Need some advice

[chouser5]

Last July I bought a 2001 Crownline 205 br it has a new long block and when I took it out first time was still in the break in period after finishing the break in I was happy to finally open her up but to my dismay the boat had a really hard time getting on plane and would only run up to about 3100 rpms at wot so at the time I didn't know it should run at 4400 to 4800 at wot. It came with a 21 aluminum 3 blade so I thought if I went to a 19p 4 blade it would fix my problem well I was wrong. Still have the same problem today and since then I have found out that I needed new plugs and wires so changed them still no better I have the mecruiser 5.0 efi aND the boat weighs 3500 lbs dry. Now I am back to thinking that the prop pitch is too high the boat runs smooth as silk but takes an eternity to get on plane and then at wot still 3100 rpms and barely 30 mph trimmed out I am so frustrated any suggestions would be much appreciated

 

[chouser5]

I am wondering if I still have a power issue or it is just over propped as everything I have read suggest that a 17 p prop is the right application I have been throwing money at it with no results help please

 

[steelespike]

I suspect a motor problem. We need your prop size year and hp of the original motor or the gear ratio.
Do a light load wot run and get the rpm and gps speed.
I figure wot with a 21" prop should be around 50.
Don't assume because its a new block that everything is right.Cam timing,throttle linkage 2 plug wires transposed
Fuel pressure low. Is there a base timing setting?Back to basics.

 

[chouser5]

The motor is a 5.0 efi with a 1.62 gear ratio and the boat is a 2001 Crownline br I have changed plugs and wires and had the timing checked but I am not sure if the guy I bought it from was running the right size prop it had a 14.25 ? 21p on it when I bought it and it would not plane very well so I I got a 14.18? 19p 4 blade stainless thinking it would help but it didn't 3200 rpms is the best I can get almost 1200 off of mfr spec for my motor

 

[steelespike]

The 21" prop should get you right around 50. Is the bottom clean and smooth?No bulges or hollows in the bottom.
Does it respond to up trim?Have you confirmed the plug wires are on correctly.If 2 wires were crossed it would make you a 6 cylinder dragging 2 dead and 30 mph
does make you wonder.The other day we had a new Merc 115 4 stroke with a bad coil.Was running on 7 cylinders.
Does the throttle open all the way?Not the handle the throttle body.Don't assume everything is right. Do a compression check,Do a drop cylinder test.
If the motor checks out confirm the gear ratio.Confirm the base timing and does the timing advance as it should.