place it in the disconnected spark boot so that it will stay there. <br /><br />Next hold the wire about 1/2 inch away from the block. Now pull the engine over. It should spark. <br /><br />Repeat with the next coil.<br /><br />If you find one that does not fire...transfer the + wire from the opposite coil..see if it fires. if it still does not fire..the coil must be replaced. If it does fire then you will have either Points and condensor to change out or a power pack...this depending on model of engine.<br /><br />TMD