fastjeff
Gold Medal Contributor
Seen several postings lately of a similar nature: bad low idle to throttle up behavior, resulting in a bog or an outright stall. In most cases (assuming the timing and carb tip in is set correctly) the problem is idle mixture settings (usually too lean). Why is this happening, you might think, when the old dog always ran perfectly?
For one thing, time (and crud) makes a tiny hole smaller, so you need to open up the mixture screw a tad over time. Also, since ethanol is such a crappy fuel, adding 10 % to gas means you need to use more of the mixture to get the same power as before those boobs in Washington screwed up our gas.
Finally, there's "I don't have an accelerator pump" reality of outboard. Simply put, an auto engine would bog, backfire and die regardless of the idle settings if their carbs didn't have a squirter to add a bit of fuel when the throttle is moved. (Try running a car with a bum accelerator pump and you'll see what I mean.)
In the below video (towards the end) you can hear the result of a plugged. top carb idle circuit (the little #@^~!) I found this out after ripping the motor down in the winter, expecting to find the usual fired top piston (it's a Merc triple). As you listen to the video, note how it sounds like the motor is running out of gas (which, in essence, the top and middle cylinder were). If these carbs had an accelarator pump, the motor would have been just fine (though it stalled at idle. I was able to mess around with the enrichener and make it back in).
Jeff
http://www.youtube.com/user/57Fastjeff?blend=20&ob=5
For one thing, time (and crud) makes a tiny hole smaller, so you need to open up the mixture screw a tad over time. Also, since ethanol is such a crappy fuel, adding 10 % to gas means you need to use more of the mixture to get the same power as before those boobs in Washington screwed up our gas.
Finally, there's "I don't have an accelerator pump" reality of outboard. Simply put, an auto engine would bog, backfire and die regardless of the idle settings if their carbs didn't have a squirter to add a bit of fuel when the throttle is moved. (Try running a car with a bum accelerator pump and you'll see what I mean.)
In the below video (towards the end) you can hear the result of a plugged. top carb idle circuit (the little #@^~!) I found this out after ripping the motor down in the winter, expecting to find the usual fired top piston (it's a Merc triple). As you listen to the video, note how it sounds like the motor is running out of gas (which, in essence, the top and middle cylinder were). If these carbs had an accelarator pump, the motor would have been just fine (though it stalled at idle. I was able to mess around with the enrichener and make it back in).
Jeff
http://www.youtube.com/user/57Fastjeff?blend=20&ob=5
Last edited: