225XL Mercury 4-stroke RPM drops after running @ full throttle

[edwardschnog]

Hi,<br /><br />I have had this strange experience with my 225XL Mercury 4-stroke, Serial# <br />OT750085.<br />When going at full throttle, which is 6000rpm the engine speed drops "all of a <br />sudden" back to 3000rpm. I wonder what's wrong, since my engine is brand new <br />(just a little over 20 hours). Immediately when the engine speed dropped I checked <br />the gasoline manual fuel pump (small rubber ball between fuel line, located just <br />before fuel line enters the engine) to see if it was soft (empty) or normal hard, but it <br />was perfectly hard. Also I noticed that there was no alarm sound, warning me that <br />something has gone wrong.<br /><br />I am not so happy with this engine anymore since I had to many things done with a <br />brand new engine. I had to replace a throttle cable bushing, as a recall. I have a <br />good amount of clearance in my trim system, causing the engine to tilt up approx.10 <br />degrees when reversing and then slamming down against the trim bracket when <br />slowing down again. I also have this strange noise which I hear at idle speed, it <br />sounds like a fan belt or a dry bushing. And now I have a problem which is causing <br />my engine speed to drop after going at full throttle for a couple of minutes (maybe 2 <br />min. or so).<br /><br />Can some one advice me what to do ??

 

[WillyBWright]

Re: 225XL Mercury 4-stroke RPM drops after running @ full throttle

Find an on-water Merc dealeship and have them take it for a ride. I assume it's still under warranty. Take advantage of that. Otherwise, you could jeopardize your warranty coverage. The main thing is to have them take it for a test ride. Some off-water dealerships have limited resources to properly test a boat under real-world conditions and that's a huge hurdle to overcome...leads to a lot of guess-work and misdiagnoses. If you can find one that also deals with Yamaha, that would be that much better since that motor is 100% Yamaha painted black.

 

[DJ]

Re: 225XL Mercury 4-stroke RPM drops after running @ full throttle

Edwardschnog,<br /><br />Your RPM drop issue sounds exactly like you are up against the rev limiter.<br /><br />The limiter will drop the RPM down to 3K until the throttle is pulled back. Once that is done, the computer resets itself.<br /><br />I don't think you want to be running that engine at 6K all the time. There are alot of parts flying around in there at that high rate of rev.<br /><br />It would be best to prop it so that it turns very close to its max RPM rating WITH A LIGHT LOAD. THat will get you best all around performance.<br /><br />I am finding that very few dealers have experience propping four strokes. The old 2-stroke rules don't always apply. The final gear ratios are sometimes quite different on a four stroke.

 

[BRIAN03]

Re: 225XL Mercury 4-stroke RPM drops after running @ full throttle

You need to run them that hard to make power. twist them to the moon. We need a special box to plug in them to shut off the rev limiter.

 

[Parrot6909]

Re: 225XL Mercury 4-stroke RPM drops after running @ full throttle

Just a thought......I had a similar issue with my 225 Optimax......throttle coil keeps blowing....check it out, my motor has 100 hours and 6 throttle coils in it...same description as yours....