1997 GTX Runs bad once it warms up!

[teebee]

1997 GTX carbs have been rebuilt factory kit, top engine has been done, cold & warm compression good, new coil, spark plugs, rebuilt rave valves and water regulator, runs great when it’s cold soon as it warms up 15 minutes Or so, it’s starts bogged down backfiring, it feels like it’s running on one cylinder, I swapped the carburetors off my other 97 GTX same problem, I’m thinking rectifier or Trigger Coil in the magneto. I can’t get the problem to occur out of the water. Any help would be appreciated
Thanks

 

[Lothsahn]

Check your rectifier. Disconnect the red wire from the rectifier and see if the problem goes away. If it does, replace the rectifier.

note: With the red wire disconnected, your battery won't charge, so don't leave yourself stranded.

 

[teebee]

Ill try that for sure! The unfortunate part is I got to put her back in the water to test her, I wish there was a way to simulate a load on the trailer? so the rectifier could be charging but still cause my issue?
Thanks

 

[Lothsahn]

The job of the rectifier is to change the output power from the magneto coil into something that charges the battery. It takes very noisy, messy electrical input and makes it a stable voltage to charge the battery.

If the rectifier fails, it starts sending too much voltage into the battery, with a lot of electrical noise. This can cause the MPEM that controls the ignition and spark of the sea doo to stop working properly, causing the engine to miss and run very poorly. As the amount of power generated by the coil increases with engine RPM, the problem happens the most at high RPM's. That's why it will idle just fine but not go to high RPMs.

At least on my sea doo, the problem only occurred in the water due to the load on the drivetrain--out of water, it doesn't take much power to hit max RPM, so you could easily hit max RPM even with a bad rectifier.

You can test the rectifier out of water using a multimeter as shown in this video:

Warning: Don't run your sea doo at high RPM for long as you can overheat the engine and carbon ring. Even if you use a garden hose to cool the engine, you can still damage the carbon ring with high RPMs out of water. For me, I only had to do 2 quick revs of the engine to find that the rectifier had failed.