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| Username | Post: YS61ST2 blowing fuel out carb??? | |
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mudbogger2 Member Posts 65 |
 01-10-02 07:22 PM - Post#3705
After my last flight of the day I shut the engine off and went to the bench with my heli. Looked down and saw fuel everywhere. I noticed it was pouring out the carb! I released the pressure from the tank and it stopped. Never done that before. Should I be worried? Jon |
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rickc Senior Member Posts 135 |
 01-10-02 08:15 PM - Post#3706
Your check valve is bad. Replace it and you'll be back to normal. Rick
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Maxx Senior Member Posts 304 |
01-10-02 09:47 PM - Post#3707
If you had fuel in the tank and didn't release the pressure then, yea, the fuel will be forced out of the carb! Your check valve is doing just what it should...keeping the pressure in the tank from bleeding back into the crankcase! When you land after a flight you need to get in the habit of releasing the pressure even before you switch off the radio! It doesn't take a second for the pressurized fuel tank to fill your engine (or your tabletop) with fuel! Chris
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rickc Senior Member Posts 135 |
01-10-02 10:16 PM - Post#3708
Maxx your answers porked, I've flown YS engines for over 10 years. How many do you own? Im suprised you havn't seen these symptoms. If the check valve is good you can hold tank pressure for hours and not cause the engine to flood or to percolate fuel out the carb. To put it in laymen’s terms. The pressure will leak backwards through the check valve and will pressurize the crankcase. The pressure in the crankcase will find it's way down the center of the crankshaft and to the diaphragm and tickle it causing the diagram and plunger to regulate a small fuel flow. The fuel will find it's way out the carb because it's an exit for the pressure. (Lowest resistance) I release my pressure after flying, but just to ease the pressure off the tank and fuel system. Or to make sure I don’t forget to do it prior to refueling and get a face full of fuel. Rick [This message has been edited by rickc (edited 01-12-2002).]
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mudbogger2 Member Posts 65 |
01-11-02 02:32 AM - Post#3709
Thanks guys. I think I will just replace the valve. I always release the pressure off the tank usually within 30 seconds of shutting off the engine. This was the first time it had done this in 2 gallons of fuel. |
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Maxx Senior Member Posts 304 |
 01-11-02 06:22 PM - Post#3710
rickc; I answered mudboggers question based on MY experience with the YS engines, both airplane and Helicopter from the past 6+ years! As of right now I have 5 YS engines; 120's 61ST2's and 80's (just to answer your query). BTW, to put it in laymans terms; Query is another term for Question! I DO thank you for the information on the YS engines, however, if you must reply to one of my posts in such a Caustic and uncalled for manner, might I suggest you add a "P" to your tag when you log on next time! Maxx [This message has been edited by Maxx (edited 01-11-2002).]
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Griddly Senior Member Posts 184 |
01-11-02 06:42 PM - Post#3711
rickc , take it easy man! |
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Steve Walker Senior Member Posts 397 
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01-12-02 12:56 AM - Post#3712
Maxx, he needs to add more than just a "P" to his nick. Did you read his response to my post on the "JR 10X" thread? Calling his posts "Caustic" is putting it mildly! Steve
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rickc Senior Member Posts 135 |
01-12-02 01:21 AM - Post#3713
Well, my posts are helpful and to the point at first. Your post was and is now made strictly to stir things up. You contribute nothing but sarcasm. You took a jab and I poked back. I didn't start a thing. But it bothers me to read your sarcastic comments and not to reply. Rick |
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mudbogger2 Member Posts 65 |
01-12-02 02:41 AM - Post#3714
Ok I went to buy a new check valve. The LHS had a 1.20 check valve. He said they were the same as the heli engine valves but cheaper? If I buy the one for the airplane engine will it work? are they the same? $6.59 for the airplane one and $10.95 for the heli one. |
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rickc Senior Member Posts 135 |
01-12-02 03:04 AM - Post#3715
For what I am aware of you need the one made for the ST-2, ST3. They are different inside. The plank versions have a diaphragm, a ball and a spring. The heli version has a diaphragm, a spring and something that resembles the end of a valve stem removal tool. Anyway they are different. My instructions with my YS80 states to only use the check valve specifically designed for the ST-2, ST-3. I believe the heli version is made to hold up to a higher sustained rpm. Either version will work but the heli version I would think would probably last longer. The part # you need is YS2510. Rick [This message has been edited by rickc (edited 01-12-2002).]
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Dyehard Senior Member Posts 272 |
01-12-02 06:34 AM - Post#3716
You can use the four stroke check valve, part number 0405,with the ST2, it works better that the original. Rick C, pardon me for not understanding your explanation, but from what I've learned of how the YS regulator works, I don't see how the check leaking would couse fuel to run out of the carb. The regulator diaphram is picked up by suction, the faster the engine runs, the higher the negative pressure in the carb and that opens the regulator more. If you presurize the crankcase, which could only happen if the piston stopped high enough to close off the exhaust port, that would put pressure on the diaphram, causing it to close the regulator stopper even tighter than it would be at rest. A piece of foreign matter could cause a leaky regulator, and some of them just have a tendency to leak, I have a friend that has an ST2 in his Futura, it has leaked through the carb since day one, if he doesn't bleed the pressure or clip off the line going to the carb. It has had at least three new checks, the newest one a 0405, and it has leaked with all of them. Other than the carb leak, it runs great. If you can show any flaws in my reasoning, I would be glad to liston.
