jimboflying
MEMBER
Why are fuel injected engines difficult to start when hot?
What is the best technique to use for hot starts?
What is the best technique to use for hot starts?
Then wide open throttle.. and crank.
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.
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.Why are fuel injected engines difficult to start when hot?
What is the best technique to use for hot starts?
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.I was running for my fire extinguishers reading that....
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 )
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.
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
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