Super Jet Problem with engine. Help needed

AAlamo

AAlamo

Location
Dalhart, TX
Hey guys, just bought a 97 superjet about 3 weeks ago and its already giving me trouble. Its got a 701, riva dry pipe, msd total loss, and mikunis (46 maybe?). Anyways I took it out to the lake a couple weeks ago and it ran great. good power band and throttle response. Then i took it to the ocean and didnt make it over the first set of waves before it died. So i brought it back up to shore and it started fine. Tested the compression and its about 130-135 per cylinder. Flushed it when i got home and put it away. This morning I checked the spark plugs, they were fouled so I cleaned them up, put them back in and started it up. As soon as I started it, it would rev really high and stay like that, almost as if I was pulling the throttle in but I wasnt touching it. I wasnt running water through it when I started it. So this leads to my question: is it something to do with the carbs and throttle? Or is there a hole in my case somewhere thats sucking in air? It seems the cases werent sealed great (just with silicone). I dont know much about engines and any help would be greatly appreciated on how to fix the high rev. Also if theres anyone in the central coast area who wouldnt mind taking a look at it to try to diagnose it/ fix it I would greatly appreciate it.
Thanks
Anthony
 
S

Schmidty721

someone turf my rails
Location
WI
Lots of possibilites here. If you search the forum for the terms "air leak" you will find some good threads of people trouble shooting the same issues.

Air leak could be anywhere at this point. Cases, Intake, fuel line, crank seals, etc.
Could also be an issue of plugged fuel filters, carbs etc. causing it to run lean and rev.
I would start with simple things such as check all of the fuel line, connections, filters. Make sure the carbs & intake are all tight. Look for signs of oil/gas seeping out on gasket surfaces and/or crank seals. Report back on items you have ruled out and you'll get advice from people that have been down the this road before
 
AAlamo

AAlamo

Location
Dalhart, TX
Okay so this afternoon I ended up tearing apart the ski completely and did find some useful info: most of the gaskets had quite a bit of wear and the intake gasket was definitely the worst (possibly the cause). So I plan on replacing all of them...I also found that there was quite a bit of unburnt fuel in the pistons. So although the carbs might be running lean, why is there this unburnt fuel? And if anyone is looking to buy a msd total loss and ebox I think Im going to put mine up for sale and get a stock one. I will put them up in the for sale thread
 
nightrider05

nightrider05

Location
St.Louis Missouri
Just a heads up since nobody else mentioned it...

A lean runaway can be a scary thing when it actually happens. A true lean runaway will leave you baffled...you will pull the lanyard and the ski will keep running...you can pull the spark plug wires(will getting the crap shocked out of you if lanyard is still in) and the ski will keep running.

There are a few ways to shut a lean runaway ski off....First and easiest...block the flow of air either going in, or exiting. I typically find it easiest to block the exhaust, as its just a hole in the back and is never restricted or blocked. Simply taking your hands and blocking off the hole will cause motor to shut down quick since it cant breath. if your flame arrestors are off you can also block the air intake..will quickly shut motor off. The other option is to pull the choke, which is basically doing the same thing as blocking off your air intake.
 
nightrider05

nightrider05

Location
St.Louis Missouri
Ya it can be quite scary the first time...and I think everyone goes through the exact same motions...pull lanyard, pull plug wires...then go into panic mode and to try to whatever you can to kill motor before it commits suicide.
 
Cannibal

Cannibal

Tasty Human
Location
Summit Lake, WA
AAlamo said:
Okay so this afternoon I ended up tearing apart the ski completely and did find some useful info: most of the gaskets had quite a bit of wear and the intake gasket was definitely the worst (possibly the cause). So I plan on replacing all of them...I also found that there was quite a bit of unburnt fuel in the pistons. So although the carbs might be running lean, why is there this unburnt fuel? And if anyone is looking to buy a msd total loss and ebox I think Im going to put mine up for sale and get a stock one. I will put them up in the for sale thread
Click to expand...

Take a picture of your pistons and post it up here. Might be normal, might not be. Let's take a look.
 
jetpilot36

jetpilot36

Location
Fort Worth
nightrider05 said:
Just a heads up since nobody else mentioned it...

A lean runaway can be a scary thing when it actually happens. A true lean runaway will leave you baffled...you will pull the lanyard and the ski will keep running...you can pull the spark plug wires(will getting the crap shocked out of you if lanyard is still in) and the ski will keep running.

There are a few ways to shut a lean runaway ski off....First and easiest...block the flow of air either going in, or exiting. I typically find it easiest to block the exhaust, as its just a hole in the back and is never restricted or blocked. Simply taking your hands and blocking off the hole will cause motor to shut down quick since it cant breath. if your flame arrestors are off you can also block the air intake..will quickly shut motor off. The other option is to pull the choke, which is basically doing the same thing as blocking off your air intake.
Click to expand...

if your engine is revving all to hell because its sucking in too much air,then i dont think blocking the carbs will shut it off because its still getting air from the leak(wherever that is).but if the air leak isnt that big,blocking the carbs should flood it out.i like the idea of plugging the exhaust though.(banana in tailpipe)
 
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