Hot engine starting

Recently purchased SR20 with Continental IO 360 E. The aircraft first start of the day is usual after second attempt however all further starts take 4-5 attempts and at this rate I’ll soon need a starter as well. I just had mag rebuilt/overhauled and timed and during runup mag check is well with in tolerance.

Do others have this problem? Are there any special procedures out there?

Thanks!

Most Fuel Injected planes can be a PITA to start once they are warmed up. Certainly using the check list procedure for a normal start tends to flood the engine as it is now longer cold and does not need much fuel to run. Once you learn what your engine likes, its not so tough.

I fly a 22, so what I do may or may not help you in your 20. I run the boost pump with the MIXTURE CLOSED (so you don’t flood the engine) for a little while - perhaps 30 secs. That runs cool fuel through the lines (returning it to the tank because the mixture is closed) and reduces the vapor lock that has developed. Then I open the mixture knob for a brief sec or two (pump still on boost) to allow a small amount of fuel to go to the cylinders. DO NOT USE PRIME - for a warm engine that is just way too much fuel. Then I hit the starter and rock the power lever just a bit. If that doesn’t do it (usually does) I open the power lever all the way. Lean it aggressively once its started. I find once it starts it does not want to run real smooth for a moment, so I keep my hand on the throttle and will gently rock it forward and back until the engine can run without a fuss… Don’t shut the boost pump down until leveled off in cruise, that helps cool the line with a bit extra volume until established in cruise.

YMMV, good luck.

Cliff:

The following advice as well as the warning are from Mike Radomsky from some while back.

The easiest way to guarantee an easy hot start is to leave the mixture control alone on shut down. Just kill the engine with the mag switch. Leave the mixture control whereever it was before the shutdown.

On restart, just turn on the boost pump and note fuel pressure and hit the starter. It should start instantally.

Here is the hazard: You are leaving the plane in a potentially dangerous situation. The hazard is that somehow the ground connection to the two mags that was made when you shut off the ignition switch might somehow fail and someone could then pull the prop and get the engine to start.

As a result, this technique is only usable where the plane is going to be left in a relatively secure location, hopefully where you can keep an eye on it.

You do know that the ground connection to each mag was good when you shut off the engine, since when you turned off the ignition it stopped.

I find that the old habit of pulling the mixture control at shutdown can be very hard to break and sometimes I pull the mixture when I know that there will be a hot start in the near future.

A few additional points:

(1) I have an SR22 with the IO550. However, both engines are fuel injected and both share the same problem. When a fuel injected engine is stopped by pulling the mixture, all of the fuel that was in the plumbing from the mixture valve on is gone and has to be replaced before the engine will start.

(2) There are other techniques as described in this thread. However, the one that is dead simple is to just shut down with ignition and leave the fuel alone.

(3) It is possible from engine heat to radiate inside the cowling to the point where the fuel in the suction side of the electric pump turns to vapor. If the day is really hot where the ramp is just radiating heat and you are at a relatively high altitude (>1000’ even) that fuel may vaporize. In that case the electric pump won’t pump and the techniques described about running the electric pump won’t help.

Here is what to do to fix the vapor where the electric fuel pump won’t pump: (a) Take the keys, put them in your pocket (b) get your fuel sampler © station someone at the fuel pump switch (d) get to the gascolator under the engine (e) get that person to hit the “prime” switch (f) keep taking samples until you get liquid fuel in the sampler. You will probably hear the pitch of the electric pump go lower when the liquid fuel gets to it.

Here is what to do to avoid the problem to begin with: (a) park facing the wind if possible (b) right after shutdown open the oil filler door. You will probably feel the stream of very hot air exit the cowling. With air circulating through the cowling, the tendency of the engine to heat the fuel lines to the point of vapor will be less and you will probably avoid the problem. If not, see above for the fix.

Finally, don’t overheat the starter. I can’t remember what the POH says on the starter use, but follow that. Let it cool between attempts. If you follow the shut down by ignition technique, you won’t have a hot starter problem.

