Hot Starts

I have a lot of experience with all things not injected. But the last four years with the Super D, I have discovered that I simply do not know what is really happening up there.

So far (knock on wood) she has always started hot, usually after I am sure I am spending the night right there. After 15 blades, she catches, then all the words and levers I have do not keep her going. Then another attempt. Often the "flood it, then starve it" routine works, but not without another anxiety attack by the guy strapped in -

The strange thing is, each engine seems to be just a bit different - jam the mixture in too quick and one will quit. Jam it in too slowly and another will quit. Yesterday I discovered that a hot start at 8000' density altitude still requires full rich to keep it going.

I'll tell you - if I was drifting in a seaplane while trying all this, I would be getting lots grayer lots quicker.

Sure - I should ask this on a forum where Decathlons are discussed, but you see, that forum is not visited by very many folks from year to year. You, my friends, probably have the most knowledge of such subjects.

I solicit your opinions and hints.

I hot start the worst of the worst one to two times a week. What happens with the lycoming Injected engines is the gas boil and vaporizes in the spider lines making hot starts very hard to predict. I use a technique for ten minutes later, thirty minutes later and then the guaranteed flood start which I prefer the best for anything after a short shutdown.

Firewall forward, positive fuel flow then count one two, pump off. Two benefits, lowers the compression and takes the guess work out of the fuel air mixture ratio control,when she's ready she fires. Also guarantees you have cold fresh gas ready in the system ready to stay running which is part of the problem with hot starting all injected engines.

Mixture lean,full throttle and let her rip. Works 100% if the time with the IO 720.

I think the 180 HP injected is about as tricky as the 720. Seems you have the hot flooded starts down. I really think that full throttle and cool gas is the ticket.

I have saved many of IO 540 drivers on the ramp with a near dead battery.

Fine tuning the hot start takes practice, sometimes it's a shot of fuel pump with balls the walls and then full lean and quarter throttle.

With the IO 320 B1A I seemed to remember a shot of gas with the mixture rich then lean, then spin with quarter throttle -fire off -mixture rich and reduce throttle. I also remember not jaming in to quick for some reason, kind of nursed in as required. Who knows. I like the flood start because she hits about the 8 to 12 blades every time. I had zio 320's down to science after 500 hours but its been some time for those. A twin Comanche driver that knows his airplane and has flown it for 10 years would be the best source. Go to the International Comanche Society for that. One last thing. Flood less and less each time. only enough so that the engine spins differently. They finally put a by pass dump valve in the 400 so that you could prime the system hot without flooding it. It helps alot. Hope this helps.

I fly IO320B1A's in my Twin Comanche. If the engine is hot, throttle full forward, mixture idle cutoff. Engage starter. At the same time, slowly pull throttle back towards idle. When the air/fuel mixture is right it will light right off, mixture towards rich at that point in time. Continue the throttle pull back and it will start without ever "over-revving" and disturbing whomever or whatever is behind you. HTH.
JG

Throttle all the way back, no prime, put right front in front of right tire, left foot behind tire. Reach up and turn mags on, grap prop and pull down. Starts first time on my J-3.

- Full throttle, Mixture Rich, hit the boost pump until it changes tone. turn off after 1-2 seconds. (indicates fuel pressure and no vapor like 46/12 said. You don't want to pump fuel, just get rid of the vapor.)
- Crack the throttle double the normal, mixture idle cutoff. (if 1/4 inch is a normal start, use 1/2 inch)
- Start cranking and it should catch in 5-10 seconds.
- Once it comes to life and starts popping etc... slowly push the mixture in and bring the power to idle. (It will run for about 5 seconds with the mixture out, so don't feel rushed.)

Some people like to start cranking with full throttle and slowly pull the throttle back until it catches. And others like half throttle or some other amount.

The key is pumping enough air into the cylinders to make the fuel/air mixture correct. More throttle equals less cranking.

Personally I'd rather have a starter fail just a little earlier, instead of letting the engine come to life at 1800 rpm. Plus I had the tail come up when using the 'Retarding Full throttle' technique.

nkh

Ya what he said.

Thanks. I am going to print this stuff. I am guessing the key is the hot vaporized fuel in the lines above the engine.