Fuel Flow Issue?

Gulfstream C

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I have a 2002 Gulfstream with a Yamaha 225. I have taken the boat out 3 times this year. On the first 2 trips, the engine started up right away and ran fin at low idle. When I reached the end the no-wake zone at the end of my marina and opened the throttle up, the RPMs increased but the boat did not really respond and was very sluggish. Eventually she came up to speed, but each time during the trip that I went back to low idle and then tried to increase speed, I encountered the same hesiatncy. Last night, after changing the fuel / water separator filter, i went out again and experienced the same problem. Started up and ran at low idle fine, but when I opened the throttle, the engine stalled out and I was not able to get it started again, even after sqeezing the primer bulb. I would appreciate any thoughts / suggestions on how to address my problem. Possible bad gas? Air getting into the fuel lines?
 

wspitler

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If it is a fuel problem as it sounds, it could be the VST filter. I was told by a very knowledgeable Yamaha guy that a partially clogged VST will negatively effect higher RPM performance while idle may be OK. I saw it act like that on a friends engine.
 

seasick

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wspitler said:
If it is a fuel problem as it sounds, it could be the VST filter. I was told by a very knowledgeable Yamaha guy that a partially clogged VST will negatively effect higher RPM performance while idle may be OK. I saw it act like that on a friends engine.
This cause(clogged VST screen) is especially likely if the motor bogs or surges when hitting waves and bouncing.