Dropping Cylinder

traindrv · #1 (**permalink**) 09-12-2011, 12:26 PM

I have a 2006 90 HP Mercury 3 cylinder 2 stroke. When I go from idle to WOT it gets to about 4800 RPM it feels like it drops a cylinder and RPM's drop to around 4000. If I slowly open throttle to WOT about 80%-90% of the time it will run fine. I first thought had coil bad but not sure now, any ideas?

boats.net · #2 (**permalink**) 09-13-2011, 12:02 PM

Sounds like a fuel issue, is it fuel injected or carbureted?

traindrv · #3 (**permalink**) 09-13-2011, 10:50 PM

It is a carbureted 2 stroke.

traindrv · #4 (**permalink**) 09-13-2011, 11:10 PM

I figured if it was a fuel issue it would do it more consistant at full throttle.

boatmangc · #5 (**permalink**) 09-17-2011, 08:06 AM

Quote:

Originally Posted by traindrv

I figured if it was a fuel issue it would do it more consistant at full throttle.

Not necessarily, if a float level is a little low the related cylinder can surge.
If it is fuel it will damage the motor quickly, your fuel is also the source for lubrication in that motor.

traindrv · #6 (**permalink**) 09-18-2011, 08:19 PM

What is needed to do, tear all the carburators down?

boats.net · #7 (**permalink**) 09-20-2011, 11:45 AM

Yes the best way is to disassemble the carburetors, inspect/replace/adjust, clean and reinstall.

traindrv · #8 (**permalink**) 09-20-2011, 10:18 PM

Ok, I have already installed new fuel lines, a water seperator and have a new Mercury fuel filter ordered along with carbruator gaskets.

boats.net · #9 (**permalink**) 09-21-2011, 09:31 AM

If the problem persists then start testing the ignition system, start with the coils.