mudbogger2
Member
Posts: 65
Loc: Hoschton, Ga.
Reg: 11-22-00
|
 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
|
rickc
Senior Member
Posts: 135
Loc: Green Valley IL. USA "Tor...
Reg: 05-13-01
|
 01-10-02 08:15 PM - Post#3706
In response to mudbogger2
Your check valve is bad. Replace it and you'll be back to normal.Rick
|
Maxx
Senior Member
Posts: 304
Loc: Shreveport, Louisana, U.S...
Reg: 02-16-01
|
01-10-02 09:47 PM - Post#3707
In response to rickc
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
| " Experience is what you get when you don't get what you expected..." |
|
rickc
Senior Member
Posts: 135
Loc: Green Valley IL. USA "Tor...
Reg: 05-13-01
|
01-10-02 10:16 PM - Post#3708
In response to Maxx
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).]
|
mudbogger2
Member
Posts: 65
Loc: Hoschton, Ga.
Reg: 11-22-00
|
01-11-02 02:32 AM - Post#3709
In response to rickc
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.
|
Maxx
Senior Member
Posts: 304
Loc: Shreveport, Louisana, U.S...
Reg: 02-16-01
|
 01-11-02 06:22 PM - Post#3710
In response to mudbogger2
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).]
| " Experience is what you get when you don't get what you expected..." |
|
Griddly
Senior Member
Posts: 184
Loc: Nashville, TN
Reg: 01-07-01
|
01-11-02 06:42 PM - Post#3711
In response to Maxx
rickc , take it easy man!
|
Steve Walker
Senior Member
Posts: 397
Loc: Cincinnati, Ohio USA
Reg: 07-24-01
|
01-12-02 12:56 AM - Post#3712
In response to Griddly
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
|
rickc
Senior Member
Posts: 135
Loc: Green Valley IL. USA "Tor...
Reg: 05-13-01
|
01-12-02 01:21 AM - Post#3713
In response to Steve Walker
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
|
mudbogger2
Member
Posts: 65
Loc: Hoschton, Ga.
Reg: 11-22-00
|
01-12-02 02:41 AM - Post#3714
In response to rickc
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.
|
rickc
Senior Member
Posts: 135
Loc: Green Valley IL. USA "Tor...
Reg: 05-13-01
|
01-12-02 03:04 AM - Post#3715
In response to mudbogger2
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).]
|
Dyehard
Senior Member
Posts: 272
Loc: Richlands, Va.
Reg: 01-27-01
|
01-12-02 06:34 AM - Post#3716
In response to rickc
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.
|
rickc
Senior Member
Posts: 135
Loc: Green Valley IL. USA "Tor...
Reg: 05-13-01
|
01-12-02 07:21 AM - Post#3717
In response to Dyehard
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).]
|
DavidH
Senior Member
Posts: 1555
Loc: Birmingham,AL .
Reg: 05-31-01
|
01-12-02 03:14 PM - Post#3718
In response to rickc
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
|
Dyehard
Senior Member
Posts: 272
Loc: Richlands, Va.
Reg: 01-27-01
|
01-12-02 07:07 PM - Post#3721
In response to DavidH
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.
|
rickc
Senior Member
Posts: 135
Loc: Green Valley IL. USA "Tor...
Reg: 05-13-01
|
01-12-02 09:15 PM - Post#3722
In response to Dyehard
I agree that the stopping position on the crankshaft could be a factor in the fuel leakage.Rick
|
rickc
Senior Member
Posts: 135
Loc: Green Valley IL. USA "Tor...
Reg: 05-13-01
|
01-13-02 05:04 AM - Post#3719
In response to DavidH
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).]
|
DavidH
Senior Member
Posts: 1555
Loc: Birmingham,AL .
Reg: 05-31-01
|
01-13-02 05:42 AM - Post#3720
In response to rickc
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
|
Dyehard
Senior Member
Posts: 272
Loc: Richlands, Va.
Reg: 01-27-01
|
01-13-02 04:40 PM - Post#3723
In response to rickc
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.
|
mudbogger2
Member
Posts: 65
Loc: Hoschton, Ga.
Reg: 11-22-00
|
 01-13-02 10:36 PM - Post#3725
In response to rickc
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).]
|
