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  1. #1
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    Default TSIO360FB fuel flow issue

    I purchased a 1979 Piper Dakota Turbo in December and have been having quite the adventure with getting a nice balance fuel adjustment and also getting the engine to shut down in ICO position. Now after getting the fuel pump rebuilt, having seals replaced in the throttle body and spider assy (manifold valve), and lastly finding out that the Merlin wastegate was installed backward and the unit was stuck in the fully closed position, we have repaired or replaced these components.
    The mechanic was finally able to get a nice balance fuel mixture with appropriate fuel flows and the engine would run smooth.....until mixture placed in ICO....then it will chug along for about a minute at 300RPM before finally shutting down.... Needless to say, two steps forward and one step back. My mechanic tested the ICO with the low electric pump and it was out of tolerance. Had a small stream coming out (the tolerance is less than 20 drops/minute. We sent the pump back to Central Cylinder in NE and they retested it every which was and could not find any leakage more than a drop, and that was at high pressure (20psi). My mechanic was test at about 6-9 psi.

    Any thoughts out there? Was wondering if it was possible that there is a check valve stuck in the vapor return or something like that. Completely clueless at this point. One final thing, the aircraft had an off-field landing in 2000 due to engine failure (controlled landing with no damage). But the wings had to be removed to transport the plane back to the field. IA removed and re-installed them. Plane has been flying since, about 700hrs.

  2. #2
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    Default

    Can you elaborate when you say you had the seals replaced on the throttle body/fuel servo? Was it overhauled or did were just the baffle seals replaced inside? What is the rise in RPM during idle cut-off?

  3. #3
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    Default

    I believe they were o-rings. Also the folks at Central Cylinder ran the fuel pump, throttle body and manifold valve on the bench at the same time. Everything checked out. Was was actually curious if the vapor return check valve was stuck open, would fuel come out of the fuel pumps supply line with the electric pump turned on and the mixture at ICO.

  4. #4
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    Default

    When you pull to ICO does the lever bottom out? or is there spring in it?

    I mean this is almost too simple to understand. If it is rigged correctly it should shut off if the parts are known to be good. Before you laugh, a LOT of rigging is not done correctly. Ensure lever for cutoff is hitting the stop.

    Another possible is timing, if the timing isn't correct it can run on after cut off, or if you have a ton of carbon deposits in the cylinders.

    And pardon my assumption, should not be a lot of playing with settings to get an engine to run correctly, you confident your mechanic has a clue?


    Anyhow


    Steve
    You never have a second chance, to make a first impression

  5. #5
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    Default

    What I would do is disconnect all fuel drain lines from the cylinders and see if fuel is present. If there is its either an obstruction or the check valve.