Is my engine too high? Rigged on a 30" gill bracket

[LIGlastron]

So my boat is a 23' Concord LS-7 outboard conversion on a 30" Stainless marine bracket. Engine is a Merc 250EFI with a trophy 2 4 blade 27 pitch prop.

I am having issues where the boat is cavitating on startups, very hard to plane out. Only getting 4900rpms out of the engine and you can tell the engine is WORKING to get the boat going. I measured the pad with a straight edge back to the engine and I'm seeing the anti-ventilation plate is 6" up from the bottom of the pad. So boat bottom is basically even with top hub edge of propeller. Seems way high?

Would this restrict my rpms by 6-800 or so? The only way to start off is to have the trim all the way down where the engine is almost tilted back. Full throttle is the only way to get going and it takes a while to get there, boat angle is very high and porpoises alot.

[XstreamVking]

Try a different, smaller pitch prop. A 27 seems about 3-4 '' of pitch too much. I would guess a 23p would be good. 5600 loaded and 5800 light is correct rpm's for a 3.0 250. And yes. You may be a little high. But I would change 1 thing at a time.

[LIGlastron]

Try a different, smaller pitch prop. A 27 seems about 3-4 '' of pitch too much. I would guess a 23p would be good. 5600 loaded and 5800 light is correct rpm's for a 3.0 250. And yes. You may be a little high. But I would change 1 thing at a time.

Well what's odd is I purchased a hydromotive intimidator 4 blade in 24 pitch, the boat won't rev past 2k with that prop. Called them and they told me to send it back to be drilled. Got the prop back and took it out and it still won't seem to spin it, it's almost like there is too much load.
After about 4-5 seconds the prop finally spins and revs up as if there is zero grip. Very odd

[XstreamVking]

Is the engine smoking like crazy? Have you pulled and inspected the plugs? Done a spark check? Done a scan for faults? You may have one or two coils dropping out and you are only running on 4-5 cyls. Or have an injector flooding out one.

[LIGlastron]

Only smokes a bit first start of the day, then seems normal. It almost seems as if it's a coil but I had it water tested with a tech and all seems to be in check with spark.

We removed the injectors and bench flow tested them, they looked straight across the board even. Good atomization.

The boat does seem to be burning alot of fuel to be honest. Could this be an ECM issue? It's a downdraft 250efi and it has a big delay in when the power kicks in. If I'm idling and put it in gear and put the throttle all the way it feels like there is a almost 2-3 second delay before the engine will rev up. Engine will rev to max RPMs if prop starts to slip and I let it rev up so I know the engine will reach peak rpm with some load however max I can achieve is 4900rpm and 46 mph which seems about 10-15 mph off for this hull

[XstreamVking]

Run history would tell a lot, if it is a sensor or elec component. Fuel is a little harder to diagnose. It will rev freely under a light load so that is not a real good power test. How about a compression test ? Should be 115 #s or better.

[LIGlastron]

Run history would tell a lot, if it is a sensor or elec component. Fuel is a little harder to diagnose. It will rev freely under a light load so that is not a real good power test. How about a compression test ? Should be 115 #s or better.

Engine has pretty low hours around 320 or so. Fuel pressure seems good weather at idle or at wot, compression was great all at 130.

fuel system seems good I even change the high pressure fuel pump thinking it was that. With the way the computer legs to give it gas it seems something definitely computer-related. I have a guy off the forum that's going to help me try his ECM

[SUNKIST]

CSFT. And l then leakdown. Compression, spark, fuel and timing. You ca see comp. With your guage, and the spark with 6 spark checkers from harbor f. and the fuel pressure with your guage. Hydro props are so touchy pvs wise. 3 blade merc like vking says. Fuel restriction...lines and filters. Is that a factory downdraft efi. Treat it like your old chevy 350. Ecms are usually the last resort for me.