Cliff I have a 22 supercharge and before it was installed I always shut it down by leaning it then I would turn boost on for 30sec, turn to full rich, power to almost lowest setting turn key as it started roll power on just a bit more works every time with SC works the same just a little higher power setting

Ricky:

What you describe is my cold start technique. For some reason in my NA SR22 if I do the same for a hot start, it will be a long time starting. For some reason there is something different in starting a cold engine and a hot one. With a cold engine that has been shut down by the mixture (which I always do if the engine will not be run for >2 hours) boost pump full rich mixture and low setting on power lever works instantly.

When the engine is hot the same technique does not work. If fuel is left in the lines and the engine is shut down with with the ignition switch it will start instantly with just boost pump just prior to start.

The technique I described of draining fuel from the gascolator is not needed unless it is a really hot start and you don’t see fuel pressure when the electric pump is turned on. Since I started leaving the oil filler door open on hot ramps I have not had to use the technique since the heat from under the cowling escaped through the open oil filler door.

Steve,

Do you have the SB installed that changes the prime disconnect feature? It is SB22-73-01. It made a huge difference in my cold start procedure. From 30 - 45 seconds of prime to 2 or 3 secs. Planes after SN 277 had it from the factory, if yours is earlier than that and you have not had it done you might consider it. Its description from CDC is:

Boost pump operation is currently controlled by the fuel pressure switch during initial engine start-up. After

approximately 5 seconds the fuel pressure switch sets the boost pump to low pressure. After installation of

the Improved Starting Circuit Kit, holding the fuel pump BOOST - PRIME switch in the PRIME position will

allow high pressure fuel pump operation until the oil pressure light turns off.

Roger:

This was done years ago. Yes, it made a huge difference. I used to have to “bump” the prime switch to get enough fuel in the lines.

But, this thread is not about cold starts.

The issue with hot starts is that there is not enough fuel in the lines and somehow fuel entering a hot fuel line reacts differently than fuel entering a cool fuel line. I am not sure exactly what is going on with the hot engine after it has been shut down with the mixture control. It is possible that some of the fuel entering a hot line vaporizes and prevents more fuel from flowing on. The result is a lot of cranking without a start.

The easiest solution I have found is to shut down with the ignition switch and leave the mixture control alone. Whenever I do that all it takes is turn on boost pump (no prime needed), hit the starter and it starts right away.

The continuing problem is that I have become so acustomed to shutting down with the mixture control that it takes a special thought “I’m going to shut down with the ignition switch” to remember not to pull the mixture control. Whenever i do shut down with the ignition switch, the start is literally one blade and it’s firing.

Sorry, I misunderstood your post. You and I do almost exactly the same thing. I also kill the engine iwth the ignition switch for quick turns and have the same tendancy to grab the mixture out of habit. As a result if I used the red handle, well then I have to use my “other” hot start procedure [;)]

OTOH, I never have had to do the procedure with the sample cup you mentioned and I live in Phoenix.

WoW! Thanks to all for all the responses. I had this same problem with a Lycoming eng and found a procedure that eventually worked.

Again, Thanks ALL

\

Cliff,

If you were pleased with the responses you got here, had you posted on the Member’s Side you would have gotten 3X as many!

I

This technique will work everytime. I have started engines after landing and refueling when it was 110F outside.

  1. full throttle full mix like normal.

  2. high boost/prime till you get 10 on the fuel flow like normal.

  3. low boost, full throttle, mix idle cut off.

  4. crank engine and slowly add in mixture. As engine catches go full rich and bring the throttle back to normal setting.

Just a comment for some posts above. Watch out with the priming for long periods of time even with the mix at cutoff because the fuel will spray out under the belly of the plane and could cause a bad situation. Next time you prime for a long period look on the ground under the cowl.

Mark W

At high altitude (Leadville, Aspen) this may or may not be sufficient. It was at Leadville but not Aspen. The next step is a painful one but it works. Remove the vent cover on the tank that is selected. Then remove the vent line. One person blows into the vent line to pressurize the tank while a second person sumps the gas collator and a third person turns on prime and waits for it to “grab.” Once primed then it will take awhile to reassemble the plane but the engine will start and the pump, now with fuel and not vapor, will work. This is a painful process but effective. Because of my experience with this (on an older Airshares plane) I had [url=http://servicecenters.cirrusdesign.com/techpubs/pdf/SB/SR2XBulletins/SB2X-28-05R2/SB2X-28-05R2.pdf]this[/uel] hot start SB done when I got my plane.

