F115 with no power

I am looking into buying an 18ft Customweld Viper with a 2008 F115. It is reported to only have approximately 70 hours on the engine. We put it in for a test drive and it started right up, idled and ran fine until we tried to open it up. It topped out at 4400rpm and then slowly back downed and settled in the 3600-3700rpm range at full throttle. It was never able to get the boat on plane. Boat had about 750lbs of passenger weight in it. It did not sound/run rough, just did not have any power. First opening at the Yamaha shop is 2+ weeks out. Would really like to get the boat, but not if it is going to take serious cash to get the motor running right. My plan at this point was to start with new fuel, new filters, new plugs. Any other suggestions?

Re: F115 with no power

What size prop?

Re: F115 with no power

Dropping RPMs to me means plugged up fuel system, and may be some internal ones not just the ones you can put you hands on easily. monitor fuel pressures to see what is going on

Re: F115 with no power

You can do this either of two ways. 1) insist the seller pay the tab (get that in writing) or 2) Offer a price that takes into account the estimated cost of repairs.

Re: F115 with no power

J...561: Prop is 13.25 x 17-k.

We are going through and changing all filters now. Found some dirt/grime at the fuel pump.