Originally Posted by Dt125
............. 2000 rpm at WOT where as she used to do 2400. ........... I also replaced a section of fuel line with narrower pipe which may not be letting enough fuel through............
these boats have a reputation for fuel problems so I would get the right size pipe ASAP.
Assuming filters are ok it is worth air-lining the fuel lines back to the tank because at one time the Navy used a wooden dipstick and the result is that the tanks are often full of little slithers of wood
Other things to check are that all the fuel fittings are tight especially the ones from the lift pump onwards, these use a neoprene olive and I think they can become loose equally it is difficult to know how tight they should be
On the pump there is a pressure relief valve which holds pump body pressure at about 10 psi this will often block and is overlooked when servicing. If blocked this will knock 200-300 rpm of the engine but seams to have no other major effect.
This valve sticks out of the side of the pump and has a fuel return pipe on the other end.