Nfhtronnfh
New member
Just bought a 17' aluminum boat with a merc 50hp 4stroke (approx 1998) serial number 0G231450. Starts up great, seems to run well at full throttle. but in between idle and full it bogs down badly and kicks down to 2 cylinders. Did some quick checks of the motor when I got home.
Hooked up a timing light to each spark plug individually and watched the light for consistency. At idle It seemed erratic on 4 and 3. 1 and 2 seemed fast but consistent. Pulled each plug wire off individually and listened to hear the motor change or not. At an idle they all made the motor run noticeably worse when removed. When I reved it up till it began to bog and then number 1 and 2 both made no difference to how it ran when pulled. Leading me to believe there is an issue with the coils? Could this also be blown head gasket? Or a carburetor issue? Any insight or suggestions welcome. I also compression tested it when it was cold and didnt get good numbers. Though the 2 cylinders that tested the best were 1 and 2.... the cylinders that appear to be best. Does the motor need to be warm for proper compression test? Mine came up 90-80-80-70. I also noticed some milky oil on the airbox inlet.
Hooked up a timing light to each spark plug individually and watched the light for consistency. At idle It seemed erratic on 4 and 3. 1 and 2 seemed fast but consistent. Pulled each plug wire off individually and listened to hear the motor change or not. At an idle they all made the motor run noticeably worse when removed. When I reved it up till it began to bog and then number 1 and 2 both made no difference to how it ran when pulled. Leading me to believe there is an issue with the coils? Could this also be blown head gasket? Or a carburetor issue? Any insight or suggestions welcome. I also compression tested it when it was cold and didnt get good numbers. Though the 2 cylinders that tested the best were 1 and 2.... the cylinders that appear to be best. Does the motor need to be warm for proper compression test? Mine came up 90-80-80-70. I also noticed some milky oil on the airbox inlet.