Start up procedures
 

I have an fuel injected

Cold start or hot start?

Fuel injected start up problem
 

Sorry, my original post was not complete due to my computer problem.

This is for cold start.

My engine starts rough and ejects black smoke on start up. I have tried some different processes but seem to have difficulty. My usual start up process is the following:

c) Set Prop Control ? LOW PITCH --FULL IN Position
d) Throttle ? OPEN TO ? TRAVEL
e) Master switch -- ON
f) Fuel Boost Pump ? ON
g) Mixture ? Full RICH
h) Ignition Switch -- START
i) Throttle ? AFT TO IDLE SPEED
j) Fuel Boost Pump -- OFF
k) Oil Pressure ? CHECK 25 psi @ idle
l) Alt. Field & Avionics ? ON

does anyone have any sugggestions?

I am just learning with my RV8 (33 hours so far) and what seems to work for me is to crack the throttle, and turn on the boost pump and run the mixture too rich for a few seconds, more if the air temp is cold. I always pull the mixture back to cut-off before I start cranking, and richen up the mixture when it fires.

For me, the hot start is just to start cranking without touching the throttle or mixture, with the boost pump off. It usually fires right away, and I add Mixture to keep it running.

Hopefully others will have better ideas, like I said I am just learning:)

Put the mixture full rich and the throttle wide open before turning on the boost pump. Cold start, turn the boost pump on and then off after 3-5 seconds. Hot start turn the boost pump off after 1-2 seconds. After turning the boost pump off, retard the throttle to 1/8-1/4 open and retard the mixture control to the idle cut off position. Engage the starter and don't advance the mixture control back to rich, until after the engine starts.
Good Luck,
Mahlon
"The opinions and information provided in this and all of my posts are hopefully
helpful to you. Please use the information provided responsibly and at your own
risk."

With a cold start, I've learned that if you get the right amount of fuel into the intake manifold, the engine will start on the one or two blades most every time. However that is done doesn't matter. It takes a little experimenting to get it just right.

Hot start needs no prime. Hit the starter and introduce fuel during the crank and it is running. If the engine is half cooled down, about half prime does the trick.

(Think about leaving the alternator on all the time. The unit may last longer. There was quite a long discussion about that some time ago.)

Hard to tell from the above, Carl, but if you only have your throttle open 1/4 and are leaving the boost pump ON for any length of time, you might want to alter that a bit.

As was suggested (and is also outlined in the Lycoming engine manual, surprisingly), try pushing everything forward -- throttle wide open, prop forward and mixture full rich. Turn on your boost pump for a few seconds -- long enough to verify positive, consistent fuel flow, then turn it off. Close the mixture control and then bring the throttle back to 1/8-1/4 and hit the start button. The engine should come to life and, after it starts, gradually feed in mixture and adjust the throttle to idle speed.

If I've made any errors in that description, I'm sure someone will correct me. :D

Aircraft mechanical fuel injection systems work much differently than carbs. Fuel will be flowing anytime there is fuel pressure at the servo and the mixture is not at ICO. The fuel flow will depend on the throttle setting, mixture setting and the amount of air flow, but there will be some fuel flow even with zero air flow.

So, with the above procedure, quite a bit of fuel will have flowed into the engine before the start is attempted, and it will be very rich until all this excess fuel has been consumed by the cylinders.

The procedure recommended by Lycoming, which was described by several other posters, works well for me. At first I wasn't priming the engine quite long enough, and starts were difficult - I ran the battery down more than once. Starts became very good once I started priming about 5 seconds with throttle full and mixture rich.

Carl, What Mahlon said.
 

I may have learned this technique from reading Mahlon posts before. I works very well.

Kent

If it is bucking and spitting black smoke, you are far too rich. For a cold start, the boost pump is only run for a limited time (full rich, throttle open). The boost pump and individual airplane fuel system will dictate what time is required. For example, the -8 I fly requires the boost pump to run just long enough to start moving fuel. This point is indicated when you can hear it "slow down" and takes about 1 second (yes, I said ONE second). Any more prime than this and it is way too rich at start, no matter how cold. My Hiperbipe on the other hand, is more conventional in that it takes about 5 seconds of boost to prime.

Hot starts are more art than anything, but I have yet to meet a Lycoming that needed boost when hot. If it's hot, the technique that works 99.9% of the time is: boost off, mixture in cutoff, crank engine, advance throttle to full, and wait to fire. When it fires, rapidly go to full rich (it will be spooling down at this point, starved for fuel, so you have to "catch" it before the prop stops), as it catches the second time, retard throttle to fast idle. This all takes about 2 seconds from first catch.