merc 120 I/O running pig rich when cold

ruggles

Petty Officer 2nd Class
Joined
Jul 30, 2008
Messages
110
It's especially bad when it's first cold and runs like ish and will stall out if I don't warm it up before going anywhere. The black smoke is so bad that the water coming out the exhuast is sometimes black and I can smell the fuel big time. Any ideas? I am new to I/O's. Could it be a malfuctioning choke? Carb toast? It seems to idle a lot better once it warms up but still bogs if you hammer the throttle. Any ideas of where to begin would be much appreciated.

The motor is in 1976 Glastron v-174.
 

ziggy

Admiral
Joined
Jun 30, 2004
Messages
7,473
Re: merc 120 I/O running pig rich when cold

sounds carb related to me.... have ya done anything to it. like a minor tuneup. that needs to be done too. but black smoke would lead me to the carb too. i get a black smoke ring around my boat, from running to rich too i think. i just rebuilt my carb today... no sea trial yet, so don't know if it cured my problem or not... have ya got yer service manual yet? yer gonna need one of them.....

http://forums.iboats.com/showthread.php?t=251571

#2 looks like it'd suit ya well.... even has a trouble shooting guide in it for hard starting, carb related......
 

ruggles

Petty Officer 2nd Class
Joined
Jul 30, 2008
Messages
110
Re: merc 120 I/O running pig rich when cold

hey thanks for the info and the link! I am downloading the manual right now:)
 

Uraijit

Banned
Joined
Feb 5, 2008
Messages
884
Re: merc 120 I/O running pig rich when cold

hey thanks for the info and the link! I am downloading the manual right now:)

Might as well have a seat, at 1111MB, this could take a min. :D Hope you're not on Dial-up...
 
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