Mike Cross
New member
Hi
I have a 2000 9.9 2 cycle. It's previously run absolutely fine but has now developed an annoying cough. It starts perfectly and when cold will cough at idle, it's a bit like a sneeze, running fine and then ah-choo! Once warm it seems to idle fine. However when in gear (forward or reverse) at idle it does it again. My guess is that when warm at idle RPM it's OK but when the revs drop slightly by being in gear the problem appears. Most of the time the motor continues to run but occasionally it will stop and needs a pull to restart. First thought was maybe a gummed up carb so I tried Sea Foam. Lots of smoke as advertised but no change in behavior. New plugs fitted - no difference. I took it to a dealer who said he couldn't find anything wrong which led me to suspect it might be fuel as he was using his fuel and his tank. So I put it back on the boat with fresh fuel, and for good measure, a new tank. No difference. I'm about to also replace the fuel line, however I'm pretty sure that will make no difference. My logic goes like this. It runs fine when opened up under load so it's not a problem caused by lack of fuel (e.g. an air leak or constriction in the line).
It's on a 25 foot sailboat and the danger is that as I'm approaching the dock I'll go into neutral ready to reverse and it'll cough and die at the worst moment. Anyone have any experience of this type of behavior and the cure?
I have a 2000 9.9 2 cycle. It's previously run absolutely fine but has now developed an annoying cough. It starts perfectly and when cold will cough at idle, it's a bit like a sneeze, running fine and then ah-choo! Once warm it seems to idle fine. However when in gear (forward or reverse) at idle it does it again. My guess is that when warm at idle RPM it's OK but when the revs drop slightly by being in gear the problem appears. Most of the time the motor continues to run but occasionally it will stop and needs a pull to restart. First thought was maybe a gummed up carb so I tried Sea Foam. Lots of smoke as advertised but no change in behavior. New plugs fitted - no difference. I took it to a dealer who said he couldn't find anything wrong which led me to suspect it might be fuel as he was using his fuel and his tank. So I put it back on the boat with fresh fuel, and for good measure, a new tank. No difference. I'm about to also replace the fuel line, however I'm pretty sure that will make no difference. My logic goes like this. It runs fine when opened up under load so it's not a problem caused by lack of fuel (e.g. an air leak or constriction in the line).
It's on a 25 foot sailboat and the danger is that as I'm approaching the dock I'll go into neutral ready to reverse and it'll cough and die at the worst moment. Anyone have any experience of this type of behavior and the cure?