i Purchased a 1999 Johnson 9.9/15ho carb from a local marina in march. First two times out it ran flawless. Since then here is the issue. Upon starting with the RPM's high it runs great. As soon as i back down the throtle to idle to put it in gear it sputters and chokes out. It will do this repeatedly until i touch the idle adjust screw on the side of the carb. I took it back to the marina and of course being the day after i went out it ran fine. He did find a crack in the electric primer hose which then prompted me to replace all the fuel lines. Still no help. Over the 5 times i have had the boat out sitting a few weeks between outing each time i return to the lake i need to pop the hood and adjust the screw. This last time i had it out adjusted the screw was running fine, then later on while idling it sound as if it was missing or almost going to dead stop from idle 3 times in about a 5 minute interval. A friends brother said there may be varnish build up in the carb. What cleaner do you guys live by? Could it also be the needle valve i have to adjust every time?
Jay
Jay
