1988 Yamaha 99 fourstroke problem

"Ive got a 1988 Yamaha 9.9 4-s

"Ive got a 1988 Yamaha 9.9 4-stroke model # FT9.9ELG, that has what I think is a timing problem. The motor starts up great and idles perfect, but once you advance the throttle is surges fast like blup blup, blup blup, blup blup, blup blup. I hooked a timing light to the engine and you can see its not right. I just want to know how the ignition systems work on these things and how I can make sure the timing is ok. I know a ton about the old solid state ign. but nothing about this. I noticed there was a small magnet on the outside of the flywheel, and it passes by a tiny black box towards the front of the engine, does anyone know what this is? Dutch"

"The "alternator" on t

"The "alternator" on the Yamaha 9.9 is actually just made up of a couple of coils under the flywheel that generate AC into a rectifier assembly when a magnet in the flywheel passes by. It's a crude concept for charging, but it works."

"Forgot to mention; the timing

"Forgot to mention; the timing issue could be a number of issues - some of which might not actually be a timing issue per se.

To my limited knowledge, the motor is electronic ignition. I think. If so, then replacing that particular unrepairable unit might be the cure.

I did have a similar symptom, but it was actually related to water (condensation) in the fuel tanks. The Yamaha is notorious for not being able to handle the slightest amount of water in the fuel mix.

It's VERY difficult to stop condensation in the fuel tanks so I simply put a water separator (not really a fuel filter) inline on the fuel hose. It has a glass float bowl with a small drain screw at the bottom which allows the heavier-than-fuel water to be drained away. It worked for me.

Chris"