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75 hp mercury 4 stroke running rough

T

tracker

New member
" I have a 75 merc 4 stroke 20

" I have a 75 merc 4 stroke 2001. It has started to run very rough. I was told that probably the carbs were dirty or plugged. I removed the carbs and they are clean. Also checked the spark, firing on all 4 cyl's. Also installed new plugs. Now I am told that it could be a unbalanced condition in the vaccuum in the intake manifolds. I don't know what could have changed, the engine has about 50 hr's run time. Anyone have any ideas?
Thanks "
 
Tracker' If it is running

Tracker' If it is running rough at idle it could be a carb set up deal. Do you winterise your motor and how. It is possible that your progression ports may be plugged slightly or solid. Note; check your oil level to make sure it is proper. That could affect the motor. Also correct battery voltage is important. If the battery is weak the ECU may not function wright. One other thing' 2001 4 sroke motors have a problem with water in the crankcase oil. See a dealer for more info or reply back here OK
 
DJMERCMAN
Thanks for your re

DJMERCMAN
Thanks for your reply. I did take the motor to a authorized merc dealer and the tech. did find that the vaccuum was about as far off is it could be and still run. They used a digital tester and set the vaccuum on the carbs and bingo the situation cleared up. Runs like a top now. They told me that they have found a couple new motors right out of the box that needed adjusted. Hope this might help others that are having trouble.
Again thanx.
Tracker
 
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