almost new Mercury with rough idle

[wakelessinidaho]

Have a nearly new Mercury 20hp EFI 4-stroke outboard and it idles very rough and if left idling will completely shut off. At lower RPMs cruising it "misses" every so often. The lower the RPM the worse it works. Seems to work fine at higher RPMs.

Probably has less than 40 hours of runtime on it, mostly at trolling speeds. Super picky about keeping clean fuel and always use fresh non-ethanol gas.

Bought an expensive EFI 4-stroke so I wouldn't have this problem. Suggestions on troubleshooting? Is this fairly common?

Thanks folks.

 

[flyingscott]

If it's under warranty take it back.

 

[wakelessinidaho]

Well they are saying I have to take it into a local dealer and those guys find all kinds of stuff wrong that isn't "manufacturer defect" and then charge you for it. A lot per hour.

So I'm trying to troubleshoot as much as I can to make sure it's not something simple before I bring it in.

 

[flyingscott]

Nothing cheap about that motor. Needs software to diagnose.