Rough Running Motor

Farfromgroven

Recruit
Joined
Sep 29, 2020
Messages
2
I have a 1996 mercury force 120 hp ELPT OE183987. Runs rough below 2000 rpm. Have gone through carbs, cleaned out gas tank, replaced all gas lines and spark plugs. Compression #1 120 and the rest 130. Have to give full throttle to get started after floating around for awhile. I'm at about 7000ft what jet size is recommended? Help!
 

jerryjerry05

Supreme Mariner
Joined
May 7, 2008
Messages
17,923
What's the wide open throttle RPM's?
What's the RPM's in N??

Where are the air screws set?

Do a starting fluid test. Start motor and idle,
then spray starting fluid around the intake side
and under the pack and coils and around the fuel
pump and port covers.
If that makes a difference in the way it runs??
Then it's sucking air somewhere??
One backfire and it can blow a gasket on the
port covers and cause rough running.

Also once the motors running pinch off the fuel
line from the primer to the carb. Sometimes
the diaphragm in the primer goes bad and
excess fuel feed into the carb.
Check the reeds for broken, missing petals.
 

Farfromgroven

Recruit
Joined
Sep 29, 2020
Messages
2
Thanks for the help. will try this week end and ley you know the out come. Glad you people are here.
 
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