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rickc Senior Member Posts 135 |
01-12-02 07:21 AM - Post#3717
Hello Dyehard, This is for YS engines in general. Some are plumbed a bit differently but the theory is the same. If you take off the regulator assembly, you will see a cavity in the engine case with two holes "Except for the 1.40 and heli". The center hole is where the pressure comes in from the crankshaft. The hole that is drilled at an angle is for the pressure going to the tank on the 4 cycles, off the backplate on the heli engines. As you turn the crankshaft, you will notice the center hole will open up. This is when the crankcase pressure will push on the diaphragm. At that moment the plunger will open and fuel will pass through the regulator and into the carburetor. As the crankshaft’s hole passes the opening, this will drop the pressure in the cavity and the regulator plunger will close stopping fuel from passing to the carburetor. This all happens via crankcase pressure. By turning the screw on the bottom of the regulator or on the side of a ST-2 & ST-3 you control the length or stroke of the plunger. These are usually factory set and need not be messed with,(sealed on the heli engines) This is how you set the low end adjustment on the 4 cylcle YS engines. If the check valve is bad the tank pressure will bleed back keeping the crankcase pressurized and depending on the stopping position of the crankshaft the center hole will direct the sustained pressure to the diaphragm and keep the plunger open to allow fuel to flow to the carb. I hope this helps. Rick [This message has been edited by rickc (edited 01-12-2002).]
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DavidH Senior Member Posts 1555 |
01-12-02 03:14 PM - Post#3718
Well I for one will agree with Maxx on this one. The Check Valve is too keep the tank pressurized and has nothing to do with fuel leaking out of the carb when the engine is sitting in the off mode. If the check valve was bad the tank would hold no pressure and then there is no way fuel would be forced out of the carb. I have also ran YS engines in helis for 6 years and I have a fuel cutoff that I close as soon as I land the heli at the end of the flight to keep fuel from pouring in the carb and flooding the engines. Don't know much about YS aero engines but this is always the way I have had to do my heli engines. I see all the Pros that run YS doing the same thing, they either have a fuel cut off or they release the pressure as soon as they land. David |
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Dyehard Senior Member Posts 272 |
01-12-02 07:07 PM - Post#3721
Rick, you are exactly right in your description of how the YS regulator works, it's been a while since I have taken one apart and I remembered the pivot for the regulator valve being on the opposite side. So much for memory. However, the engine would still have to stop with the piston blocking the exhaust port to pressurize the crankcase, so turning the crank would eliminate any pressure and stop the carb leaking. I would have thought that the rotory valve in the carb would leak enough to elliminate any pressure buildup, I can blow through the one I have sitting on the bench even when it is fully closed, maybe some seal better than others. A lot of maybe's, as I have had checks go out to the point the engine wouldn't run, yet the carb didn't leak, and I've seen one engine leak everytime the tank is pressurized, even with a brand new check installed, yet it runs great. But assuming the piston stops in the right place and the rotory valve seals well enough, yes, I could see that a leaking check could cause the regulator to open and allow fuel to flow.
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rickc Senior Member Posts 135 |
01-12-02 09:15 PM - Post#3722
I agree that the stopping position on the crankshaft could be a factor in the fuel leakage. Rick
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rickc Senior Member Posts 135 |
01-13-02 05:04 AM - Post#3719
I'm not sure how else to explain it, YS crankshafts are hollow, pressure in the crankcase travels down through the center of the crankshaft. At the regulator assembly there is a small home in the crank that allows air pressure to push against the diaphragm, the diaphragm pushes the plunger and when the plunger moves this will allow a fuel flow to the carb. If the check valve is bad this allows pressure to leak back into the crankcase it will travel down the hollowness of the cranks and find it's way to the diaphragm. The pressure will move the diaphragm thus also moving the plunger and will allow a constant fuel flow to the carb. Just remove your check valve and replace it with a straight fitting. You will see what I mean. I will admit the only engines I have seen do this are the 4 cycles. Other factors would need to be met in the 2 cycles. Like the stopping position on the crank and the throttle barrel being closed off to maintain crankcase pressure. The only other area I can think of having problems would be having debris in the regulator and not allowing it to seal. This would allow the fuel to also leak if the check valve was good. All in all I still stand on if the check valve is good and the plunger is sealing off the fuel, as it should. Your system should hold pressure and not leak or flood the engine. I stop ST-2 & 3 at the end off the flight with a fuel cut off device, but just not to allow un-burnt fuel to remain in the engine. Rick [This message has been edited by rickc (edited 01-13-2002).]
