[sportcraft17]

Hi, I have a 1996 Mercury, 5 hp one cylinder, compression is 90 Psi, spark is good and fuel on carburetor, but motor won't start, after priming the carburetor, on the second pull it will make one loud explosion and that's about it after that you can pull all you want and nothing happens, it will make the explosion always on the second pull, can this be related to the spark plug? I got like that, so I don’t know what they did before… any idea what is the spark plug Champion part Number for this outboard? I will really appreciated any help

Thank you

[WillyBWright]

My Champion book is too old, but going by the cross reference chart, the parts catalog shows a NGK BP7HS-10 which would cross to a L78YC4. It sounds like a timing problem. That could be casued by a sheared flywheel key or loose magnets in the flywheel.

[JB]

My bet is on a sheared flywheel key.