motor not running at (W.O.T.)

G

grizzly600

Recruit
Joined
Jul 25, 2007
Messages
2
Hi, I have a 1981 mercruiser 3.0l 140 hp. I can't get it to run above 3200 rpm's at 31 to 32 mph. It has the right prop. It idles good and Jumps out of the hole great. W.O.T. rpm's should be about 4200-4800. It should run about 42-44 mph. I checked cam timing and points , plugs and everything else. I'm stuck , Can someone help me? Thanks,Tom S.
 
G

grizzly600

Recruit
Joined
Jul 25, 2007
Messages
2
Re: motor not running at (W.O.T.)

Hi, I have a 1981 mercruiser 3.0l 140 hp. I can't get it to run above 3200 rpm's at 31 to 32 mph. It has the right prop. It idles good and Jumps out of the hole great. W.O.T. rpm's should be about 4200-4800. It should run about 42-44 mph. I checked cam timing and points , plugs and everything else. I'm stuck , Can someone help me? Thanks,Tom S.
 
Haut Medoc

Haut Medoc

Supreme Mariner
Joined
Jun 29, 2004
Messages
10,645
Re: motor not running at (W.O.T.)


Welcome to iboats.....:)
Tom, I would do a compression check.....
I would also make sure all of my sparkplug wires are tight & good .....;)​
 
Don S

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: motor not running at (W.O.T.)

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.
 
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