Hello,
I have a relatively recent (2003?) Mercury 9.9 four stroke on a small hard-bottom inflatable. The engine will start up just fine (two or three pulls), but won't idle. At the lowest level of throttle that will allow the engine to keep running, the RPM will lope up and down from a low idle to high rev, just back and forth like that. If I try to reduce the throttle to an idle position, the engine will simply die. I can get it to smooth out, but at a higher throttle level, needless to say shifting into gear is interesting, as I can only do so at the higher throttle level. In addition, it can only achieve a plane if there is one person in the boat, Put any more weight in it and it just has no power even at WOT. I suspect it's a fueling issue such as a gummed up carb or something, but are there any other ideas? I've checked one of the spark plugs (it showed no abnormal condition) but I don't have a socket that will get the lower spark plug out. I'll be replacing the fuel filter, but it doesn't appear to be restricted.
Any clues? Thanks!
I have a relatively recent (2003?) Mercury 9.9 four stroke on a small hard-bottom inflatable. The engine will start up just fine (two or three pulls), but won't idle. At the lowest level of throttle that will allow the engine to keep running, the RPM will lope up and down from a low idle to high rev, just back and forth like that. If I try to reduce the throttle to an idle position, the engine will simply die. I can get it to smooth out, but at a higher throttle level, needless to say shifting into gear is interesting, as I can only do so at the higher throttle level. In addition, it can only achieve a plane if there is one person in the boat, Put any more weight in it and it just has no power even at WOT. I suspect it's a fueling issue such as a gummed up carb or something, but are there any other ideas? I've checked one of the spark plugs (it showed no abnormal condition) but I don't have a socket that will get the lower spark plug out. I'll be replacing the fuel filter, but it doesn't appear to be restricted.
Any clues? Thanks!