Hey all! I'm in the process of getting some boat motors going for my mom's boyfriend (yeah....I plan to use it too), and am thinking I am chasing a spark related issue on a '74 9.9 Johnson. This was a $40 garage sale find, the guy was told by a shop that it needed a waterpump. It had not been run in over a year, but the guy claimed it ran ok. Because it was between this and a 1965 merc 110 freebie with an issue that was unknown (been passed between several people and info forgotten), I elected to start on this one since it was said to run. I pulled the bottom leg and found the pin that holds the impeller to the shaft had somehow come out of place. I cleaned it all up, reassembled and went on trying to get it running. It took a long time to get it going and was hard on the arms (for some reason it feels unusually difficult to pull), but I did prevail. It seemed to run poorly so I got new plugs and tore down the fuel pump and the carb (which was oddly pristine inside). I also did a compression test and got numbers around 65# (3 pulls). After a little run time to clear up it seemed to improve but did not idle well and seemed hesitant at higher rpm. I noticed some bubbling at the cylider head and found some loose head bolts, brought the compression to around 75#. I decided to take it out fishing to get some run time on it and see what I would come up with. Off the bat it ran and got the boat moving ok, though slow for a 9.9. It seemed best at about 3/4 throttle. At WOT it seemed to surge in short cycles of about 2 seconds, it would sound to run smooth and pick up a bit of speed and then kind of sputter. I ran it about 10 minutes till I got where I was going and then left the trolling motor take over. After an hour I decided to try the other side of the lake and had a heck of a time getting it running. When I did, it seemed to have reduced power. Getting across the lake took about 5 minutes and I shut it down again. The bugs on this side were terrible and after about an hour I decided to go back to where I left off on the other side and troll back to the boat launch. This time getting it running was a nightmare, it took putting it in gear at full throttle to fire up. Again, power was further reduced and gradually got worse as I went, to the point that at WOT it was barely at a fast trolling speed.
After returning home I pulled the plugs and found one to look maybe a bit on the rich side while the other was still quite shiny and wet (#2 cylinder IIRC). I thought maybe I had lost compression so did another compression test, this time coming up with between 75-85# through my 3 attempts. Grounded the plugs and pulled it over with the lights out, both plugs look to spark ok. Pulled the flywheel and found #1 points to be around .025 and #2 to be .020. Both sets of points look ok, so I set #1 to .020, and that is where I left it pending some input. I'm wondering if I should try condensers or what the most logical next step is.
At this point I will probably not invest a whole lot into it. After getting to this point I decided to give the merc a try to see if I could find the unknown issue with it. Had to rope wrap the flywheel as the recoil is shot. Damn thing fired up in 3 pulls and ran like a top despite not having run in over 3 years. The issue was immediately apparent as it was not pumping water. Pulled the bottom leg and found the impeller to be disintegrated. I'll be proceeding with this engine for now but trying to get the Johnson going as a spare if it can be done cheap enough.
After returning home I pulled the plugs and found one to look maybe a bit on the rich side while the other was still quite shiny and wet (#2 cylinder IIRC). I thought maybe I had lost compression so did another compression test, this time coming up with between 75-85# through my 3 attempts. Grounded the plugs and pulled it over with the lights out, both plugs look to spark ok. Pulled the flywheel and found #1 points to be around .025 and #2 to be .020. Both sets of points look ok, so I set #1 to .020, and that is where I left it pending some input. I'm wondering if I should try condensers or what the most logical next step is.
At this point I will probably not invest a whole lot into it. After getting to this point I decided to give the merc a try to see if I could find the unknown issue with it. Had to rope wrap the flywheel as the recoil is shot. Damn thing fired up in 3 pulls and ran like a top despite not having run in over 3 years. The issue was immediately apparent as it was not pumping water. Pulled the bottom leg and found the impeller to be disintegrated. I'll be proceeding with this engine for now but trying to get the Johnson going as a spare if it can be done cheap enough.
