My son (13 years old) just bought a Boston whaler with the above motor on it. It had not been run for a couple of years so we had to dismantle and clean the carburetor. That got it going, but the main jet that sticks down into the float bowl was pretty corroded and gunked up. The thing I am calling the main jet is a brass tube that runs from the throat down to almost the bottom of the float bowl. The section that is in the float bowl has 3 holes drilled through it. The section that is in the throat also has three holes drilled in the side facing the intake manifold. The skinny tube that is inside this jet runs up to the top of the throat and connects to the idle circuit. On my Yamaha 9.9 the main jet unscrews, but on this Johnson it does not appear to unscrew. It is definitely in bad shape. Must have been sitting in water (or salt water) for a couple of years (thanks to the ethanol). We scraped away the gunk and blasted it with gumout. Also, after taking a 30 minute spin we looked at the carb and there was a small amount of gas collected in the bottom of the throat. Some had dripped out the front of the throat.
My conclusion is that the main jet is not doing such a good job of consistently creating the fine spray that motor needs to run steady and smooth because its tube body and the holes in it are rough and corroded and no longer shiney and smooth like when they are new. But I?ve never had a Johnson before so I am new to this carburetor and could be off the mark. I bought a carb rebuild kit with a new float, but it did not include a replacement for the main jet.
I?d like to replace that jet because it just does not run the way it should at wide open throttle. (revs seem to increase and decrease on its own, and if it is at half throttle and you go to full throttle quickly, it actually loses some revs for a few seconds and then gradually revs up to full throttle). However, it looked like the main jet was NOT one that could be unscrewed and replaced. In addition it had a small tube inside it that seemed to feed gas to the idle circuit. That tube was also pretty corroded. I don?t think this carburetor is going to last much longer.
I believe that the part number if OMC0439388 or 89
a few questions:
? Am I right that the main jet is the culprit?
? Is it possible to just replace the main jet? If so, what is the part number for the main jet?
? Does The whole carb need to be replaced?
Thanks.
My conclusion is that the main jet is not doing such a good job of consistently creating the fine spray that motor needs to run steady and smooth because its tube body and the holes in it are rough and corroded and no longer shiney and smooth like when they are new. But I?ve never had a Johnson before so I am new to this carburetor and could be off the mark. I bought a carb rebuild kit with a new float, but it did not include a replacement for the main jet.
I?d like to replace that jet because it just does not run the way it should at wide open throttle. (revs seem to increase and decrease on its own, and if it is at half throttle and you go to full throttle quickly, it actually loses some revs for a few seconds and then gradually revs up to full throttle). However, it looked like the main jet was NOT one that could be unscrewed and replaced. In addition it had a small tube inside it that seemed to feed gas to the idle circuit. That tube was also pretty corroded. I don?t think this carburetor is going to last much longer.
I believe that the part number if OMC0439388 or 89
a few questions:
? Am I right that the main jet is the culprit?
? Is it possible to just replace the main jet? If so, what is the part number for the main jet?
? Does The whole carb need to be replaced?
Thanks.
