Shifter or Engine Issue ?

[Mrkoj]

Howdy all..Had the boat (23 ft Rinker Festiva) tuned up this year. It has a Yamaha 5.0 liter with a an OMC Outdrive. 225 hp at 4500 rpm. Was running fine first month of the season. A few trips ago, running it to 4k rpm caused it to hesitate above 3500 rpm..top end speed has slowed considerably over the last couple trips as well. Absolutely no issues under 3200 rpm, planes great, sounds great. Hesitation and " sputter "only when under high load 3500 rpm or higher.( only gets to about 35 mph )..in neutral I can easily increase RPMs to 5k without ANY issues and it sounds perfect. By the way I have also emptied the water fuel separator, so fuel doesn't seem like the problem. A friend mentioned it may be the shifter or shifter interupt ? Also - every other trip the shifter is tight, or incredibly loose, no rhyme or reason..any ideas ? Thanx !

 

[Maat222]

Re: Shifter or Engine Issue ?

They guy who did the tuneup should warranty it.
I should last a season at least.
The water separator still is not the fuel filter, so you could still have a fuel problem.
Don't see how it could be anything to do with the shifter.
Look for vacuum leaks, hoses that may have fallen off, cracked vacuum advance diaphram, etc.

 

[mkast]

Re: Shifter or Engine Issue ?

When was the last time the engine was tuned up?

 

[P 0 P E Y E]

Re: Shifter or Engine Issue ?

Most engines will rev to the sky in neutral with no load so that does not apply.

Many things can cause an engine not to turn up.

Since you say you have a shift leaver or throttle suddenly lose, suddenly tight symptom you may start by inspecting that system to see if it is working correctly.

I would look for loose or missing attach hardware on every part of the throttle and shift system. I would also inspect the actual throttle arm on the engine to see if it is going to full open position each time the throttle leaver is full forward.

Once I left a piece of hardware on my intake manifold. I think it was a pipe plug left over from an engine zinc change, any way it migrated to a spot that caused my throttle to only go to 3/4,.