Yamaha 200HP OX66 Fuel Pressure Drop

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I?ve recently replaced my (oldie but goodie) 1991 200HP Yamaha with a 2004 200HP OX66. The 2004 motor has only 50 hours on it and was previously on a friend?s 23? Sea Pro (with a transom motor bracket). We went for a test ride and the motor ran flawlessly. After the purchase I swapped the motor over to my 21? center console (mounted directly to the transom). The motor starts easily but when trying to bring the boat up on a plane the motor bogs down and sputters for fuel. I placed a gauge on the injector rail and noticed the pressure drop from 35 p.s.i. to 30 when this occurs. I have found with the motor tilted all the way down the problem is worse. When I tilt the motor up 10-15 degrees the boat will plane out & easily run at 3500-4000 RPM until I hit a wake & it will sputter again. I replaced the fuel bulb, hose & water separator to no avail. I have read many issues on this forum concerning the VST filter but this motor ran fine 3 weeks prior on a bigger boat, or does this sound more like a vapor lock (air bubble) problem. Any help would be greatly appreciated & just might save my marriage! Thanks.

 

[ARCHSEA BUNKER]

Re: Yamaha 200HP OX66 Fuel Pressure Drop

Take Off The Vst Tank Try To Save Gasket , Its $ 30 Remove Filter Soak Filter In Carb Cleaner , Blow It Clean With Air Hose , Do Not Damage It; Its $ 100 Part , Chances Are That In The Swap Over Setiment Lying In The Vst Tank Got Disturbed Hold The Gasket In Place With A Little Vasoline When Reasembling, If This Does Not Solve It Move To Low Pressur Fuel Pumps, Should Be Ghanged Every 3 Years $ 100 For The 3 YOU HAVE TO REMOVE MABEY 8 OR 9 SCREWS TO DROP THE BOTTOM OFF THE VST TANK , DRAIN THE TANK FIRST WITH THE SCREW ON THE BOTTOM.

 

[skinsfan1]

Re: Yamaha 200HP OX66 Fuel Pressure Drop

Archsea Bunker,
Thanks so much for the reply! I took your advice and pulled the VST tank today. The tank was clean with very liitle sediment but the VST filter screen had some crud built up on it. I soaked the filter in carb cleaner and blew it clean with a air hose. The VST gasket looked fine & I was able to reuse it. I also checked the canister filter (next to the VST) & it looked fine. I put it all back together and started it up in the driveway. I just got back from a test ride on the river and it runs like a new one!!! Thanks again for your help!