Diminished Rpms

[Gene Regan]

   
Hello Everyone,
Recently i was motoring and realized that my rpm range seemed diminished . I was in the past able to get as much as 3000 rpms when needed. Now I only top out at 26-2800 . This is when I am in gear going forward. In neutral I can rev to 3400. Checked prop and shaft for fouling and nothing found. Stuff box is normal drip, Shaft turns freely when moving forward in neutral. Trans fliud is up to snuff. Throttle linkage still seems to be in same location as it related to the stop mounted on the engine. Cant seem to put my finger on it so I pose it to you all. Please advise .

[fairwinds]

capiton,
I would suspect bottom fouling, assuming that your linkage is ok! But you know what assuming can do.
Jeff

[SteveLyle]

Limited fuel flow - is your pump working?

Is your top speed lower - if it's the same, maybe the problem is your tach.

[Stu Jackson]

Could also be the throttle friction under the compass in the binnacle.

[Ray & Sandy Erps]

With diminished RPM's under load, I would suspect limited fuel flow as well and would confirm that the fuel transfer pump is working and then change the primary fuel filter.  Also, there's that screen in the fuel tank pickup line that has been talked about quite a bit.

If those items are okay, I'd look at the exhaust smoke for clues while underway.  Dark smoke may indicate restricted air intake (not likely) or restricted exhaust outlet such as a carboned up exhaust manifold, which can also restrict RPM's under load.  

Those are some of the more likely causes need to be checked before futher troubleshooting.

[Gene Regan]

   
Hello Again ,
  Well problem solved. It was the throttle cable assy coming out of its retaining bracket . The bracket is on the side of the engine and it s visability was obscured by some hoses which I rerouted today. The discovery was made by my son Matt. Thank God for youth and good eyes. Thanks to everyone who replied.

[Mike and Theresa Vaccaro]

Good point, Gene.  On the M-25XP, the throttle cable end is held in place with a clever "flip" latch.  Makes it very easy to change the cable, but it can pop open.  The clutch cable is secured with a bracket and two #10 screws.  Both should be checked occasionally, and the throttle cable retainer is visible when you check your oil.  If the cable becomes disconnected, you just need to pop it back into place and secure the lever.  

Cheers,

Mike