200 HP shutting down at full speed

[Thomas d]

I have a 1999 200HP fuel injection Yamaha that quits on me while running at full speed. I have bypassed the fuel tank and installed a 5 gal tank I have trying to eliminate tank problems and it does the same thing. When it quits it always cranks right back and idles great but will not accelerate. I have had problems with the engine loosing rpm's and cleaning the o2 sensor always seem to fix the problem not this time. Is there a way to determine if it is a fuel or fire problem. Today I replaced the diaphrams in all 3 pumps and still same thing. It seems to act like it is a fuel problem but I cannot tell for sure. Also should the fuel filter bowl be full at all times. When I pump the bulb it fills up but will not stay that way.Thanks. Tom

[flytact]

I think I may have enough knowledge to help on this one:
I think the remaining check is thet Vapor Separator Tank (VST) or Float chamber as Yamaha calls it. It is the tank on the port side of the engine. My filter leading to the high pressure pump was completely blocked. Relatively easy to clean but you will need a new $25 gasket.
To get inside the VST loosen as many screws as you can, then remove the three bolts to free the VST from the engine, loosen-remove the remaining screws and bolts. Then pull down on the tank. You should not need to remove any hoses.
Good luck.

[Thomas d]

Thanks a million. I did as you said and the filter was stopped up . I am cleaning it now and will let you know when I test it in the water. Thanks again. Tom

[Thomas d]

flytact
You are the man. This boat runs great. I cannot thank you enough. Tom

[Ken]

flytack,
Welcome to the forum and thanks for the help [img]smile.gif[/img] !


Tom,
If you don't already have one, you need to install a 10 micron water separating fuel filter in the fuel line just before the primer bulb.
Yamaha is now recommending this to counter the effects of ethanol blended fuel.

Good luck [img]smile.gif[/img] ,
Ken K