Thin Popping

[chrisbowers]

I have a 1985 Mariner 150 V6 That I think is thin popping. It was running great and then was out of action for about a month. Since then at idle it sorta "puffs" or "pops" at idle and is tough to start. When you open it up out on the water it runs fine. It also seems to idle better when it is out of the water and on a hose.<br /><br />I am thinking it could be one of the following:<br /><br />Bad fuel line/fuel filter<br />Bad Mix (not sure how to change this on the engine)<br />Bad spark plugs/wires (even though spark plugs were recently changed)<br />Gunk in the carb?<br /><br />Any help would be greatly appreciated!

 

[jim dozier]

Re: Thin Popping

You are describing a lean idle mixture circuit. 2-strokes "sneeze" when they run lean at idle. This also makes them hard to start. The idle mixture does not affect high speed running. The most likely cause is an incorrectly set idle mixture or a dirty carb or both. If enrichening the idle mixture screws 1/4 turn doesn't help, remove the carbs and do a complete cleaning/rebuild with a rebuild kit, carb cleaner, and compressed air. Go to the bottom of the page and buy a manual if you don't already have one.

 

[chrisbowers]

Re: Thin Popping

I'm pretty unfamiliar with this motor as I just got it recently. The screw you're talking about, is this the screw you turn 2 rotations for 30 seconds then back if you can't get the thing to start? I had to do that the last time I had it out. <br /><br />Why would it behave differently when its on the hose instead of in the water?

 

[The Marine Doctor]

Re: Thin Popping

http://www.themarinedoctor.com/fuelproblems.htm <br /><br />This will be of great help to you.<br /><br />As for not popping on the muffs. It does not require as much fuel as there is no back pressure on the exhaust.<br /><br />TMD

 

[chrisbowers]

Re: Thin Popping

Where do I adjust the idle circuit mix on this engine?<br /><br />Thanks

 

[jim dozier]

Re: Thin Popping

Every carb is different and I have no personal knowledge of that particular carb, thats where a repair manual comes in. It will have pictures and descriptions. In general, the idle mixture screw on a carb is on the front, or the left, or the right, or possibly the bottom. You may have to remove the airbox to get to it. Some meter air (unscrew lets more air in=more lean). Some meter fuel (unscrew lets more fuel in=more rich). Again, thats why you need a manual. Experienced mechanincs need a manual, so does everyone with less experience.

 

[Old Jarhead]

Re: Thin Popping

If it ran fine before the lay up I would think the carb setting is probably Okay. <br /><br />My "guess" is a carb cleaning would do the trick...