Hot Start IO-550G

[Mooney217RN]

I need some help from the Mooney community here.  For 20 years, I could hot start my IO-360 in my sleep.  In fact, the hot start was often better than the "cold" starts on that plane.  So for 2 years now I have been flying my new Ovation, and loving every moment of it.  Spare hot starts, which I do periodically.  I have tried every single method I have read, with no luck.  The best I have found is to prime the engine with the low boost, retard the throttle a bit, crank it and move the throttle full open until the engine ignites, then retard the throttle to normal idle RPM.

If anyone has a better technique, I would appreciate hearing about it.

[Jeff_S]

It sounds like you are doing a version of the Deakin technique, assuming you are priming the engine with the mixture at cut-off and running the pump for a minute or so.  That is a pretty good technique.  What I have found to work is to go full throttle, fuel pump just a skosh to see the fuel pressure go up, throttle back out and then turn five times, then crank.  I can tell by the way the engine is cranking whether it is flooded or needs more fuel, so depending on the situation I may turn the pump back on or just let it go until it fires.  The trick is to get enough cool fuel in the line to reduce any vapor barriers but not too much to throw off the fuel/air ratio.  That's why opening the throttle more than on a regular start can help compensate if you've got too much fuel in the lines.

It is an art, for sure.  The pure Deakin technique claims to have it down to a science, but I've tried it and found that it isn't foolproof either.  My technique works for my engine pretty well, with little risk of backfiring flooding.  But each engine does seem to do it's own thing.  Just remember your basics: fuel/air/spark.  You have to find the combination that will work reliably for your engine.

[M20S Driver]

I used many procedures and the one that works the best for me is the one in the POH:

Throttle at Idle

Mixture full rich

Low Boost ON and Start immediately. 

Advance the Throttle slowly after a few blades and if all the way in, pull back to idle slowly.

[GeeBee]

I start just like I cold start. I NEVER leave the boost pump on after priming hot or cold. To prime I have mixture full rich, advance the throttle to 10gph, then idle. Boost pump off. If I cold start it fires right up. Hot start I advance the throttle until the air flows matches the fuel in the cylinders and she lights right up, usually at about half throttle and about 5 blades, then quickly down to idle. Works great.

 

[Mooney217RN]

I have tried a variant of the technique in the POH.  I have the throttle cracked a bit, low boost pump to prime, shut off the pump, crank and advance the throttle until the engine starts.  Do you leave the low boost on while cranking?

 

I have tried the "Deakin" technique, no joy on that one either.  The theory on clearing the fuel pump/lines of vapor is good.  But it just doesn't seem to work either.

[Missile=Awesome]

Run the boost pump for a full minute with the mixture at idle cutoff.  Boost pump on crank and boost pump immediately OFF with engine start.  Works great for a HOT start.  Otherwise. Boost pump on 2-5 seconds if engine cold and crank with mixture in.  Boost pump immediately OFF when engine fires.

Works great for me.  Flooded start. Full throttle mixture out.  Slowly push mixture.  When fires throttle immediately retard mixture in.

[StevenL757]

1 hour ago, Mooney217RN said:

I need some help from the Mooney community here.  For 20 years, I could hot start my IO-360 in my sleep.  In fact, the hot start was often better than the "cold" starts on that plane.  So for 2 years now I have been flying my new Ovation, and loving every moment of it.  Spare hot starts, which I do periodically.  I have tried every single method I have read, with no luck.  The best I have found is to prime the engine with the low boost, retard the throttle a bit, crank it and move the throttle full open until the engine ignites, then retard the throttle to normal idle RPM.

If anyone has a better technique, I would appreciate hearing about it.

This works every time...at least for the IO550N:

• Throttle full open, mixture cutoff
• High boost 3 to 5 seconds, then off
• Retard throttle to about 7 full "twists" on a vernier throttle (1/4" open approximately)
• Crank engine while slowly pushing in mixture until engine catches (usually 5 to 7 blades)
• Retard throttle to flight idle (~1000RPM) as soon as practical

Steve

[Mooney217RN]

Just so everyone knows, I have no issue with cold starts.  That's a simple one.

 

StevenL757 - I haven't heard of that technique yet.  Might be a winner.

