Need advice-2000 ox 66 yamaha

[alan campbell]

I have a 2000 Yamaha OX 66 225hp outboard and this is my problem. After running on plane with no problems for approx. 20-25 minutes the engine drops 800-1,000 rpms. If i stop, retart engine after sitting for 1 or 2 minutes the engine resumes running ok for a few minutes. The engine never totally stops running. My Yamaha man checked for codes and no code warnings appeared. This problem happens every time after running for approx. 20 minutes. Replaced CDI ignition (very expensive and dumb) and now they are thinking stator or ignition coils. The idea of just throwing more money at parts without knowing the problem is driving me crazy. Can anyone offer advice? I am not a tech but would love to pass on some valuable info on to my tech.

Thank you, Alan Campbell
acamp32962@bellsouth.net

[jb123]

fuel pressure test ?
clean test O2 sensor ?
check LP pumps
ohm out plug caps

[99yam40]

The Yamaha service manual gives tests and specs for the ignition system parts. Always test things to find a problem instead of just throwing parts at it and hoping it will fix it.
Find someone with the proper manual and the equipment to test properly.
Or get the stuff yourself and save even more money

[striperswiper12]

My first guess would be the fuel system.

That engine has a filter on the High pressure fuel pump that gets clogged from ethanol fuel seperation.

Go on THT and you can read all kinds of post about it.

I'd change the on board water seperator to a 2 micron filter and change it out every 200 gallons of fuel.

Next clean the VST filter and VST tank, easy work you can do yourself in less than 1 hour.

NOt sure if that year had mechanical low pressure fuel pump or an electric one.

If they are mechanical you have to change them every 2 years regardless of if they are bad of not. The diaphram inside the pump can crack causing raw fuel w/ no 2 cycle oil in it to enter the crankcase and seize your engine
The igniton system on those motors is great and very rarely fails the fuel system is the exact opposite so go there first. It's cheaper and faster.

[Dr1532]

Sounds like this motor is injected , clean your vst filter like mentioned, or better yet if you have not changed it in a while change it, a word of advice throw the o ring in ice asap or you will not get it to fit, it costs almost as much as the filter, a gd place to start