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Thread: IO360 hot starts

  1. #1
    jimboflying's Avatar
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    IO360 hot starts

    Why are fuel injected engines difficult to start when hot?
    What is the best technique to use for hot starts?

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    If fuel vaporizes in the injector lines on top of the engine.

    So always shut down facing into whatever wind you may have and if possible open the oil fill door for thru ventilation. Not per the book but on my 180 I hit the prime pump with full mixture and throttle for a few seconds to compress the fuel in the lines, then pull the throttle back to about fast idol and crank to start then catch it with the prime pump if it stumbles after it fires.
    Remember, These are the Good old Days!

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    Crappy ignitions. Add a good electronic ignition and hot start problems will be a distant memory.

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    Usually fuel related. For my AEIO 360, I have found that cracking the throttle, placing mixture to cutoff, activating the pump, then momentarily "blip" the mixture part in then back out. Turn the pump off.

    Then wide open throttle, mixture cutoff, and crank. Takes ten blades. Start, mixture full forward, throttle to idle. Don't waste any time moving either of those controls. Works for me.

    others may have better ways. See above, which were typed while I was typing.

    Another thing that helps: fine wire plugs on the bottom.
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  5. #5
    www.SkupTech.com mike mcs repair's Avatar
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    Quote Originally Posted by bob turner View Post
    Then wide open throttle.. and crank.
    I was running for my fire extinguishers reading that....

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    IO 720 was the worst.
    Flood.
    Mixture lean.
    Full Throttle.
    Starts 100 % of the time.
    Then perfect and tailor your procedure.
    Electronic ignition is also a game changer.

  7. #7
    Steve Pierce's Avatar
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    Quote Originally Posted by bob turner View Post
    Usually fuel related. For my AEIO 360, I have found that cracking the throttle, placing mixture to cutoff, activating the pump, then momentarily "blip" the mixture part in then back out. Turn the pump off.

    Then wide open throttle, mixture cutoff, and crank. Takes ten blades. Start, mixture full forward, throttle to idle. Don't waste any time moving either of those controls. Works for me.

    others may have better ways. See above, which were typed while I was typing.

    Another thing that helps: fine wire plugs on the bottom.
    That is how I was taught to start the Carbon Cub FX3 with the fuel injected 360. Works every time.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

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    skywagon8a's Avatar
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    Quote Originally Posted by jimboflying View Post
    Why are fuel injected engines difficult to start when hot?
    What is the best technique to use for hot starts?
    Because when hot, the residual heat expands the fuel in the injector lines squirting the fuel into the intake where it pools making an over rich mixture for the next start unless you let it sit for a half hour or more. That is the noise you are hearing after shutdown.

    The Lycoming IO-360 start procedure depends on whether the fuel tank is below the engine or above since part of the start involves being certain that there is fuel with no air bubbles at the intake of the engine driven fuel pump. This is why the aux fuel pump is turned on, to pressurize the engine driven pump. IF there are air bubbles at the inlet to the engine driven pump when the engine starts and you push the mixture rich, the engine will quit due to lack of fuel (air bubble). At this point you will have no idea whether you need fuel or are too rich.

    Treat the mixture control like a fuel valve. Leave it in idle cutoff. Turn on the boost pump to pressurize the engine pump. As long as the mixture is in idle cut off the boost pump can remain running. If you place the mixture towards rich even a little bit prior to cranking the engine it will flood. Assume the engine has enough fuel due to the above heat filling the intake. Crank the engine, when it fires modulate the mixture towards full rich as the rpm builds up. Remember that while below idle speeds it doesn't take much opening of the mixture control to make the mixture too rich.

    If you have turned off the boost pump after pressurizing the engine pump and the engine stops during the start procedure or begins to stop, turn on the boost pump and modulate the mixture control. Remember that when a fuel pump is running there is fuel available to flow at the mixture control valve. Use of the mixture control is key.

    Be aware of your mixture control setting, your boost pump on/off setting, high or low fuel tank, keeping in mind your particular airplane configuration. Air bubbles anywhere = no fuel flow. The engine is not running until it can idle on it's own. Some airplanes need the boost pump running on the ground during very hot days when the engine is at low RPMs because the fuel flow is so low air bubbles can form anywhere in the lines.

