FairbankFrank
Recruit
- Joined
- Jul 10, 2011
- Messages
- 2
I have a 40 HP Merc EFI 4 stroke bigfoot. the motor starts easily but idles rough and continues to idle rough. It almost sounds like one of the cylinders is not firing. how can I check spark without doing any damage? RPM at WOT is 4200, manual says it should be 5500 -6000