Boat sat longer than usual over winter and now surges on take off and on pad. Boat is also 4mph slower. Plugs and fuel filters have been replaced o2 sensor has been cleaned. All fuel pumps replaced last year. Boat runs great when I add seafoam. Any suggestions on what to try next?
I had the same exact issue and found the filter on top of the VST was clogged. It's pretty easy to check and clean but it's kinda small. The part # is 65L-13905-00-00.
Thanks, I'll give it a try. All the shops are backed up for a month right now.
If the VST filter does not solve your problem like the other gentleman suggested, I would change the O2 sensor. I cleaned mine and bench checked it etc. and all seemed to be OK with it. However, motor still would drop RPM on the top end and then regain RPM. I wouldn't throw a $350 Yamaha sensor at it, but you can get the NGK / NTK 21006 sensor for $35 and an LS1 O2 sensor harness for about $16 and just mod it to use the NTK 21006 O2 sensor. From then on, changing the sensor is just plug and play and it's cheap enough that if it does not fix your problem you've only wasted $35...and if it doesn't fix your problem, you will have a spare sensor on hand for when you do need one.
Is there a part number for the Ls1 sensor harness?
I used this one https://www.amazon.com/gp/aw/d/B0140...b_b_asin_title
2006 Stratos 294 Pro XL.2005 Yamaha 200 VMAX 3.1L. 8" Hydro Dynamics Rapid Jack. Ultrex 112 I-Plot link. 2 Helix 10 Chirp Mega SI GPS G2N.
Update.
Replaced:
O2 Sensor
Plugs
Fuel Filter
VST Filter
Pressure Filter
LP Fuel Pumps
Fuel bulb
I have a small amount of oil in the breather/silencer. The boat will now reach WOT with the new O2 sensor but my hole shot struggles. If I make sure to turn the key to let the primer pump run it does better but there is still a slight surge. I'm thinking now the fuel/oil mixture is off or if there is a fuel pressure issue. If that's the case I'm not sure where to go from there. Open to ideas. Thanks
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