Paul

Paul,

Seems like you could just sit in the FBO with a nice cold Coke and visualize doing all those steps. By the time you actually did all that, the plane would probably be cool enough for a “normal” start! [:)]

Paul:

I could not make the link work. Are you talking about the SB that has the boost switch circuit run through the oil pressure switch? I had this SB done many years ago. This has been very helpful, since the fuel pump will run without limitation so long as there is no oil pressure.

I have never had a problem that I could not fix with my technique. In fact, by leaving the oil filler door open in very hot conditions, I have never had to even do that technique. Leaving that door open lets a large amount of hot air out from under the cowling. The only time I had to go to the length of taking the samples from the gascolator was when I did not leave the oil filler door open.

I’m too lazy to read through the responses, most have some amount of truth in them. Being a COPA member you’d get the entire truth. So hot start procedure for the SR-20 to make your life easy:
Mixture full rich
Throttle IDLE - not even cracked.
Fuel pump to BOOST - not PRIME
While in boost mode listen for the sound of the pump to change. When it reaches a steady tone, then you have purged the air from the lines. If it seems ‘wobbly’ then keep it on boost until the sound becomes a uniform moan.
When you have a uniform moan, turn the boost off. Throttle 1/4 inch - NO BOOST PUMP
Start. Should turn in 3 blades.
Life is good.

Sorry. Maybe I did something wrong. Go to the Cirrus website and put in your serial number. It is under “Fuel” and is listed as:

SB2X-28-05R2
Hot Climate Start
18 Sep 2006
Revision 2
Optional
SR22: 0002 thru 2042
This prevents fuel that vaporizes in the lines from pushing fuel back into the tanks.

Paul

I pretty much do what Roger suggested. throttle open, mixture off, run boost pump on PRIME for about 20 seconds and at least until you I see fuel flow on the flow gauge. I don’t know if the new planes have an analog gauge. Mine’s a 22. Then throttle just cracked open, mixture rich, boost pump on and crank. The whole key is to run fuel through the lines but not into the engine.

Oops, I think I meant throttle closed, mixture full rich.

First, to All Thanks for your great feed back and suggestions but after trying a number of variations still no luck. Took the aircraft to my local mech who checked timing and mags and found the timing off 6 deg and gap slightly to large. A little disappointed since it just came out of annual/mags overhauled/timing.

Since his adjustments all is GREAT! Starts Hot/Cold no problems.

Again, Thanks!

Cliff

Ditto for me on the not reading the other posts. I now have a method that works every time and I am not going to pollute my mind with ideas that might lead me to mess up my starter again. About two months into ownership I read a “surefire” method for hot starts on COPA that was just plain wrong and I burned out the starter in Montana the next day. Did not find out about the dead starter until after I landed in Valentine, Nebraska. A nice old guy hand cranked it for me so I could get to Lincoln for repairs. I do have to say that this is the only time I ever got significantly misled by anything on COPA. You need to join.

By the way I have an IO 360 ES SR20 also.

Shut down your engine the traditional way with the mixture. On restart, go full open throttle and full lean mixture. Prime well, until the sound changes and then another couple of seconds. Boost on. Wait 10 seconds or so. Start. Wait until engine kicks a little, move the mixture smoothly ahead until it starts well then and only then pull back on the throttle. You will over-rev a little probably before you get the RPMs down with the throttle.

If the engine does not start because you moved the mixture too fast or too slow, wait a full minute and do it again. On occasion I have bumped the prime a time or two when cranking.

If you get no response at all with the first crank after 10 seconds or so, STOP, wait a full minute and do it all again. 10 seconds at a time is the absolute max for the starter.

I have never had to do this but my next step would be to drain the gascolater and do it all again.