Help me Hot Starts Fuel Injection

[kjmorris2023]

Fly a converted Varga Tail Dragger. Engine I think originally came out of a Grumman Cheetah E2G version of lycoming. Now after an overhaul they added the fuel injection with Bendix Fuel injection system. It's 160Hp. Has a inverted oil system as well as added fuel tank if desire is there to fly inverted. Partner says the sytem is about identical to what you see in a Decathlon. Anyway probably a lot of useless info but can someone help me with techniques for hot starting this beast. Cold starts are of course easy. It has a fuel boost pump as well as mixture control. The partners have given me some techniques but they don't seem to work well for me? I'm afraid to take it out for bfast with the wife because invariably I'll have great difficulty starting it on the return leg. Thanks a bunch.

Ken Morris

[rv969wf]

Hi Ken,
Your going to hear many techniques from a lot of people on here BTW. This is what works for my FI Bendix / Lyco for starting hot.

What I do is set the throttle at idle, mixture full rich, run the boost pump about 2-3 seconds to purge the lines and to make sure there is not vapors or air in the lines. Then I pull the mixture to shutoff, set the throttle Wide open throttle, crank the engine over and when it starts to fire feed the mixture in slowly while pulling the throttle back to idle. This may not work for every application but it seems to work on my engine. What I've found out on my engine is if I don't purge the fuel injection lines with raw liquid fuel, it will never start. You do not want to flood the engine, but it takes a little of trying this and that. You might try running the boost pump for a second or two and watch until you see fuel pressure or it might take 3-4 seconds. Hope this helps and I know that every bird is different. This works for me but it might not for someone else. Good luck as I'm sure your going to get every answer in the world.

PS, they do make a purge valve that is cable operated to direct fuel from the spider on top of the engine back to the tanks, this will purge the lines without fuel being fed to the injectors. What this does is purge any boiled fuel out of all of the lines except the small lines to the injectors. This helps to cool down the fuel pump, bendix, etc so there will not be any boiled fuel in any of the lines except the small lines to the injectors. After this is done, the boost pump is used to prime the engine. I don't like this system because there is just one more thing to go wrong and direct fuel back to the tanks and not the engine.

[mahlon_r]

This is what I use:

Procedure for a cold engine:

(1) Set propeller governor control in "Full RPM" position (where

applicable).

(2) Turn fuel valve "On".

(3) Open throttle wide open, move mixture control to "Full Rich"

turn boost pump on, approximately 3 to 5 seconds, turn boost pump off,

then return throttle to "Closed" and return mixture control to

"Idle Cut-Off".

(4) Open throttle 1/4 to 1/2 of travel. Keep you hand on the throttle during the staring process to make movement toward the idle position after the engine has started an easy immediate thing to be able to do.

(4) Set magneto selector switch (consult airframe manufacturer's

handbook for correct position).

(5) Engage starter.

(6) Engine starts.

(7) Retard throttle towards idle position.

(8) Move mixture control slowly and smoothly to "Full Rich".

(9) Check oil pressure gage. If minimum oil pressure is not indicated

within thirty seconds, stop engine and determine trouble.





Procedure for a hot engine that was shut down with in a few minutes ago:

(1) Set propeller governor control in "Full RPM" position (where

applicable).

(2) Turn fuel valve "On".

(3) Open throttle wide open, move mixture control to "Full Rich"

return throttle to "Closed" and return mixture control to

"Idle Cut-Off".

(4) Open throttle 1/4 to 1/2 of travel. Keep you hand on the throttle during the staring process to make movement toward the idle position after the engine has started an easy immediate thing to be able to do.

(4) Set magneto selector switch (consult airframe manufacturer's

handbook for correct position).

(5) Engage starter.

(6) Engine starts.

(7) Retard throttle towards idle position.

(8) Move mixture control slowly and smoothly to "Full Rich".

(9) Check oil pressure gage. If minimum oil pressure is not indicated

within thirty seconds, stop engine and determine trouble.



Procedure for a hot engine that was shut down more than a couple of minutes ago:

(1) Set propeller governor control in "Full RPM" position (where

applicable).

(2) Turn fuel valve "On".

(3) Open throttle wide open, move mixture control to "Full Rich"

turn boost pump on, approximately 1 second or less, turn boost pump off,

then return throttle to "Closed" and return mixture control to

"Idle Cut-Off".

