99 seadoo gtx RFI sputters at half throttle or less

[Tdietrich828]

Good evening everyone, i have a 1999 sead doo gtx RFI. The ski will run fine initially in the water for about 5-10 minutes then it will start to bog and sputter anything below half throttle. It will get worse the longer you ride. It will run fine on top end. It almost sounds like a rev limiter or a two step. After riding for 30 minutes it will not want to come out of the bog longer and longer even if you hold it wide open but will eventually come out. I have done spark plugs and cleaned fuel tank and new fuel pump and regulator with no improvement. Any advice would be appreciated!

 

[Grim]

Did you test and verify operation of the fuel pump and regulator? after install? Are they aftermarket or OEM parts

 

[Minton33]

Mine does the same thing between 3 and 4K rpm. It never gets and worse though, just stays consistent. Sounds like a rev limiter but a little more throttle and it pulls through it. I’ve checked all sensors, replaced fuel pump, checked injectors ect. Played with settings of raves and anything else that’s adjustable. Reset tps. Everything I could think of as well as other people. Nothing made any difference. I was told it was normal but I’m not sure I believe that. I wish you luck and would like to know what fixes it if you figure it out.

Good evening everyone, i have a 1999 sead doo gtx RFI. The ski will run fine initially in the water for about 5-10 minutes then it will start to bog and sputter anything below half throttle. It will get worse the longer you ride. It will run fine on top end. It almost sounds like a rev limiter or a two step. After riding for 30 minutes it will not want to come out of the bog longer and longer even if you hold it wide open but will eventually come out. I have done spark plugs and cleaned fuel tank and new fuel pump and regulator with no improvement. Any advice would be appreciated

 

[mikidymac]

All of the 787 engines have a slight miss sound when cruising around the 4000-4500 rpm range. It is something with the resonance in the tuned pipe just before the RAVE valves open. If that is the only issue and otherwise they run perfectly, that is just normal for the 787.

 

[Minton33]

All of the 787 engines have a slight miss sound when cruising around the 4000-4500 rpm range. It is something with the resonance in the tuned pipe just before the RAVE valves open. If that is the only issue and otherwise they run perfectly, that is just normal for the 787.

Mine starts at 3000 or less and goes to 4500 or so. It’s very very annoying and is not just a small thing. My 787 Challenger needs the carbs cleaned and runs in general poorly sputtering and shit from just off idle till the raves open and it is less disruptive than my rfi. It takes a fair bit of throttle to pull out of that rpm range and is effectively just a huge dead spot where it just sounds like a rev limiter in the throttle. But if I get into the throttle fast it goes straight through it perfectly. It’s only when maintaining those rpm’s or slowly going through them

 

[lavasioux]

All of the 787 engines have a slight miss sound when cruising around the 4000-4500 rpm range. It is something with the resonance in the tuned pipe just before the RAVE valves open. If that is the only issue and otherwise they run perfectly, that is just normal for the 787.

Cool!

 

[mikidymac]

Mine starts at 3000 or less and goes to 4500 or so. It’s very very annoying and is not just a small thing. My 787 Challenger needs the carbs cleaned and runs in general poorly sputtering and shit from just off idle till the raves open and it is less disruptive than my rfi. It takes a fair bit of throttle to pull out of that rpm range and is effectively just a huge dead spot where it just sounds like a rev limiter in the throttle. But if I get into the throttle fast it goes straight through it perfectly. It’s only when maintaining those rpm’s or slowly going through them

Continuing to run an engine with carb issues is a good way to ruin it. There is nothing on these that will fix themselves and just magickly get better.

 

[etemplet]

I had this problem with a RFI and it was the rev limiter inside the MPEM. Swapped MPEMs and the ski was fine. I kept the MPEM as a spare for testing. I've had other weird issues the RFI MPEMs. one energized the pto fuel injector so it acted like a jet blaster, the other caused a temperature increase on one of the electrical plugs and when I swapped it the plug ran cool and the ski ran just fine. Nice to have a stash of spare MPEMS.

 

[Minton33]

Continuing to run an engine with carb issues is a good way to ruin it. There is nothing on these that will fix themselves and just magickly get better.

I’m fully aware of this. I’m a full time mechanic at a Seadoo/can am dealer. I just haven’t had the time or care to do it. So used to dealing with the rfi I barely even notice it. Had much more pressing projects to do. It seems to be rich anyway as it will foul a plug if you let it do it too long

 

[Minton33]

I had this problem with a RFI and it was the rev limiter inside the MPEM. Swapped MPEMs and the ski was fine. I kept the MPEM as a spare for testing. I've had other weird issues the RFI MPEMs. one energized the pto fuel injector so it acted like a jet blaster, the other caused a temperature increase on one of the electrical plugs and when I swapped it the plug ran cool and the ski ran just fine. Nice to have a stash of spare MPEMS.

Good info. It’s also unfortunate as this is already a replacement mpem. Original lost spark and that was how it was when I purchased it. I Replaced mpem and it’s been like this every since so that would make sense

 

[etemplet]

Good info. It’s also unfortunate as this is already a replacement mpem. Original lost spark and that was how it was when I purchased it. I Replaced mpem and it’s been like this every since so that would make sense

Do your checks and rule out what you can. If need be maybe you could find someone nearby with the same ski and do a test swap.