Just had my Donzi out for the second run since I purchased it. Seems a bit limp.
The 1st run I had just warmed it up and basically got it on plane to get the fluids moving before I changed them out. Nothing over 30 MPH. Started well, idled well, no overheat, good oil pressure. Not really impressed w the power, but wasn't really pushing the stick very hard.
The only issue was a leak in the Water pump / fuel pump housing. Since replaced w new.

As the boat had been sitting for years - I had a Merc mechanic check it over - pronounced it healthy.

2nd run was about the same with no leaks. BUT - no performance. Max 3800 RPM, and Max 50 MPH. Also the alarm that sounds off when you turn the key to ON, makes a very quiet buzzing after the engine starts. (not the full on alarm sound) Also Temp gauge occasionally jumps around a bit, but I can hold my hand on the risers - so not overheated. Also not the drive oil bottle signal. I disconnected those wires and it didn't change.

1995 502 MPI, Blackhawk Donzi low hours - stored for a few years.
31 props
Full fuel ( 94 Chevron)
New Cap , Rotor, and Plugs
New primary fuel pump
New belts
New Impeller


Spoke to another Blackhawk owner w stock 502 - he's at 78 MPH and runs the 31 props. So I assume stock engine pulls them OK.
He suggested possibly temp senders due to gauge jumping around ( might be 2 on this engine), the engine harness plug in (his had issues),
or timing. I don't see a spec on the engine info sticker for timing - it says to see the manual - is it even adjustable?

The fuel filter and fuel are new. Engine runs and starts great. Just seems "soft".
I guess a compression check, throttle opening check, maybe new plugs wires

Any ideas out there?

Thanks in advance!