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My B20 has a 1994 Yamaha 200 hp 2-stroke. The motor starts to miss at higher rpms (above 3600 or so). If you run her at full throttle, she misses then completely falls apart until you throttle back. It oly does this under load and at higher rpms--she idles and runs at lower rpms fine (so far). I replaced the fuel/water separator (no water), and cleaned the little filter on the motor (almost no debris).

The local outboard guy (who I hear mixed things about) said that it sounded like a fuel problem, and said that because it only happened under load, he'd have to take a shot gun approach and replace the fuel lines and lift pumps (fuel pumps?) and rebuild the carbs.

I'd prefer not to go the shot gun route. I can't find any leaks in the fuel system. The hoses look fine. I guess I could put small in-line filters in the hoses from the fuel pumps to the carbs to see if they run dry. Any ideas or advice appreciated.

Thanks-

John

Edit- Fuel is always fresh. She only has a 30 gallon tank, so she gets fuel probably once a week if not more.

I think I got it. It looks like bad fuel pumps. Called the local guy again, and he gave a me way to check them and the pump didn't check out.

We like a cheap fix!

I have a Yamaha 130 on my dinghy and when the oil pump is not pumping enough oil the engine misfires and goes to about 1200 rpm. This is to keep from not having enough oil in the fuel. Check the pump from the oil tank to the engine.

I put her in tonight and she ran fine. Replaced both fuel pumps. Apparently, its a Yamaha thing and some guys replace them as maintenance every 3-5 years. Mine were older than that. Thanks.