Super Jet Some input please...

[Air Biscuit]

So just looking for some input here/opinions here. Last time I rode the ski it all of a sudden started running funny, hesitating. Round nose SJ w all the staple mods, limited set up. I went in because it was about time to wrap the day up anyway. Once i checked it just seemed as if I was on the threshold of having to switch to reserve so I thought possible just sucking air, I chalked it up to that. The ski sat for 2 weeks. I put fresh plugs in, not that I think this has anything to do with any of this, just a side note. Went to ride today for the first time since. Fuel topped off, fired the ski on the hitch hauler and it fired but noticed it idled alittle erratically, not really too bad but enough out of the ordinary to catch my attention. I bliped the throttle a few times. The ski started to run away. But it didn't just take off. I've had a ski run away on my and it was not like that. This seemed like it revered up and held at a midrange rpm but certainly not wide open. Maybe it just didn't get the yet though. I held the throttle open and got it to stop. Checked over for any obvious air leaks like pulse line, fuel line cracks, loose carbs, etc. everything seemed happy. I tried again and it seemed to be idling fine. Bliped the throttle everything seemed normal. So I figured put it in the water. The hesitation was still there from last time. Just off idle then it opens up normally. I rode it around for only a min or two. Back on the hauler seems to be idling fine again with out running away.
So basically my question is would it take air in the fuel lines take that long to works its way out or should I get to leak checking the motor? This ski has run flawlessly since like 2010 or 2011 when I first did all the mods. Thanks for any input.

 

[Tyler Zane]

A crankcase airleak doesnt just come and go. Ive seen 3 skis run away from a crankcase leak and they all shot straight to the sky.
You may know this but ill say it anyways. If it does runaway, hold the stop button and hold the throttle wide open.
Your fuel lines should stay primed, if not then the fuel pump is leaking. With that being said, its probably time to do a carb job if the last time was in 2011 when you did all the mods. You can put a clear piece of hose inline right before the carbs to watch for air bubbles too. You may be pulling air in your fuel lines.

Do yourself a favor before you dig to much and check compression, and spark. Always start at the basics.

 

[chevota84]

Mine has been idling high erratically and I can see air bubbles in the inlet line sometimes. I'm going to try new fuel lines and I'm going to isolate the primer to its own circuit, it was fine last year and the only thing I changed was the primer.

Sent from my SM-G930V using Tapatalk

 

[Tyler Zane]

Primers are notorious for causing airleaks in fuel systems. You can put the primer on the return line. I loop the return line about five times into a tight spool and pull the primer from one of the center loops. I just zip tie it up neat now i never have to worry about a primer causing an air leak.

 

[chevota84]

I have a triple pickup and I'm only using one so I'm just going to plumb it into one of the extras and totally isolate it.

Sent from my SM-G930V using Tapatalk

 

[Air Biscuit]

Compression is good 175 in each cylinder, I checked that for the hell of it when I changed the plugs out. Spark wise I did notice the rear cylinder boot had alittle black arcing inside the boot. Prob should put new ends on. The more I think about it I'm leaning towards air in the fuel from being low, idk. I'm going to let it run on the hose for a while, see if it works its self out. The run time with the issue has not been long at all so it still may have air. If it seems better, then try it on the water one more time before I get to crazy. If not I'll try replacing my lines. To rule out any leaks. They're the original lines and the ski is a 2000 so can't hurt. Maybe rebuild the carbs again too. Thanks for the responses

I should also note the ski has no choke, or primer on it. It always cranks and fires. If it sits for an extended period of time like over a month it will crank for maybe 8-10 seconds and fire no problem. Always ran it like this since I did the mods 5+ years now.

 

[Tyler Zane]

If there was a little air in the fuel system it shouldnt take long to get worked out. Maybe 30 se to a min tops. Your fuel pump is cycling fuel much faster than your engine uses it.

If its oem fuel line there is a good chance its ok. I parted out some 90's model skis that still had great looking fuel lines and i save it to put on skis that have aftermarket fuel lines.

If you haven't had to do anything in 5 years your doing great. Myself, id go ahead and cut the wires back, replace the boots with screw on type, and go threw the carbs just for preventative maintenance. I pull my carb down once a year but i also run 10-20 gallons a gas threw it a week

 

[chevota84]

Update on mine, changed my lines out and moved my primer and there was no change, still idling high and seeing air in the lines. I'm going to rebuild the carb and see if a new diaphragm does it.

Sent from my SM-G930V using Tapatalk