(4) Open throttle 1/4 to 1/2 of travel. Keep you hand on the throttle during the staring process to make movement toward the idle position after the engine has started an easy immediate thing to be able to do.

(4) Set magneto selector switch (consult airframe manufacturer's

handbook for correct position).

(5) Engage starter.

(6) Engine starts.

(7) Retard throttle towards idle position.

(8) Move mixture control slowly and smoothly to "Full Rich".

(9) Check oil pressure gage. If minimum oil pressure is not indicated

within thirty seconds, stop engine and determine trouble.

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."

[grjtucson]

Ken,

I have a '77 Decathalon with an AEIO-320 down here in Tucson. Hot starts for me are as follows:

1. Mixture rich
2. 1 second shot with boost pump
3. Mixture full lean
4. Throttle on high idle (1/3 +/-)
5. Crank and when she catches, mixture to ground idle, then throttle to normal idle. Normally doesn't take more than 3-4 blades.

Note: I never use full rich in this plane, our plugs load up really quickly. Ground and taxi idle is several clicks richer than cruise. I go a few more clicks than that for takeoff and climb, then lean for cruise at altitude. Back to richer (like takeoff/climb) for landing or pattern work, just not full.

No EGT, fuel flow, or CHT in this bird.

I fly out of 2400' field where DA is never that low Even at sea level I haven't used full rich with this engine, just the same technique as above, though the knob was further in.

All this said, I'm told that every engine has a preference, probably every pilot too. You may have to try a bunch of different approaches to find one that suits you and your plane.

George

[hevansrv7a]

http://www.aopa.org/members/files/pi...0/anp0007.html

[aadamson]

Opinion, opinions, opinions... ...

Let's see, they are "all like armpits, and they all ...." well, you know the rest of this... Actually, there are some good comments here and you'll need to see which of these will work with your engine.

However, in the last 2 airplanes that I've owned and the one that i'm currently flying, the following has worked "every time", ok almost.

HOT START ONLY!
- Mixture full lean
- throttle full closed
- bump fuel pump to do nothing more than "pressure the lines" then off, maybe 1 second on/off
- open throttle 1/4"
- crank over engine to start
- at catch, mixture to full rich

I used to have the hardest time starting HOT. I dreaded it until I learned the above. Now it's no big deal and I'd say I'm about 96% with the above.

Ok, now a couple of comments on the other procedures. IT WILL VARY IF YOUR ENGINE IS A LYC VS. A CONT.

Most, not all conts, have a return line on the fuel system. Most, not all Lyc don't. This means trying to do any "purge" will only work on those with return lines. Purging on one without a return line, especially if the throttle is open is doing nothing more than putting raw fuel into the cylinders (something you are trying not to do on a hot start).

Here's the other trick to all start procedures.... The Second, and I mean the second that your have the engine turning over, grab that big red knob and pull it out an inch or more. In fact, find the spot where if you turn it 1/4-1/2 turn more the engine will quit and then set it at the 1/4" from there spot. leave it that way until mag check and then back to that spot until take off.

Don't worry about take off, you'll know to fix it just fine as the second you add power, the engine will just about stop and you'll realized and fix the mixture.

Do the above as soon as you land as well. All of this will limit the effects of vapor development on the ground, and will also help with no lead fouling. Your engine will like you lots better and you'll be a happy pilot.

So there you have it, yet another opinion ...

[kjmorris2023]

George,

When you say full lean you mean all the way back to cut-off correct. Thanks for your help.

Ken Morris

[kjmorris2023]

Thanks, I'll try it soon.

[kjmorris2023]

Thanks for your detail. Appreciate it.

Ken Morris

[osxuser]

I'm not into moving knobs all around when I don't have to, so here is my two procedures. Both work fine for all Contiental and Lycoming engines I've started (and thats quite a few):

Cold:

Fuel Valve on
Master on
Mixture full rich
Throttle 1/2
Pump 3-4sec or until Pressure/flow indication
Pump off
Throttle cracked 1/2"
Crank until firing
Mixture lean for taxi (1" lean)

Hot:
Fuel Valve on
Master on
Mixture ICO (Idle Cutoff)
Throttle 1/2
Crank until firing
Slowly add mixture to 1/2
Retard throttle to idle
Add remaining mixture to lean taxi (1" lean)

Always works for me. Less knob moving that other methods. The hard part is swaping the posisitons of the throttle/mixture during the hot start, but it works fine.