70hp Johnson runs (rough) w/Cover off

[GeneOC]

While at low docking speed the engine started to run rough, and noticed the tank was almost out of fuel. Next day, w/new fuel, the motor ran rough at WOT with it automatically dropping to idle. Motor will now only run w/the cover off and then very roughly. The plugs are wet, but hooked up timing light and all 3 cyls getting spark. Took carbs down to float needle and seat only w/ no effect. Appears to be a rich fuel problem?<br /><br />Any suggestions would be appreciated.<br />Thanks in advance.<br />GeneOC

 

[almost retired again]

Re: 70hp Johnson runs (rough) w/Cover off

Hello Gene,<br />Two things come to mind, first are the floats parallel to the carb body when turned upside down? Second, is the timming linkage connected?<br />Keep us up-dated

 

[fireman 757]

Re: 70hp Johnson runs (rough) w/Cover off

Sounds like classic symptoms of an exhaust leak. Check where your engine connects to the lower unit and change this gasket. Fumes build up when the cover is on and engine runs out of oxygen.

 

[GeneOC]

Re: 70hp Johnson runs (rough) w/Cover off

Thanks gentlemen. I'll check both of your suggestions this Thursday (i'm taking the day off to work on this).<br />I'll post any findings.<br />Regards,<br />Gene

 

[GeneOC]

Re: 70hp Johnson runs (rough) w/Cover off

The problem is an exhaust leak. I pulled off the collar below the pan and found 3 bolts hanging loose. Normally these bolts attach the engine to the lower unit. 2 of the bolts had been broken off inside the motor.<br /><br />I brought the motor to a repair shop where it's currently in queue for fixing.<br /><br />Thanks very much for pointing me in the right direction.<br />Gene