SX/SXi/SXi Pro '99 SXi Pro Won't Run Above Idle

jim_ii

jim_ii

Location
Michigan
My '99 SXi Pro has developed a problem where it won't run above idle in the water or on the trailer. It will run all day long at idle speeds, but as soon as I blip the throttle it dies. I've checked the in tank filters as well as the pulse line coming from the crankcase and all is well there. I've rebuilt both carbs with Mikuni kits (thinking maybe the fuel pump wasn't working) and that didn't help.

It's weird because this problem started 6 weeks or so ago. On that trip the ski started perfectly when we launched it but wouldn't run over idle. I rode it around the lake for 5 minutes or so at idle speeds and then everything was fine. On the next trip same thing. Almost like the fuel system needed to be "primed" before riding hard. This last trip it ran strong for an hour or so right off the trailer (no "priming" required) then started acting up again.

I started it on the trailer yesterday and it runs fine on the hose at idle. As soon as I give it any throttle it dies. I looked down inside the carbs and don't see any fuel entering the carb bores when I hit the throttle. Once it dies I can hit the choke and it fires right back up and runs fine at idle.

It almost seems like it gets enough fuel to run the low speed circuits in the carbs all day long, but at higher speeds it's fuel starved.

I've tried both the "on" and "reserve" positions on the fuel knob, no difference. The tank seems to hold pressure as I can hear the "whoosh" when I crack the cap after letting it idle. We ran 7 tanks of fuel through it a few weekends ago with no problems other than having to "prime" it first thing in the morning by idling around for a few minutes, so I don't believe there is water in the fuel. We used the same fuel in our 550 and it runs fine.

Engine is stock except for K&N filters and Boyensen Reeds. These were added 2 seasons ago and the machine has run fine ever since.

Could this be an electrical issue?

Anyone have any suggestions???

Thanks
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D-Roc

D-Roc

I forgot!
Location
Dirty River Rider
also disconnect the kill switch wires to make sure they are not shorting out when you rev it up. Yes it could be a bad coil, and i had an msd enhancer that would start and idle but would make the engine fart and blubber when you gave it gas.
 
SOCALSXI

SOCALSXI

Location
Rialto
I had something similar happen on my ski a few weeks ago and found one of my hoses was ripped. The hose would only open up when I rev it so I think once I got water inside it would squirt inside the carb or perhaps I would loose back pressure in the system. I am not a mechanic and not even sure if this makes any sense but I can tell you that once I fixed the hose, problem solved. The hose that was leaking was the main one coming from the exhaust and could not see it until I took it all apart. good luck
 
sxipro02

sxipro02

Location
Arnold MO.
98SXIPRO said:
try cutting the spark plug wires back 1/4"
Click to expand...

Im with this guy, I had some crazy running issues like this that was due to the wires. I had to cut almost a inch off the end before I found solid wire again, shocked it even ran.

Also check the basics like gaskets and hoses as others have mentioned. Loose carbs or leaking gaskets can cause wierd running issues as well.
 
98SXIPRO

98SXIPRO

One Of A K1nd
Location
The Bay Area
just a thought too, is it possible u have a faulty "hi temp water sensor"? causing the ski to go into limp mode....where it won't revv up like normal.
 
98SXIPRO

98SXIPRO

One Of A K1nd
Location
The Bay Area
i had an extra fitting tapped into my ADA head (4 outlets) and i ran a small fitting out of the head and into the temp sensor and then to its own dedicated pisser....never be to safe. lol. maybe with the new factory pipe ill delete it..
 
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