Low RPM Spit

[Waco]

What would cause an engine to "spit" at low RPM? (every 5 seconds or so) When I say spit, I mean thats what it sounds like, and the engine hesitates for a second or so, then it picks up. It doesnt do it after you open the throttle a bit. Sometimes, if the engine is idling low enough, the "spit" will cause the engine to shut down.<br /><br />Fuel ratio? Idle air flow? Fuel pump?

 

[Yepblaze]

Re: Low RPM Spit

You might also refered to as a sneeze. Usually related to a lean idle condition.

 

[Waco]

Re: Low RPM Spit

This motor (9.9 Johnson), has a fuel ratio adjustment knob next to the choke. It seemed to do better when I turned it counterclockwise (sticker is gone, I believe that makes it leaner?) but as I turned it out, the motor did not seem to idle as good "between spits/sneezes" so I left it at about 1-1 3/4 out from seat. Does that sound right? ANything else that may cause this?

 

[Waco]

Re: Low RPM Spit

Could it have something to do with idle exhaust pressure?

 

[almost retired again]

Re: Low RPM Spit

Hello Waco;<br /> I'll agree with the above post I belive that it's a lean condition at idle. The knob your talking about is the low speed adjustment, turning it counter-clockwise will richen the mixture, and clock-wise leans it. When adjusting it you should have the boat in the water idleing in gear( not tied up) the adjust to the best idleing performance. No sneezing. If you have a hi seed adjustment it should be set first at WOT.<br />Hope this helps