- Location
- Ontario, Canada
I had a similar set of symptoms turn up with my ski over the last 2 months. The issues I had were a cylinder being dropped during low rpm's, turned out to be a coil showing signs of failing. Once I got past that, I still felt what seemed to be like the ski was hitting the rev limiter and carburetion was off. So I pulled the carbs, cleaned and found that water had made its way into the needle and seat area. Cleaned all that out, internal filters were good but did have a tiny bit of debris in them...if you have the stock fuel lines you may want to change them. After about 12-15 years of service they start to break down and plug the filters with what appears to be hair. This was a massive problem on the old 2-stroke BRP skis. One thing I tried to pay attention to in your descriptions was that the performance dropped off when the angle of approach changed. That would suggest to me that there is a fuel related problem going on there. If there is water anywhere in the system, like the fuel shut off valve or stock water separator has too much water in it, that water is changing position getting in the way of the fuel flow and cutting off any throughput.
One other area to look at, as weird as it sounds, is the one way valve on the tank vent. I just went through this over the last 2 weeks. It nagged me for months to change out my pump seal, that cured almost all remaining gremlins...that and the new coil lol. But what told me I had a tank vent issue was the hood liner. My hood liner had a white fog stuck to it right above the tank vent. I checked the vent, it tested out properly. I couldn't figure it out, I thought maybe it was backlog of too much fuel since the new pump seal changed everything and made the engine load properly, giving a rich running condition compared to how it was tuned before to the lesser engine load. I thought maybe the overloaded fuel charge was backfiring out the intake and sticking to my hood liner. So I cleaned the liner and went out, the ski ran pretty good but still not where it should have been. It would run amazingly for about 20-30 minutes then start losing power. Same thing as you, most noticeable when grabbing a handful of throttle to set up for an incline off of a big wave. I would get about 70% power and that was it. I get the ski back to the house, pull the hood and there is the fog again. It turned out to be a pin hole in the piece of fuel hose going from the tank vent spigot to the vent. I replaced the little piece of hose and haven't had an issue since. Hard to believe a pin hole on a vent line would be enough to mess with the running condition of a ski but it actually does...a pin hole darn it! lol. I checked everything, I mean everything. The tank vent spigot to see if maybe the tank was cracked around the spigot releasing pressure, changed the additional inline fuel filter, cleaned carbs, everything I could think of. It was just like your symptoms, felt like it guzzled a gallon of water. I figure that after 20 minutes or so of ride time, the fuel capacity is down enough that the tank pressure becomes needed to help maintain proper flow pressure. When it can escape like it did with my ski...even to the smallest detail, the pressure is too low and holding the engine back with insufficient fuel quantity.
A tip to help reduce water ingestion into the carbs, aim the breather tube so the opening is pointing toward the spark plugs. The stock breather tube when mounted according to the little lock-in tab aims the opening down toward the bottom of the fuel tank. That didn't seem right to me since when the ski is laying on its side from a spill and re-boarding, it probably has a good volume of water in the bilge too. The stock angle for the breather tube would make it act like a shovel and scoop water in since it puts the opening below the water line of a good and full bilge. Since I changed the angle on my breather tube I have had a substantial improvement in dry, water free carbs.
One other area to look at, as weird as it sounds, is the one way valve on the tank vent. I just went through this over the last 2 weeks. It nagged me for months to change out my pump seal, that cured almost all remaining gremlins...that and the new coil lol. But what told me I had a tank vent issue was the hood liner. My hood liner had a white fog stuck to it right above the tank vent. I checked the vent, it tested out properly. I couldn't figure it out, I thought maybe it was backlog of too much fuel since the new pump seal changed everything and made the engine load properly, giving a rich running condition compared to how it was tuned before to the lesser engine load. I thought maybe the overloaded fuel charge was backfiring out the intake and sticking to my hood liner. So I cleaned the liner and went out, the ski ran pretty good but still not where it should have been. It would run amazingly for about 20-30 minutes then start losing power. Same thing as you, most noticeable when grabbing a handful of throttle to set up for an incline off of a big wave. I would get about 70% power and that was it. I get the ski back to the house, pull the hood and there is the fog again. It turned out to be a pin hole in the piece of fuel hose going from the tank vent spigot to the vent. I replaced the little piece of hose and haven't had an issue since. Hard to believe a pin hole on a vent line would be enough to mess with the running condition of a ski but it actually does...a pin hole darn it! lol. I checked everything, I mean everything. The tank vent spigot to see if maybe the tank was cracked around the spigot releasing pressure, changed the additional inline fuel filter, cleaned carbs, everything I could think of. It was just like your symptoms, felt like it guzzled a gallon of water. I figure that after 20 minutes or so of ride time, the fuel capacity is down enough that the tank pressure becomes needed to help maintain proper flow pressure. When it can escape like it did with my ski...even to the smallest detail, the pressure is too low and holding the engine back with insufficient fuel quantity.
A tip to help reduce water ingestion into the carbs, aim the breather tube so the opening is pointing toward the spark plugs. The stock breather tube when mounted according to the little lock-in tab aims the opening down toward the bottom of the fuel tank. That didn't seem right to me since when the ski is laying on its side from a spill and re-boarding, it probably has a good volume of water in the bilge too. The stock angle for the breather tube would make it act like a shovel and scoop water in since it puts the opening below the water line of a good and full bilge. Since I changed the angle on my breather tube I have had a substantial improvement in dry, water free carbs.
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