mercruiser 350 4bbl won't go above 4000 rpm,s

[lime4x4]

I have a 1986 mercruiser 260 hp 350 4bbl carbed engine. engine was rebuilt last year.complete tuneup done, carb rebuilt, ignition coil replaced.engine uses a electrical fuel pump.has thunderbolt ignition.currently running a 15 3/4 X 15 stainless steele 3 blade prop. If i floor it from a stand still the rpm's shoot up to 3200 rpm's and slowly climbs to 4000 as the boat starts to plane.Even if i trim the outdrive up to it's limit the rpm's stay at 4000 rpm's. my fuel flow meter is showing 15.65 gallons per hour flow the only i thing i take notice to is that my fuel flow is basically the same from around 2500 rpm's to 4000 rpm's. The engine doesn't sound like it starving for fuel

 

[Bondo]

Re: mercruiser 350 4bbl won't go above 4000 rpm,s

Ayuh,....

Somewhere around here, Don has a Check List of thngs to look at when WOT can't be achieved,...
Unforunately, I don't have it saved to share it with you,...
But,...
I'm sure someone will be along,+ know where to find it....

 

[cooter2506]

Re: mercruiser 350 4bbl won't go above 4000 rpm,s

Here is my Bible which I aquired from Don S

List of possible causes of low WOT.

Engine Won't Reach Operating RPM. Check

Fuel condition. Type and Octane possibly old fuel
Propeller pitch or diameter, damaged blades
Restricted fuel pickup tube or anti siphon valve Fuel System Test
Crankcase oil volume, high oil level can cause aerated oil and lifter collapse
Marine growth on hull and outdrive
Wrong gear ratio in outdrive
Restricted carburetor air intake (clogged flame arrestor)
Restricted exhaust system (broken exhaust shutters/flappers) in engine transom shield or drive
Poor cylinder compression Compression Test
Carburetor defective, or wrong type.
Fuel pump pressure and vacuum
Boat overloaded, improperly loaded, or improperly trimmed.
Engine Overheating
Engine timing and ignition system operation
Remote control cables and linkage for proper travel to open throttle plates fully.