1988 merc 100hp - spark

[Amor]

at idle speed do all four spark plugs fire or only the top two. I know only the top two get fuel under 1800 RPM's, the bottom two kicking in over 1800.

 

[dilligafda]

Re: 1988 merc 100hp - spark

Yes all 4 cylinders have spark at all rpms. The 2+2 system works by taking fuel away from the bottom cylinders at low speed.