    If your Lycoming fuel injected engine sounds like it wants to quit during ground operations on hot days, just turn on the boost pump to squeeze the air bubbles.

    Yes an electronic ignition system will help but still keep in mind the procedure.
    N1PA
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  9. #9
    Speedo's Avatar
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    Quote Originally Posted by mike mcs repair View Post
    I was running for my fire extinguishers reading that....
    I can’t speak for IO360s, but the way to start a balky IO540 is to flood it, then throttle forward, mixture to idle cutoff, and crank it. Once it catches bring the throttle back and mixture forward approximately simultaneously. No fires yet.
    Speedo

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    mvivion's Avatar
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    You need to understand that there are fuel injection systems, and then there are fuel injection systems. Lycoming uses a somewhat different system than Continental.

    I have ave found that, in general, closely following the manufacturers recommended procedures is a good place to start.

    That said, as Pete points out, understanding how the system in YOUR airplane works is essential to success.

    In my experience, the internet is a poor place to look for information on starting an engine, particularly if you don’t specify the precise engine and installation. And this is a case in point: Both Lycoming and Continental built “IO 360” engines. And the fuel injection systems are different between the two.

    MTV
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    hotrod180's Avatar
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    Quote Originally Posted by skywagon8a View Post
    Because when hot, the residual heat expands the fuel in the injector lines squirting the fuel into the intake where it pools making an over rich mixture for the next start unless you let it sit for a half hour or more. …..
    Maybe not feasible in a C185, as I understand the fuel shutoff (separate from the fuel selector) is woired open,
    but what about running the system dry -- as in killing the engine by turning the fuel selector to "off"?
    If the lines are dry, there's no fuel in them to expand.
    (I've never operated a FI airplane engine, so pardon me if my ignorance is showing )
    Cessna Skywagon-- accept no substitute!

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    To expand a little on what MTV said above, "I have ave found that, in general, closely following the manufacturers recommended procedures is a good place to start." (I always pay close attention to Mike's advice, I've learned a LOT this way), an example would be the Aviat Husky with Lycoming IO-360, which I've been flying regularly (but please don't tell my mother ). Normal hot start goes like this, based on POH, and assumes key start:
    -Throttle forward ~1/2-3/4" (that's less than an inch, NOT 1/2 or 3/4 of full travel)
    -Mixture idle cutoff
    -Crank engine, SLOWLY advancing mixture until engine catches, usually 1 to 4 blades

    Note: NO boost pump on normal hot start. Once in a great while it will surge and threaten to die after this procedure, then maybe a brief blip of boost pump to purge lines, but rare in my experience.

    If it doesn't start in <10 blades, do flooded hot start:
    -Mixture and throttle at least half way forward
    -Boost pump on 1-4 seconds, only until fuel flow showing on gauge, then off
    -Throttle full forward
    -Mixture to idle cutoff
    -Crank engine, while SLOWLY advancing mixture; pause when it starts to catch, then throttle back and mixture forward as it settles in. It will sometimes "bark" on this procedure, but hey, it's a Husky.

    The other BIG thing is to make sure that magneto timing is correct, and that the appropriate mag service bulletin or A.D. has been complied with, as this can have a big effect on timing. As bottom sparkplugs lead up, ~40-50 hours can get harder to start; fine wire plugs help here. Erosion on inside of the air filter is a sign of incorrect timing, probably from backfire through intake: This is NOT good for many reasons.

    Hope this helps.

    Thanks. cubscout

  13. #13
    mvivion's Avatar
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    Quote Originally Posted by hotrod180 View Post
    Maybe not feasible in a C185, as I understand the fuel shutoff (separate from the fuel selector) is woired open,
    but what about running the system dry -- as in killing the engine by turning the fuel selector to "off"?
    If the lines are dry, there's no fuel in them to expand.
    (I've never operated a FI airplane engine, so pardon me if my ignorance is showing )
    There are no Lycoming IO 360 engines in Cessna 185s. The 185 has a Continental fuel injection system, with a return line. And none of the 185s I’ve flown had fuel shutoff wired shut. BTW, the fuel selector was an option on at least early 185s.