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DavidH Senior Member Posts 1555 |
01-13-02 05:42 AM - Post#3720
Well I have had a straight fitting in the pressure line before. And the carb would not pour out fuel. I was doing this experiment to see what the engine would do without the check. When I have bad check valves the only problem I have experienced is the engine will not run correctly and is usually going lean as a sign the check valve is bad. I will ask all the YS gurus I fly with if the carb pouring fuel and the engine flooding when the engine is off and the pressure is not released a sign that the check valve is bad. Those guys would just be Cliff Hiatt, Wayne Mann, they have been flying YS engines for years and the only problem they have when a check valve is bad the engine will not run correctly. David |
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Dyehard Senior Member Posts 272 |
01-13-02 04:40 PM - Post#3723
I just had a thought, one reason I may have never had this problem is that I use throttle cut on my 9Z to kill the engine, as soon as you turn the switch loose, it opens the throttle slightly, which would eliminate the possibility of any pressure buildup in the crankcase. That suggests a check to see if the check valve is starting to leak, simply open the throttle and see if the fuel leakage from the carb stops. If it stops, then it would be a check valve going bad, if not, the problem is in the regulator.
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mudbogger2 Member Posts 65 |
 01-13-02 10:36 PM - Post#3725
Ok guys I replaced the check vale. Went to start the engine and it was hydro-locked. I removed the plug, fuel line adn pressure line and spun it till it was clear. Hooked it all back up and it did it agian! cleared it out once more and while starting I noticed it was spitting small amounts of fuel out the carb while I was spinning it over(flooded agian). Something is very wrong here. Any Ideas? It will probably be monday night before I get to look inside it te see if something is bad. Thanks for all the help. Jon [This message has been edited by mudbogger2 (edited 01-13-2002).]
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rickc Senior Member Posts 135 |
01-13-02 11:29 PM - Post#3726
While your filling the tank are you blocking off the supply to the carb with a fuel line clip or hemostats? I see I'm going to be eating my words. It can't be a major issue. Seems like it had to be the check valve or the diaphragm or plunger. Anyway, something is broken. If all parts are working properly the YS should not flood and will hold pressure for hours. If you run any type of after run oil and it's petroleum based you will cause damage to the diaphragm. "P" Rick |
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mudbogger2 Member Posts 65 |
 01-14-02 01:45 AM - Post#3727
I always filler up from the fuel inlet going to the carb. Never used after run oil just ran it dry at the end of the day. Hopefully I will see what is going on when I tear it down. Never been inside one of these. Looks like it will be fun. |
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rickc Senior Member Posts 135 |
01-14-02 05:19 AM - Post#3724
Excellent point. Rick
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Dyehard Senior Member Posts 272 |
01-14-02 01:18 PM - Post#3728
Two things to look for, something is holder the regulator valve open, such as a piece of foreign matter, or the diaphram has a hole in it. Either one would allow fuel to go into the engine unobstructed.
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rickc Senior Member Posts 135 |
01-14-02 06:10 PM - Post#3730
That’s the way they are intended to work if all it correct. My theory has proven correct at the field a couple times on plank engines. Changed the check valve and things were back 100%. Apparently I made a bad call on this one. Neither my ST-2 nor my ST-3 will leak fuel with pressure left in the tank. The plunger will have to be hanging open for some reason to allow flow of fuel. I never use castor, as that is bad for YS. I can't think of anything else besides debris in the regulator or castor has it gummed if castor was used. Rick |
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mudbogger2 Member Posts 65 |
 01-15-02 02:18 AM - Post#3731
I think I found the problem. After tearing the engine down I found the little lever inside the diaphram was moving too far. A small piece of silicone?? was supposed to be glued in place to keep it from traveling too far I think. Anyhow it had fell down under the little lever! I repositioned the piece of silicone and will try it in the morning if it doesn't work I will probably get a new regulator. <fingers crossed> |
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Ergo60 Senior Member Posts 186 |
01-15-02 05:39 AM - Post#3729
OK, I have to jump in on this one. I use a YS61ST2 in my Ergo 60. And while I have only used it for a year I have NEVER had it leak out the carb, and since I fly mostly at my house I have on numerous occasions left the pressure in the tank. I go out after a few days, and the pressure is still there, and no fuel has leaked into the carb. I have NEVER seen it happen on the bench or at the field. Like I said this is the first year I have used the YS, so I was not used to having to release the pressure, so it went pressurized many times, and like stated before I have NEVER had it leak into the carb. Maybe I am super lucky, or maybe the planets are aligned just right. The only thing I have had happen is a main fuel tank split at the seam, but that was because I was using the stock flimsy foam for the tank around the frame, I have since then switched to small rubber hose that I slit to fit over the frame. This is not gospel, but it is what I have observed.
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Dyehard Senior Member Posts 272 |
01-15-02 12:33 PM - Post#3732
The piece of silicone that you describe is the plug the stops the fuel by covering the inlet tube. The glue the holds it in place must have broken loose. Just moving it back in place won't work, it will just move again, and I don't know of any commercially available glue that would hold up emmersed in fuel. You will have to replace the whole lever, if available, or the complete regulator. It the engine still under warranty?
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