IO-360-A1A Power Surge in Cruise

[Cody Stallings]

#16 that's pretty funny.

Whats a Sniffle valve?

The prop governor is 3 years old. Bout 600hrs TT its a McCauley.

The mags should be in good shape, they are Bendix that were O/H the same time the injection system was.

[carusoam]

The sniffle valve is a check valve in the fuel system related to fuel injectors.  Excess fuel from the injectors collects in an area that has a drain line.  The ball floats off it's seat and allows fuel to drain out on the ground.  One direction, gravity holds the ball in place. The other direction the ball is kept in place by pin through the tube.  Dirt can allow the check valve to not perform it's job and allow some air up through the drain line.

Best regards,

-a-

[MB65E]

I thought Spark plugs originally? Ohm them out. Could be a cheap solution. Seems to be a rash of bad plugs showing up again. 

We used to run a ferry tank in the front seat of a Pitts special. Anything above 9.5k while on the AUX tank the engine would stumble. Pump on at altitude and it would run fine. I imagin you are sucking something other than fuel...See what your fuel P is before and after you slect the F pump. Running the F pump at altitude is not normal but could indicate a engine driven f pump issue or another fuel distribution issue. 

Or change R&R with an IO-720!

-Matt

[CWM20f]

I just had a champion plug quit with less than 200tt.  It's worth checking them for problems.  Wish I would have specified different plugs at overhaul. 

[Guest]

18 hours ago, Cody Stallings said:

#16 that's pretty funny.

Whats a Sniffle valve?

The prop governor is 3 years old. Bout 600hrs TT its a McCauley.

The mags should be in good shape, they are Bendix that were O/H the same time the injection system was.

The sniffle valve is a check/drain valve in the bottom of the intake plenum.  Mooney made them from an AN elbow, they drilled a small hole across the flared thread, inserted a small plastic ball and drove a pin through the hole to hold the ball in place.  

Engine vacuum sucks the ball closed, sealing the leak.  When the engine shuts off the ball opens allowing raw fuel to drain from the intake.  When they leak they really only effect idle mixture, making it lean.

Clarence

[Yetti]

http://www.donmaxwell.com/publications/MAPA_TEXT/External_Hoses/External_Hoses_Tubes.htm

[FloridaMan]

You don't suppose you could have a valve failing? 

http://www.avweb.com/news/savvyaviator/savvy_aviator_56_before_you_yank_that_jug-197497-1.html

[Cody Stallings]

Could be a Valve, or the check Valve. Not sure.

I pulled the injectors out of it to inspect an clean, 3 of them had a white chalky buildup around the orfic. One of them even had the build up inside the orfic.

All night soak in gun cleaning solvent really cleaned them up nice.

Engine seems to run a little better(might be in my head), but the problem did not go away completely. However, the EDM is acting right now after the cleaning.

Gonna keep digging, I will keep you guys posted.

[Guest]

31 minutes ago, Cody Stallings said:

Could be a Valve, or the check Valve. Not sure.

I pulled the injectors out of it to inspect an clean, 3 of them had a white chalky buildup around the orfic. One of them even had the build up inside the orfic.

All night soak in gun cleaning solvent really cleaned them up nice.

Engine seems to run a little better(might be in my head), but the problem did not go away completely. However, the EDM is acting right now after the cleaning.

Gonna keep digging, I will keep you guys posted.

Make sure you clean and install per Lycoming SI 1275C.

http://www.lycoming.com/Portals/0/techpublications/serviceinstructions/SI 1275C (09-23-2008)/Cleaning Fuel Injector Nozzles.pdf

Clarence