    MTV
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  14. #14

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    I've flown a couple '61 C185's that had the fuel shutoff on the control panel - no wiring. My experience is that 185 fuel selectors do not have an "Off" position. 180 yes, 185 no. The later 185 fuel shutoff handles have a push button to operate, similar to the flap handle.

    Hot starts? Go directly to the POH.

  15. #15

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    We have new pilots who go directly to the POH for everything.

    After takeoff checklist:
    throttle - Full
    airspeed - 64-72 kts
    cowl flaps - open
    flaps - retract

    I said - "you actually read that stuff after takeoff?" Answer: "yes". I have yet to actually see anybody reading anything after takeoff (except in jets).

    My Decathlon POH actually has ten checklist items for takeoff and climb. It has no hot start procedure.
    You will be a busy dude, reading "raise tail" - check!
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  16. #16

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    Starting old school fuel injection with old school mags must be different than new tech fuel infection with electronic ignition and auto spark plugs. No POH for my Cub and hot starting is a total non-issue. Start it hot just like starting cold. Prime it and crank it. It fires right up.

    I never had any problems hot starting my old Continental IO-360, either. When building this Cub I considered adding a fuel return like Continental uses but with a zero leakdown servo I was told there was no advantage. I'd say that was good advice. Some guys with old school injection will taxi into parking with the fuel valve turned to off. I hear it works well for engines that tend to flood when parked.
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  17. #17
    wireweinie's Avatar
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    Quote Originally Posted by stewartb View Post
    Starting old school fuel injection with old school mags must be different than new tech fuel infection with electronic ignition and auto spark plugs. No POH for my Cub and hot starting is a total non-issue. Start it hot just like starting cold. Prime it and crank it. It fires right up.

    I never had any problems hot starting my old Continental IO-360, either. When building this Cub I considered adding a fuel return like Continental uses but with a zero leakdown servo I was told there was no advantage. I'd say that was good advice. Some guys with old school injection will taxi into parking with the fuel valve turned to off. I hear it works well for engines that tend to flood when parked.
    What injection system are you using?

    Web
    Life's tough . . . wear a cup.

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    Airflow Performance 200A. Their most current high performance servo. The zero leak down is big. Guys with the previous iteration were adding a purge valve and a return line to relieve pressure. API told me, okay convinced me, that I didn't need the purge valve. They were correct. Those guys know their fuel injection. I know guys with Silver hawk injection that have had their cylinders fill up with fuel. API says it's possible i could see that as well given the right circumstances. Gravity fed fuel systems always have some fuel pressure. They advised me that high wing FI operators should get in the habit of shutting off the fuel when shutting down the engine. So far I never have.
    Last edited by stewartb; 08-09-2019 at 09:43 AM.
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  19. #19
    hotrod180's Avatar
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    Quote Originally Posted by mvivion View Post
    There are no Lycoming IO 360 engines in Cessna 185s. The 185 has a Continental fuel injection system, with a return line. And none of the 185s I’ve flown had fuel shutoff wired shut. BTW, the fuel selector was an option on at least early 185s. MTV
    FWIW here's a pic of the fuel selector & fuel cutoff arrangement in a friend's C182 with the Air Plains IO550 conversion.
    You can see the cut-off is safetied on.
    Another friend has an IO550 conversion (not sure if it's Air Plains) in his early C180,
    his cutoff is located differently but is also safetied.
    Seems like I've seen some factory fuel-injected Cessna's with a safetied cutoff also,
    but I can't recall just which model.

    Click image for larger version. 

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    Click image for larger version. 

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    MY 180 with the IO520 conversion from Air-Planes also has the fuel shut-off safety wired. This was added as the original system did not have an OFF as I understand it.
    Remember, These are the Good old Days!

  21. #21
    texmex's Avatar
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    Continentals - Hot start in rich.

    Lycoming - Hot start in ICO.

    Read the manual on hot starts and vapour purging.

    Fly regularly.

    If you have a difficult engine to start I've found it in the ignition rather then the fuel system.

    All above is gross generization of distant experience. Although mostly acquired flying in hot deserts.

    I wish I had better systems knowledge on why the difference between Continentials and Lycomings, but back in the day flying lots of different types I know it works.
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