I purchased this motor new in 2009...it was packaged with a 2008 model boat. The motor ran great for the first year or so but since then has had problems with its fuel pumps. It's had its low pressure fuel pump (the pump that fills the vapor separator chamber) replaced twice before the latest problem.

The latest sequence of events: boat went in to have its 3-year/300 hour service done early, ran motor off of hose for roughly 10 minutes after service, boat ran great on the Intercostal about 2 weeks later, flushed motor off of hose for roughly 10 minutes after running it in Intercostal, then about a week later motor wouldn't even start. Apparently now the high pressure fuel pump is out. The pressure on one of the fuel rails was only 45psi and the other fuel rail was around 60psi...mechanic said they should both be around 90psi.

Does anyone know if this is going to be a common occurence now?

Oh yeah, I use Pennzoil Marine Premium Plus synthetic blend 2-stroke oil and have an external RaCOR fuel filter with see-thru bowl.

Any help is greatly appreciated.

yes those pumps do go bad , put pressure guage on it, did they clean the vst tank, air and fuel pressure should within 10 psi of each other, 90 and 100 psi. about your oil i had customer using other oil and engine wouln'nt even run for more than a second, use opti dfi oil only, look down the throttle plate to see if there is a large amount of oil pooling down there. the dfi oil is thinner than the others the thicker oil will not go thru thoil lines and backs up to the air pump and the return line from the air pumps dumps into intake area and that were all the piles up, then the engine tries to suck oil into and fouls out plugs. use dfi only

Actually the Fuel/air PSI should be 84/94 psi but you are right about the 10 PSI difference.
All Opti's puddle oil in the intake when they are tilted up regardless of oil because there is no fuel in the crankcase to flush it out but it will not foul the plugs from this.
Your difference of more than 10 PSI points to a failed Tracker Valve.
The fuel pumps are normally very dependable unless they
a) set with un-stabilized fuel in them and seize with Varnish (this doesn't sound like your problem)
b) there is air entering your fuel system via a hole in a fuel line, a bad seal or seat on your Racor, easily tested by installing a piece of clear hose where the boat fuel line connects to the motor. There should be NO air in it at all after the motor runs for 10 minutes or so.
c) you have too much vacuum on your fuel system, your mechanic can run a test on your boat while it is running at WOT in the water.
The tracker valve failure usually begins with symptoms of high RPMs on startup and erratic idle speeds.
As far as oil I run DFI oil in my Opti by choice but I have clients that run all kinds of crap and although I don't like it I don't think it causes a plug fouling issue I just question lubrication.