1988 yamaha 9.9 four stroke help

[Dutch515]

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

 

[Dutch515]

Re: 1988 yamaha 9.9 four stroke help

anyone?

 

[sdsaw]

Re: 1988 yamaha 9.9 four stroke help

Dutch515,
Try changing your oil and make sure that the oil filter is clean.
That motor has a safety feature that if you have low oil pressure, the timing retards so you won't run it hard without oil pressure but it will start.

I had this happen to mine. Ended up having a corroded oil tank with exhaust and cooling water seeping into the oil tank.
Try the oil change and go from there.

Scott

 

[Dutch515]

Re: 1988 yamaha 9.9 four stroke help

Thanks sdsaw, I really hope thats it. It did run fine last year so keep your fingers crossed. Ill let you know how it goes. Dutch

 

[sdsaw]

Re: 1988 yamaha 9.9 four stroke help

Dutch let me know that changing his oil cured his problem.
With this motor, if the oil filter gets dirty, the oil pressure drops and the motor's timing will not advance -a safeguard to protect it from internal damage. It'll start but not run any higher than idle.

Scott

 

[Yamajoe]

Re: 1988 yamaha 9.9 four stroke help

The timing light should show the the flywheel timing mark in between the 2 marks beneath the flywheel, if the mark is out then you may need to check the pulsa coil, cdi unit, valve clearance, camshaft timing is out (slipped or strecthed timing belt) and or timing and valve train needs overhaul.