9.5 Evinrude /Johnson is Missing/Coughing at idle

[treed67]

I have a 9.5 Evinrude that is around a 1970 model. It has a bad miss at idle. I have tried about everything I can think of. (Cleaned the carb, checked the valves, cleaned the crankcase breather valve, set the points......) Most people say to adjust the idle mixture, but that doesn't seem to get rid of it either. Could it be a coil, condenser, head gasket problem. It also seems to smooth out a little at idle if you hold the choke closed. Any help is greatly appreciated.<br /><br />Thanks.

 

[johnyrude]

Re: 9.5 Evinrude /Johnson is Missing/Coughing at idle

Treed67<br />There is a rubber seal around the lower shift shaft - looks like an acordian - that seals exhaust gases from being drawn up and into the carb on this engine. If your motor idles better with the cover off than on, this is prob. the cause. Problem is it is NLA but the part # is 309631. To check it out you have to drop the L/U and remove the plate in the exhaust housing where the shift rod goes up thru it.

 

[treed67]

Re: 9.5 Evinrude /Johnson is Missing/Coughing at idle

Haven't checked it yet, but if that is the problem, anyone have any ideas on a replacement substitute.

 

[almost retired again]

Re: 9.5 Evinrude /Johnson is Missing/Coughing at idle

Hey Treed, Are these problems present with the engine hood off? If they are then get a good insulated pair of pliers, or better yet a large fuse puller, and remove one plug wire at a time. If it changes RPMs when you pull it off or dies this means that cyl. is firing good; go to the next and try it. If both change RPMs then your problem is more than likely fuel related.<br />Let me know what happens

 

[treed67]

Re: 9.5 Evinrude /Johnson is Missing/Coughing at idle

Thanks for the info everyone. I think I figured out what it is. Anyone had experience with leaking crankcase halves. I noticed fuel running down to the lower unit, and started looking. When it coughs...its spitting out where the halves bolt together. I guess someone didn't do a good job sealing. Hope I can do better. Please give me any advice you have.<br /><br />Thanks