Engine or Prop

I have a '01 20' Triton with a 2.5L 200 EFI, 25P Merc 3 blade prop. The engine in newly rebuilt, due to a ring hanging and breaking #5 piston. The boat has never had a good hole shot. The engine sometimes runs like a bandit, decent hole shot, then later in the day or after the engine gets warm, bad hole shot. The engine labors up to about 2900-3300 rpm then seems to hit the "power band". Once this rpm is reached, runs good. Can turn the Merc Prop at 5700-5800 rpm in hot weather. Engine makes great hp on dyno.

I've been told to put a Power Tech 25P 4 Blade Prop on it, which should cure the problem. Also told, the Merc 3 blades aren't the best on heavy 20' Bass Boats.

Is my problem an engine issue, fuel, or prop? Any suggestions would be greatly appreciated.

Re: Engine or Prop

You have an engine problem, Clay. Prop related problems do not come and go.

Sounds like you are running a cylinder down part of the time, probably the same cause that broke it before.

Many times engine "rebuilds" fix only the symptoms, not the cause.

Re: Engine or Prop

I was thinking the same... I've been through everything on that engine.. Fuel pump, Evap Canister Gasket/Filter, Reeds, Injectors, CDM's, TPI, and even tested the entire engine harness with a Ohm Meter. I even swapped the ECM/ECU with one from another engine and replaced a bad Ingition Control Module. The Diagnostic Computer shows everyting in proper operating ranges. (ie. Inj Pulse width, TPI, MAP, etc)

I've also read on the forums where others with EFI's of the same years (give or take a couple) are experiencing some of the issues.

I even spoke to a Merc tech (at Merc) who covered everything I've already done,, and he's stumped. (I wonder if Merc knows something they aren't telling)

I'm just wondering if the plugs on that engine are performing as they should. I did run into a plug problem, by having the incorrect plugs installed, because of a misprint in a Merc Manual. The engine wouldn't "load rev" over 2500 rpm, would just sputter and cut-out. I located a Merc update which designated the correct plug.