1978 mercury model 200 skipping at idle

[wylie catter]

I'm still working out the kinks on this motor. It cranks good and runs great at higher rpms but it has a skip at idle. It is kind of a pop back through the exhaust. Or like a sneeze. Every couple of seconds when it's doing it bad. But sometimes it doesn't do it at all. Any advice is appreciated fellas.

Thanks in advance. Terry

 

[jerryjerry05]

Re: 1978 mercury model 200 skipping at idle

Start with a compression/spark test.Then rebuild the fuel pump.Check the gas for water.Clean the carb.Then reset the air screw.The engine warm and in gear,turn air screw in till it just bottoms out(gently)Then out till it smooths out and 1/2 more turn.Try these things.J

 

[wylie catter]

Re: 1978 mercury model 200 skipping at idle

Well, it has 120 on both cylinders. It has a new cdi box and plugs and great spark. The tank and all fuel lines are new and water free. I have taken the fuel pump apart to visually check it out. It looked alright so I put it back together without rebuilding it. But it might be a problem like you said. I have cleaned the carb. But I have not rebuilt it yet. I will try to adjust that air fuel screw and see if that helps.

Thanks, Terry

 

[mc66]

Re: 1978 mercury model 200 skipping at idle

The diaphrams in small carbs(fuel pumps) can not realy be determined good by the naked eye from what i understand.

 

[Maxz695]

Re: 1978 mercury model 200 skipping at idle

if in doubt change it out