[Niko182]

Mine is:

• Throttle full open, mixture rich
• High boost 1 to 2 seconds, then off
• Mixture full rich
• Crank engine while slowly pulling throttle to idle
• It catches when the throttle gets to the halfway point nearly every time.

 

[StevenL757]

4 minutes ago, Mooney217RN said:

Just so everyone knows, I have no issue with cold starts.  That's a simple one.

StevenL757 - I haven't heard of that technique yet.  Might be a winner.

It is.  Worked for years on my IO550G before that engine was replaced in 2014.  No backfires ever.

[Mooney217RN]

2 hours ago, StevenL757 said:

It is.  Worked for years on my IO550G before that engine was replaced in 2014.  No backfires ever.

I have printed it and will place it in the aircraft reference guide for trial use.  Many thanks!

[hypertech]

What seems to work for me is to just crank it and bump the fuel pump once it fires.  If that doesn't work, I follow the procedure in the POH.

[Cruiser]

This is what the Continental reps claim is the best method for hot starts...............

1. Don't touch the power leave it where it was at shut down

2. Mixture - full rich

3. Start. The engine will fire in just a couple of rotations, 

4. IF the mechanical fuel pump does not keep the engine running, add Low boost pump

5. When engine is assured to keep running turn off Low boost pump. (should only be a few seconds. ) 

Always works. 

This method reduces the risk of flooding, high RPM and long cranking time.

[hypertech]

^ sounds like the "just crank it" method I used but phrased much more elegantly.

[kmyfm20s]

4 hours ago, Niko182 said:

Mine is:

• Throttle full open, mixture rich
• High boost 1 to 2 seconds, then off
• Mixture full rich
• Crank engine while slowly pulling throttle to idle
• It catches when the throttle gets to the halfway point nearly every time.

 

I do the same technique and it has always worked. I leave the throttle full and wait until I here the engine catch then pull the it straight to idle. The first few times you do it the engine will rev until you get the hang of the throttle. Keep your brakes on:) The only time it doesn’t work is if I don’t prime enough. This is basically the same as a flooded engine start.

[Jim F]

As some background, I used to work for a major engine overhauler and I would do first engine runs after overhaul and that includes set up of the fuel injection system.  With setting of fuel flows hot starts are the norm. 

This is very close to Niko 182 procedure.

This is what I use then and now on my Continental TSIO-360-GB. This process starts with the throttle wide open, you MUST keep your hand on the throttle to pull back immediately once the engine starts.  Full throttle, mixture rich, low boost for 2 seconds(this clears out the fuel vapor in the fuel lines), crank, engine will start when the fuel/air mixture gets right, pull the throttle back to 1000rpm.  

For a Lycoming injected engine hot start: full throttle, mixture rich, boost for 3 seconds, mixture idle-cutoff, crank, once the engine starts bring in half the mixture and throttle back to keep rpm below 1300 as the engine roughness clears bring in the rest of the mixture.  There is a lot going on here so you need to be on the ball.  

Jim

 

[carusoam]

What makes the IO550 different than the Lycomings... the fuel delivery system is significantly different...
 

We have more instrumentation than the POH even makes reference to... certainly, the procedure was written by Continental, but not specifically for Continentals in Mooneys...

Things to consider...

1) hot starts barely exist for the Ovation...  as in, The engine doesn’t usually Get so hot and stay that way for long...

2) When it does, you can hear the fuel boiling while you stand next to the cowl...

3) If you hear boiling, this is the reason for the first half of the hot start technique...

4) use the mixture at ICO, and pump fuel through the system, back to the tank...  The POH procedure is really good for this...

5) vapor in the line causes too much fuel to push forwards... followed by the bubbles occupy space in the lines... they get delivered, but not as much fuel gets to the injectors when Bubbles are coming in...
 

then...

6) The hot engine evaporates lots of fuel, that the cold engine won’t...

7) If, you have skipped cooling the lines... you may want to run the fuel pump to allow a minimum amount of fuel to fill the lines...
8) by the time the FF indicator starts showing data... that’s the hint the lines have fuel in them...

9) Getting the FF to register only takes a second or two...

 

So...
 

10) use your FF instrument to know when the lines are full...
 

11) use your knowledge of the plumbing system to know how to get fuel to circulate...

12) Eliminate the confusing variation...

13) To move fuel around, throttle at WOT works best... it changes with throttle position...

