2002 dt 225

[Jbruneau3480]

Having an issue here for the last year and no one can seem to figure it out.
Engine starts and goes just fine.... as I am bringing the boat up to plane, and moving a bit i hit 5000RPM, as soon as I do that, BOOM it pulls itself to 4500 RPM and will stay there. Pull the boat down, start over and same thing happens.
I have replaced: high and both low fuel pressure pumps, all filters have been cleaned or replaced.
Had it out the other day to show one of my friends who is a bit more handy then me, felt exactly what it did and said it has to be something electrical telling the engine to pull the RPMS down.
im kind of out of places to look, anyone ever experience this? Have a fix? Suggestions?

[Solarman]

Are any warning lights turning on when this happens? Any warning codes? Does the motor surge when you get to 5000 rpms and then drop to 4500?
I might think the TPS (throttle positon sensor) could cause this, or if it surges as I mentioned above, then possibly the float needle valve and seat in the VST may be restricting fuel flow at full rpms?

Also, might check the fuel pressure regulator?

Good luck, post back on what you find out.

[Jbruneau3480]

No warning lights when this happens. No surge at all.
No codes as I am told this year 2 stroke doesnt have a code reader
Replaced fuel pressure regulator.

[Solarman]

Yes, your model will read some codes, usually on the Suzuki monitor guage. It will show up as a series of flashes of the check engine light.

The next thing I'd check is the gear counting coil, and the TPS (mentioned above), either of these two sensors could be breaking down at the higher rpms. The service manual has tests for both of these sensors, but the TPS requires a special plug-in pig tail to test properly.

The gear counting coil tells the computer the speed and positon of the flywheel, and the TPS gives the throttle positon. These 2 sensors plus the ECM (computer/ electronic control module) control the timing, signal to fire, with respect to speed, and throttle positon.

Just a thought, have you changed plugs, checked the plug wires for any problems? Often at higher rpms (WOT) weak plugs, or plug wires can break down, or arc to ground causing that cylinder to stop firing. If that is happening on one, or maybe two cylinders, it would probably drop you to 4500 rpms, just as you described?

Good luck, post back on what you find out.

[Solarman]

The more I think about your diagnosis, "what's happening", the more I think that you're losing 1-2 cylinders at higher rpms. Check the coils (both sides of each) by the book, plug wires, and plugs. I think you will find one, or two of these items causing all your problems.

Good luck, post back on what you find out.