Re: Help on 1996-2000 OMC 9.9/15 HP FOUR Stroke

[Don]

OK, well first how do you know the lower crank seal is bad??
The ignition system is a strange one, you will see only one primary lead going to a dual fire coil. In other words, there is waste spark on both cylinders. This cost cutting measure led to engines that like to occasionally backfire during acceleration and some other bothersome running qualities. So, be sure you actually have an ignition problem before trying to diagnose engineered in headaches. Don’t have much experience with these engines, so I don’t remember if the flywheel has an "encoder ring" underneath to set timing, or if the flywheel magnets take care of timing.
Needless to say, start with the basics, such as stop switch elimination, connections, and ground tests.
Replacement parts for these are hard to find and expensive, fortunately you have another engine’s part to help with diagnosis…