Jupiter Dinghy
Regular Contributor
I have recently purchased the motor listed above, and after replacing a bad water pump, went for a test ride, where the motor was not really running smooth (bit of a sputter at times) and could not manage to plane my 9.6' inflatable dinghy.
So I went home, replaced the prop with a 9.1/2 - 10 which is much more appropriate than whatever was on it and didn't seem to move much water, and also pulled the flywheel and set the points timing (which was way off).
Go back to the water, motor runs like a champ and planes my dinghy as it should, but after each run at full throttle, when I get back to slow or idle speed, I get the sputtering again, I reopen the throttle for a second or so, motor jumps right back up in RPM and sputtering stops even when back to idle speed.
Then I get home and put the thing in test tank for a good flush and here is what happened:
Motor started (after a few cranking attempts) runs ok for about 20 seconds, and then dies as if starved of gas.
I check the bulb and make sure it's pumped hard, can see the gas flowing in the line from the pump to the carb so I know there is gas in the carb, and start it again. Same thing. Start it again, same thing, did this about 5 times pumping gas to make sure it wasn't a gas feed issue, motor keeps dying after 20 to 30 seconds of running.
I read a lot about these old 9.9, and I understand they can be tough on spark plugs, points and condensers...
Any ideas where I should look first? Thanks!
So I went home, replaced the prop with a 9.1/2 - 10 which is much more appropriate than whatever was on it and didn't seem to move much water, and also pulled the flywheel and set the points timing (which was way off).
Go back to the water, motor runs like a champ and planes my dinghy as it should, but after each run at full throttle, when I get back to slow or idle speed, I get the sputtering again, I reopen the throttle for a second or so, motor jumps right back up in RPM and sputtering stops even when back to idle speed.
Then I get home and put the thing in test tank for a good flush and here is what happened:
Motor started (after a few cranking attempts) runs ok for about 20 seconds, and then dies as if starved of gas.
I check the bulb and make sure it's pumped hard, can see the gas flowing in the line from the pump to the carb so I know there is gas in the carb, and start it again. Same thing. Start it again, same thing, did this about 5 times pumping gas to make sure it wasn't a gas feed issue, motor keeps dying after 20 to 30 seconds of running.
I read a lot about these old 9.9, and I understand they can be tough on spark plugs, points and condensers...
Any ideas where I should look first? Thanks!
