low rpm at WOT

[MJVAUGHANS]

I have a mercruiser 140 with an alpha one drive on it. It is in a 1984 or so searay v-hull. When I run it out on the water it will not get above more than about 2500 rpm wot. I just put new plugs, plug wires, dist. cap and rotor on it. It starts easy and idles fine. When I try to hole shot it just winds up smoothly and when it gets to about 2500 rpm it just tops out. I can give it more throttle but it just does not climb any higher. Where do I start?

 

[Don S]

Re: low rpm at WOT

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 (Full tuneup done recently)
• Remote control cables and linkage for proper travel to open throttle plates fully.
• Check tach for accuracy