SeaDooDoo90
Member
Hi guys - I recently purchased a '99 XP Ltd with the 951 in non-running condition. I am quite familiar with 2-stroke jet skis, though this is my first BRP ski and getting to know this one has been humbling.
The first thing I did was rebuild the carbs. I did not use a genuine Mikuni kit as I normally would have liked to, but instead went with this Venom brand on Amazon. They are close price-points, has good reviews and I believe it to be a high quality kit (many of the components were even made in the US). I was in a rush to get the ski running for a family reunion, and the factory Mikuni would not arrive in time so I purchased the Venom. In addition, I also replaced all of the factory fuel lines, which of course were rotten. When pulling apart the carbs, there was green sludge throughout and I'm confident this was a major factor to the ski's non-running condition.
After these two procedures, the ski started on the trailer and ran fine out of the water. Once in the water, it idles fine, but hesitates and bogs down slightly at accel. It's not a horrible bog, and easily overcome with a little bit of throttle feathering. Once above 3000 RPM, the ski runs quite well with zero hesitation or other issues, until it reaches about 5000 RPM, when the most glaring and problematic issue starts. The ski will run along at 5000+RPM for a few seconds, and all of a sudden drastically reduce RPM and fall on its face, then it recovers and revs up again to the previous RPM, then falls off again, and so on. It happens quickly and often - the entire cycle takes about 2-3 seconds to complete before it repeats. The bizarre part is for the first minute or two of riding, it runs above 5k RPM just fine. I've been able to reach almost 7k RPM and completed a ~2 mile loop around a small lake before the hesitation above 5k RPM starts.
I've read these fuel selector switches can go bad, and thought maybe it was causing a bottleneck in the fuel supply. I temporarily bypassed it and that did not fix my issue. I've also been experimenting with the carb's high and low speed screws. I know the factory specifies 1-1/2 turns out on the lows and 0 turns on the highs, but currently have the highs at about 1/8 turns out (with lows at factory spec).
Most recently, I noticed the mag-side carb's accelerator pump isn't working. With the airbox off (and engine off), I can see fuel squirt out of the PTO-side carb nipple, but not the mag-side. The carb rebuild kit unfortunately did not come with any parts for the accelerator pump so I'm unsure of its age.
My understanding was the accelerator pump only provided extra fuel upon an increase of the throttle, but that once a consistent throttle level was reached, it no longer did anything and fuel was only supplied by the normal high and low circuits. If this understanding is correct, a bad accelerator pump could explain the bog I experience accelerating from idle, but it does not explain the ski sputtering at a consistent 5k+ RPM, recovering, and repeating this viscous cycle.
What else should I be investigating for this issue?
The first thing I did was rebuild the carbs. I did not use a genuine Mikuni kit as I normally would have liked to, but instead went with this Venom brand on Amazon. They are close price-points, has good reviews and I believe it to be a high quality kit (many of the components were even made in the US). I was in a rush to get the ski running for a family reunion, and the factory Mikuni would not arrive in time so I purchased the Venom. In addition, I also replaced all of the factory fuel lines, which of course were rotten. When pulling apart the carbs, there was green sludge throughout and I'm confident this was a major factor to the ski's non-running condition.
After these two procedures, the ski started on the trailer and ran fine out of the water. Once in the water, it idles fine, but hesitates and bogs down slightly at accel. It's not a horrible bog, and easily overcome with a little bit of throttle feathering. Once above 3000 RPM, the ski runs quite well with zero hesitation or other issues, until it reaches about 5000 RPM, when the most glaring and problematic issue starts. The ski will run along at 5000+RPM for a few seconds, and all of a sudden drastically reduce RPM and fall on its face, then it recovers and revs up again to the previous RPM, then falls off again, and so on. It happens quickly and often - the entire cycle takes about 2-3 seconds to complete before it repeats. The bizarre part is for the first minute or two of riding, it runs above 5k RPM just fine. I've been able to reach almost 7k RPM and completed a ~2 mile loop around a small lake before the hesitation above 5k RPM starts.
I've read these fuel selector switches can go bad, and thought maybe it was causing a bottleneck in the fuel supply. I temporarily bypassed it and that did not fix my issue. I've also been experimenting with the carb's high and low speed screws. I know the factory specifies 1-1/2 turns out on the lows and 0 turns on the highs, but currently have the highs at about 1/8 turns out (with lows at factory spec).
Most recently, I noticed the mag-side carb's accelerator pump isn't working. With the airbox off (and engine off), I can see fuel squirt out of the PTO-side carb nipple, but not the mag-side. The carb rebuild kit unfortunately did not come with any parts for the accelerator pump so I'm unsure of its age.
My understanding was the accelerator pump only provided extra fuel upon an increase of the throttle, but that once a consistent throttle level was reached, it no longer did anything and fuel was only supplied by the normal high and low circuits. If this understanding is correct, a bad accelerator pump could explain the bog I experience accelerating from idle, but it does not explain the ski sputtering at a consistent 5k+ RPM, recovering, and repeating this viscous cycle.
What else should I be investigating for this issue?
