Well I thought I scored a deal on a used 2019 Tohatsu 9.8 3V2 MFS9.8b kicker... the previous owner bought a used boat and it was the kicker. He had his "helper" try to run it and broke some parts off the carb while trying to clean it. Overall the motor looks like new, no corrosion really or even signs of use. Anyway, I bought a $40 cheap Amazon carb and put it on (yes I know paying $200 plus $50 shipping to Hawaii would probably be best but I don't want to get in too deep on the motor until I know it will actually run), along with new spark plugs (gapped properly), and changed the oil (making sure it's not overfilled... it's currently at 3/4) and it starts right up... but then after about 30-90 seconds starts running really rough and won't rev higher than about 1500 RPMs and you start hearing a knocking sound. Pumping the primer bulb doesn't help. Using a different fuel line and tank doesn't help. If I turn off the engine and wait it will run good again but then the same thing happens. I ran a compression test and with both plugs out it gets up to about 95 psi on each cylinder after 10 pulls. And then "wet" compression with a little motor oil in the spark plug hole gets about 115 psi. I checked the thermostat and it looked very clean and like new. My mechanic friend said that's too low compression and probably means there's internal damage causing low compression. I'm hoping it's something easier/simpler but I just don't know. I should probably buy the service manual but haven't had time just yet...
I would greatly appreciate any insights you might have.
Thanks in advance!
I would greatly appreciate any insights you might have.
Thanks in advance!