14) ICO sends fuel back to the tank you have selected... (not true for all IO550s)

 

Fun details...

15) Ovations have a twist throttle... two full twists will deliver enough air to start the engine, as it fires up it will exceed 1k rpm... 1.5 full twists will be close to 1k rpm, 1.0 twists will probably be two low... Be ready to untwist a turn...

16) running the fuel pump and the starter is definitely a way to get too much fuel when it is hot...

17) running the fuel pump, and continuing after the start... is normal for really cold days...

Summary...

18) The biggest challenge is to understand how much fuel vapor is getting to the cylinders...

19) The Hot engine challenge is avoiding vapor in the fuel lines...  randomness of bubbles in the lines

20) the heated engine easily evaporates fuel... use the minimum amount of prime
 

21) The biggest source of randomness... is the time required for fuel to arrive at the FF sensor...   I  use time, after the FF comes alive...

 

When picking logical routes of IO550 operation... I follow Steven’s guidance... he has way better memory than I have... and enjoys the IO550 technology...   

The most important thing to do while experimenting or during engine start...

REMEMBER to pull the throttle back, after circulating and priming... 

Best regards,

-a-

Anything in this list a surprise, or not understood?

PP thoughts only, not a Mooney specific CFI...

Best regards,

-a-

 

[Mufflerbearing]

The single best thing I have done to make hot starts better was installing Tempest Fine Wire plugs top and bottom.  Starting is so much easier!

[Mooney217RN]

Thank you, everyone, for all your excellent suggestions.  I have printed each one, and placed the sheet in my flight bag.  I will report back on my next hot start.  I like Mufflerberaing's suggestion too with using fine wire plugs, but at this point, I will try the various techniques as a primary course of action.

 

Hot starts always make me nervous, as I wonder if the engine will ignite :-(

[Mooney217RN]

On 10/5/2020 at 3:12 PM, Cruiser said:

This is what the Continental reps claim is the best method for hot starts...............

1. Don't touch the power leave it where it was at shut down

2. Mixture - full rich

3. Start. The engine will fire in just a couple of rotations, 

4. IF the mechanical fuel pump does not keep the engine running, add Low boost pump

5. When engine is assured to keep running turn off Low boost pump. (should only be a few seconds. ) 

Always works. 

This method reduces the risk of flooding, high RPM and long cranking time.

WINNER WINNER, CHICKEN DINNER!  WE HAVE A WINNER - 

 

I just tried this method, ever so slightly modified.  As the engine stumbled a bit on startup, I added power to keep it running, very brief throttle increase.

 

Cruiser, thank you SO much!  I will try the other methods on other occasions.  I randomly selected this one.  This worked FANTASTIC!

[philiplane]

Leave the oil filler door open after shut down. Heat now has a direct exit from the engine. Hot start problem goes away.

[Mooney217RN]

1 minute ago, philiplane said:

Leave the oil filler door open after shut down. Heat now has a direct exit from the engine. Hot start problem goes away.

I've done that before, it helps, but doesn't solve the problem.

[philiplane]

How many hours on the magnetos? 

Install fine wire Tempest plugs if you don't have them already.

[r0ckst4r]

So I literally logged in in today to post about this very predicament!   I follow the POH methods to a "T" and always had difficulty with a warm or hot starts, usually after a fuel stop.  I ended up playing with the throttle like some have suggested which got the engine going but never had it down to a fine science.  Glad to see a lot of good information and I'll have some new techniques to test out for next time!

[Mooney217RN]

23 hours ago, r0ckst4r said:

So I literally logged in in today to post about this very predicament!   I follow the POH methods to a "T" and always had difficulty with a warm or hot starts, usually after a fuel stop.  I ended up playing with the throttle like some have suggested which got the engine going but never had it down to a fine science.  Glad to see a lot of good information and I'll have some new techniques to test out for next time!

There's a wealth of information here.  I figured that others were challenged by this besides me.  Read "Cruiser's" technique above.  It worked perfectly for me, twice.

I am also opting to switch out my plugs next time I do an oil change to fine wire plugs.  My plugs have about 200 hrs on them, so I will have no regrets over removing them at 225 and replacing them.  Generally speaking, the mass electrode plugs only last 250-300 hrs in these engines.