Super Jet I F'n Give Up! Need Help In East Orlando... [ NOT FIXED YET! ]

[retroicon]

Yes, pressure... when I open the tank, you can hear the air escaping.

So let's dig deeper here. If I'd primed the motor with a bunch of fuel, and then hit start, and it immediately revved up to almost wide open, even with the butterflies on the carbs barely open, could that be a result of there being fuel in the motor that got the motor fired, and because the motor didn't get more fuel from the carbs, it went lean causing the high revs?

-G

 

[r6487]

you have verified your fuel-in and fuel return lines are not accidentally reversed?

 

[WFO Speedracer]

Yes, pressure... when I open the tank, you can hear the air escaping.

So let's dig deeper here. If I'd primed the motor with a bunch of fuel, and then hit start, and it immediately revved up to almost wide open, even with the butterflies on the carbs barely open, could that be a result of there being fuel in the motor that got the motor fired, and because the motor didn't get more fuel from the carbs, it went lean causing the high revs?

-G

That sounds more like an air leak

 

[Matt_E]

Yes, pressure... when I open the tank, you can hear the air escaping.

So let's dig deeper here. If I'd primed the motor with a bunch of fuel, and then hit start, and it immediately revved up to almost wide open, even with the butterflies on the carbs barely open, could that be a result of there being fuel in the motor that got the motor fired, and because the motor didn't get more fuel from the carbs, it went lean causing the high revs?

-G

Air leak.

 

[WFO Speedracer]

Actually it sounds like a huge fawking air leak, whats happening is that you can't dump in enough fuel to keep the air fuel ratio correct, therefore it won't just light off pulling fuel from the carbs. I am not sure what you have going on there but its time to do a pressure test on the engine and find out. Engines will light off with the carb not even on the manifiold if you dump enough fuel in, I know I have done it a few times, but they act just like what you described, light off and rev to the moon till the fuel is gone, huge air leak = no carb signal = no run.

 

[retroicon]

I can 100% confirm it's not an airleak...

I've done multiple leakdown tests, and I'm holding 10lbs for 10 minutes without any loss of pressure on the testing setup. I'm testing by putting a freeze plug in both carb openings once removing the carbs, and another in the exhaust manifold after removing the headpipe. The leakdown tests were performed with the flywheel cover off as well.

-Gary

 

[retroicon]

you have verified your fuel-in and fuel return lines are not accidentally reversed?

Yes. I'm sure that the fuel lines are hooked up properly.

 

[QJS]

Remove the fuel in hose from the carb then pressurise the system as much as you can by blowing into the one way valve. Fuel should then be flowing from the fuel hose you have dis-connected. If it is not, check the fuel petcock and filters etc.
Chris.

 

[nightrider05]

It doesn't sound like the MSD could be the culprit, but my ski was running very strange last year and I thought it was fuel related. Ended up being that the MSD enhancer had shot . Swapped out a stock CDI and ski ran great.

Just curious if you have tried a different CDI. Once again I doubt this is the culprit here but you simply never know.

 

[retroicon]

I just spent about an hour going over everything, and decided to blow some more air through the checkvalve to make sure fuel was in the lines before I took the carbs apart again...

Well, I could blow through the lines, and blow, and blow until the point the tank looked like it expanded maybe a tiny bit ( either that or I was getting dizzy ), and no fuel was coming through the return line. I found a fuel line that had gotten pinched, and it was the line out of the petcock, and into the fuel pump on the carb...

Could this cause a runaway (fast revs up to 6k rpm or so, then died in under 5 seconds) type issue if I'd primed the ski, and it started using that fuel only... meaning, because of the pinched line, the fuel from the primer got into the cylinders, the spark plugs ignited that, but then no more fuel got into the carbs, so it burned up what was in the cylinders very quickly, causing a temporary lean condition until the fuel from the primer had burned off?

A lot of guys were guessing air leak, and I know it's not an airleak... so could the pinched line have caused the lean condition?

It's 4am here now and I can't start the ski since I live in a neighborhood with a HOA, and tons of kids...

Get your guesses in now on whether or not you think a pinched line could have caused the issues I've talked about, because I'm going to try to fire this thing as soon as I wake up tomorrow, and I'll report back...

-G

 

[Sospikey]

I think you found your issue! This is a typical lean-runaway that happens when your fuel lines aren't primed yet. It will start when primed, but run off when that small amount of fuel burns out. As always, WOT will stop the engine upon these types of runaways!

 

[WFO Speedracer]

I just spent about an hour going over everything, and decided to blow some more air through the checkvalve to make sure fuel was in the lines before I took the carbs apart again...

Well, I could blow through the lines, and blow, and blow until the point the tank looked like it expanded maybe a tiny bit ( either that or I was getting dizzy ), and no fuel was coming through the return line. I found a fuel line that had gotten pinched, and it was the line out of the petcock, and into the fuel pump on the carb...

Could this cause a runaway (fast revs up to 6k rpm or so, then died in under 5 seconds) type issue if I'd primed the ski, and it started using that fuel only... meaning, because of the pinched line, the fuel from the primer got into the cylinders, the spark plugs ignited that, but then no more fuel got into the carbs, so it burned up what was in the cylinders very quickly, causing a temporary lean condition until the fuel from the primer had burned off?

A lot of guys were guessing air leak, and I know it's not an airleak... so could the pinched line have caused the lean condition?

It's 4am here now and I can't start the ski since I live in a neighborhood with a HOA, and tons of kids...

Get your guesses in now on whether or not you think a pinched line could have caused the issues I've talked about, because I'm going to try to fire this thing as soon as I wake up tomorrow, and I'll report back...

-G

Yes this is the same scenario as me shooting carb cleaner down the intake with the carb off and it would have the same effect. I wont to expand on something QJS said, the proper way to prime the fuel system is to pull the return hose, blow pressure back through the return hose until fuel runs out the return fitting on the carb, it should not take a lot of pressure if tank is sealed properly and the one way valve is operational, but yes I believe you have found your problem. Closed throttle runaway can be cause but an air leak or a lack of fuel, both create the same type lean conditions.

 

[SuziQ]

Interesting thread...good luck this morning! :fingersx:

 

[retroicon]

I have BRAP!

Pinched fuel line, in conjunction with an idle stop screw that was open by an extra turn was the issue...

 

[SuziQ]

Cool ! Just let me know the next time you need for me to wish you luck, no problem and glad I could help.