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All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Glow Engines >> ys91fz quits only when pulling neg g's
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ys91fz quits only when pulling neg g's - 11/24/2002 10:34:42 PM   
kr79


 

Posts: 7
Joined: 11/24/2002
From: yuba city, CA, USA
Status: offline 		I am having problems with my 91 fz only when pulling negative g manuevers. engine just quits. any help would be appreciated
       Post #: 1

ys91fz quits only when pulling neg g's - 11/24/2002 10:41:42 PM   
w8ye



Posts: 18981
Joined: 12/11/2001
From: Taylortown, OH, USA
Status: offline 		It might be a good time to review your system. Eventhough the Y-S is supposed to not be sensitive to tank position and attitude, as you can see, they sometimes are.

Your tank still should be centered on the needle valve for best performance. Your tank should be as close behind the engine as possible.

You need to determine that the fuel system is still pressurized after running the engine.

You also could review your mixture level. The engine is quiting because it is too lean. Maybe if you richened it up a little, the problem would be subdued.

_____________________________

Attended the CutFinger Institute of DirtNap University for years but never did graduate....

Club Saito Member #7
Original AMA #31261

(in reply to kr79)
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ys91fz quits only when pulling neg g's - 11/25/2002 5:51:20 AM   
CP140



Posts: 801
Joined: 7/1/2002
From: Vancouver, BC, CANADA
Status: offline 		I know nothing about the "plumbing" of this engine, but I assume it has a clunk like others do (if not, then ignore this!)... just wondering, is your clunk free to move to the top of the tank or is it binding on the back wall of the tank... just a thought for what it's worth

(in reply to kr79)
       Post #: 3

ys91fz quits only when pulling neg g's - 11/25/2002 8:02:39 AM   
perdo


 

Posts: 189
Joined: 4/4/2002
From: Lubbock, TX, USA
Status: offline 		Put a new valve cover gasket on it.

Just my $0.02 worth

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ys91fz quits only when pulling neg g's - 11/25/2002 11:51:14 PM   
visioneer_one



Posts: 2423
Joined: 12/12/2001
From: St. Thomas, VIRGIN ISLANDS (USA)
Status: offline 		[QUOTE]Originally posted by CP140
I know nothing about the "plumbing" of this engine, but I assume it has a clunk like others do (if not, then ignore this!)... just wondering, is your clunk free to move to the top of the tank or is it binding on the back wall of the tank... just a thought for what it's worth [/QUOTE]
Definitely check the clunk. I lost a Sukhoi during a slow inverted pass for exactly that reason.

(in reply to kr79)
       Post #: 5

Clunk - 11/26/2002 4:24:18 AM   
RLDIII


 

Posts: 350
Joined: 3/9/2002
From: Spring, TX, USA
Status: offline 		Yup, I would agree to take a long hard look at the clunk as a POSSIBLE source of the problem. The tank pressurization used by YS engines does go a long way towards keeping them from changing the way they run in different attitudes, but all that tank pressure does no good IF the clunk is not free to follow the fuel to the top of the tank in a negative "G" move! If that is the case, they will suck air and die like any other engine!

Lee

_____________________________

Test pilots get to play with other folks toys!

(in reply to kr79)
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ys91fz quits only when pulling neg g's - 11/26/2002 5:08:55 AM   
Ladyflyer



Posts: 1035
Joined: 1/13/2002
From: North Am, PA, USA
Status: offline 		CLUNK !

_____________________________

LF
When they have to say "NO FEAR" it really means NO SENSE.

(in reply to kr79)
       Post #: 7

ys91fz quits only when pulling neg g's - 11/26/2002 7:01:49 AM   
kr79


 

Posts: 7
Joined: 11/24/2002
From: yuba city, CA, USA
Status: offline 		I checked the clunk and no problems there. I dont know what changing the valve cover gasket would make. I have richened the needle,and leaned the needle and still have the problem. Its driving me crazy...

(in reply to kr79)
       Post #: 8

ys91fz quits only when pulling neg g's - 11/26/2002 7:27:44 AM   
perdo


 

Posts: 189
Joined: 4/4/2002
From: Lubbock, TX, USA
Status: offline 		If the valve cover gasket leaks on a YS the regulator doesn't work properly There for it can go lean doing certain maneuvers.

(in reply to kr79)
       Post #: 9

ys91fz quits only when pulling neg g's - 11/28/2002 10:36:31 AM   
kr79


 

Posts: 7
Joined: 11/24/2002
From: yuba city, CA, USA
Status: offline 		ok I will check the valve cover and gasket..

Thanks for all your imput

(in reply to kr79)
       Post #: 10

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