1986 Yamaha 90 hp 2 stroke ETLJ running rich and new spark plugs not looking good

Blue Man

Cadet
Joined
Jan 22, 2015
Messages
24
[h=1]I got my engine running better tonight (although not under load so I don't know for sure yet). However, it seemed to be burning really rich because we could smell gas in the exhaust and our eyes were burning after 5 minutes. I pulled the (almost brand new) spark plugs after running the gas out of the motor and they didn't look so good. (Please see attached photo).

I looked through the service manual and couldn't find how to make adjustments to stop the motor from running rich. Here's what I've done recently related to the fuel system:

Replaced fuel pump
Replaced fuel filter
Replaced fuel lines
Cleaned the carbs and looked at the floats (float mechs seemed good so I didn't replace them)

Any suggestions?[/h]
 

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alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,581
[h=1]I got my engine running better tonight (although not under load so I don't know for sure yet). However, it seemed to be burning really rich because we could smell gas in the exhaust and our eyes were burning after 5 minutes. I pulled the (almost brand new) spark plugs after running the gas out of the motor and they didn't look so good. (Please see attached photo).

I looked through the service manual and couldn't find how to make adjustments to stop the motor from running rich. Here's what I've done recently related to the fuel system:
fetch

Replaced fuel pump
Replaced fuel filter
Replaced fuel lines
Cleaned the carbs and looked at the floats (float mechs seemed good so I didn't replace them)

Any suggestions?[/h]

How is the compression?
 

robert graham

Admiral
Joined
Apr 16, 2009
Messages
6,908
Is your red Primestart lever in the correct "normal" position?....if it was in the "on/open" position might cause rich mixture......Maybe double check that newer fuel pump for a bad diaphragm?
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,589
Pull airbox and look in throats of carb and you will likely see fuel dribbling from emulsion tubes. This is either needle and seats worn or floats are heavy...
 
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