Logo
FULL SITE MENU

Coughing when idle. 1984 7.5hp

D

donaldboyer

Contributing Member
Mercury 7.5hp
2 cyl 2 stroke
1984
s/n 6613032
Very Good Condition

When I start and idle this motor, every few seconds it 'coughs'. OOccasionally stalls from this coughing but usually just loses a few revs.

Do I need to adjust the low speed jet on the carb? If so can you please post a pic of where this screw is as I don't want to turn the wrong thing!

Thanks!
 
Re: Coughing when idle. 7.5hp

Thanks, but I'd like to be sure I am turning the correct screw. Do you have a photo or pic from a manual please?
 
Re: Coughing when idle. 7.5hp

No, but it's pretty obvious. The one you want is slotted and located inside a deep hole at the front of the carb.

Jeff
 
Re: Coughing when idle. 7.5hp

Long time since I first asked about this, have only just got round to sorting this out!!

There doesn't seem to be a screw in a deep hole like you said. Is it the one circled in the attached pic??

CameraZOOM-20110123175436.jpg
 
Correct.---------------------Often if the carburetor throttle plate opens too soon you get what you describe.------------At idle the throttle plate ---------MUST BE CLOSED.
 
Oh ya, rub it in - was minus 24C here this morning. Let us know how you make out. If that doesn't cure the cough you could have a bad carb gasket or bad base gasket - either of those is also a common cause of a "cough or sneeze" (or maybe it's just summer cold) :)
 
Yeap, will do.

I'll try to post a couple of pics of where we go boating. Don't know about all you guys, but I find it real interesting to see where people boat in other countries!
 
Back
Top