90 hp johnson problems

mike8282

Cadet
Joined
Apr 27, 2010
Messages
16
my 86 90 hp johnson, lately my outboard has been shifting rough when trying to put into reverse. i dont know if this could be from low idling rpm's or if theres something else that is causeing it rough shift. most of the times the outboard will stall and ill have to restart. ive had problems trying to get the motor to idle perfect. ive rebuilt both carbs done all new fuel lines put in a new fuel pump. when i start the motor itll fire right up idle fine for awhile and then start to idle rough, poping every couple seconds like back firing. after awhile ill have to use the fast idle for a bit to get the motor to idle without stalling. i dont know if the throttle cables arent adjusted right or if it could be something else. im running new fuel/mix (50:1 ratio). the compression in all 4 cylinders is perfect. i did add seafoam to the fuel to burn out carbon build up, i dont know if this could be the reason of the rough idling or the carbs are misadjusted. if anyone has any answers they would be greatly appricated thank you.
 

waynehol

Petty Officer 3rd Class
Joined
Jun 4, 2009
Messages
88
Re: 90 hp johnson problems

Some folks more knowledgable than me will chime in , but my .02:

Im not sure about the adding seafoam to the fuel if it would cause the rough and popping. The symptoms sound like the engine timing may be way off. Do a link and sync and see if that helps.
 
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