2004 Yamaha VMAX OX66 225 fuel filter question

[wcs69rat]

I have a 2004 225 OX66 that is / was not reaching peak rpm and if it did get up close to 5800 it would immediately roll back to approx 5300. It doesn't die or surge, it just pulls back and will not accelerate any more. I have it on a 93 19'3" Intimidator with approx 3" prop shaft to pad, turning a 25 pitch Trophy plus prop. I should be hitting the limiter with that set up at probably about 75mph. Instead I'm running about 66 at 5400. For a split second, I hit 70 at 5800 rpm and then it rolled back. It definitely seems like a fuel issue.....so.....low pressure pumps were changed a year ago and have maybe 10 hours on them. VST filter is spotless. New Yamaha OEM primer bulb. New fuel line from tank to engine main fuel filter. New Racor remote fuel filter. O2 sensor cleaned and voltage checks good. TPS sensor voltage set. New NGK Plugs. Spark verified at all cylinders. Replaced main eng fuel filter and filter bowl.

I am hopefully taking it out tomorrow to see if anything has improved...however...and I'm finally getting to the point of this post...when I was running it today with the hose hooked up to it, the main engine fuel filter bowl was full of fuel once i primed the bulb. However, once the engine ran for several seconds, air would appear in the filter bowl and the bowl would only remain approx 2/3 full of fuel. The engine never missed a beat but it seemed weird to me that the filter bowl did not remain full. As soon as I shut the motor down, the bowl would fill back up. Does anyone know if this is normal or has anyone else experienced this? I thought maybe it could be due to low rpm at idle and since the low pressure pumps work off of crank case pulses that maybe this is common until rpm increases....but I'm just guessing at this point. Thank you in advance for any input.

[javelin90]

Couple of things come to mind,
check and make sure the primer bulb arrow is in the correct orientation
did you replace the paper strainer filter inside the clear fuel bowl? If so is the rubber o-ring pushed up to the underside of the clear bowl filter?
I am guessing the air bubbles are an indicator that the fuel is restricted somewhere
The racor filter is the same flow rate as previous one used?

[wcs69rat]

I did verify the primer bulb direction. The boring on the filter housing is installed correctly as far as I know. I can double check it but I'm 99% sure its correct. I did replace the paper filter in the housing. I installed a 2 micron Racor filter instead of a 10 micron but it's still supposed to flow 60 gallons per hour and the motor only burns 30 at WOT. It also did the same thing with the old 10 micron filter.

[javelin90]

If you have access to a portable gas tank. I would suggest using that and see if issue is still pressent.

[CJ1]

REPLACE 02 sensor. Check and clean siphon tube. Cj