Logo
FULL SITE MENU

mercury 8hp outboard spark plug not firing

1

14mclark

Member
hey, i've got an 8 horse mercury outboard, 2-storke, 2-cylinder, and it runs great, just got the carb cleaned and a new float valve in it. the problem is that the bottom spark plug doesn't fire, and therefore that cylinder isn't firing. because of this, it only goes half speed. i'm thinking that it is either the coil or the switchbox, what do you think? suggestions?
 
Switch the coils around and see what happens then.---------You say it runs " great "------------then you say " bottom cylinder is not firing " so what happened ???
 
What racer man means is, swtch the green wires going to the coils and see if the no spark situation follows to the other coil. If it does, the switch box is bad.

I suspect the coil. Seen many coils on those motors (7.5 to 9.8 hp) die for some reason. They have a different stator arrangement from the 20 hp and up, and it seems to eat the coils.

Jeff
 
You MGHT try swapping the trigger coil wires about and see what that does.

Jeff

PS: That particular spark box is hard to find on eBay (ie: used and cheap). It's also unique to the 7.5 to 9.8 hp Mercs.
 
Back
Top