Mooney M20F Cold Start

[Htmlkid]

I recently purchased a 1975 Mooney M20F and Im still struggling with cold starts. My current procedure is turn on master, turn on booster pump, throttle forward, mixture to full rich, pull back throttle to 1/4 and pull mixture all the way back, then if she starts mixture full forward. But she almost never starts the first time... so I randomly do the same thing again... Any thoughts on what is wrong? Warm starts are no issue.

[FLYFST]

[quote post="567403" timestamp="1583023737" name="Htmlkid" userid="18373"But she almost never starts the first time... so I randomly do the same thing again... Any thoughts on what is wrong? Warm starts are no issue.

Are you priming long enough? In my 1990 J I let the pump run for ~6 seconds, less I often have to prime again. Much more is not good either as too much priming is bad too. My Goldilocks time is prime for 6 seconds when cold.


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[Htmlkid]

Do you mean let the pump run 6 seconds before I open the throttle or open the throttle for 6 seconds?

[GDGR]

-Mixture and Prop Rich

-Throttle 1/4 open

-master on

-fuel pump for 3-5 seconds (until fuel flow shows)

-crank. Should fire in 3-5 blades. 

[FLYFST]

Do you mean let the pump run 6 seconds before I open the throttle or open the throttle for 6 seconds?

I push the throttle in 1/4 inch, mixture full, run the pump for ~6 seconds, then turn pump off, mixture back to idle, turn the mags switch and push in to start, and start pushing the mixture in slowly at the first sign of ignition.


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[hammdo]

8 minutes ago, GLJA said:

-Mixture and Prop Rich

-Throttle 1/4 open

-master on

-fuel pump for 3-5 seconds (until fuel flow shows)

-crank. Should fire in 3-5 blades. 

I do this with the rental F I fly and it works for me also...

-Don

[ArtVandelay]

-Mixture and Prop Rich
-Throttle 1/4 open
-master on
-fuel pump for 3-5 seconds (until fuel flow shows)
-crank. Should fire in 3-5 blades. 

Im with others, if 6 seconds usually starts 1-2 blades, longer if colder....if 40°, I prime 8-9 seconds.

[carusoam]

Some docs say...

1) 1/4 open...   which can be a bit much when it fires up... be prepared to pull it back...

2) 1/4”... which is more in line with 1k rpm when it fires up...

3) If the throttle is all the way in to get the proper dose of Prime (my IO550 needs FT), remember to pull it back out before start...  

4) Discussing cold starts without mentioning OAT... is a bit goofy... evaporation of 100LL is very dependent on OAT...

5) If you have a FF meter... fuel hasn’t gotten to the engine until the FF meter comes alive...

6) It is good to know if the FF dead time is included in your timing... (mine isn’t... it cuts back on variables...)

7) above 40°F ordinary start, below...cold, below 20°F... 100LL has such a low vapor evaporation rate... pre-heat is almost always required...

8) engines like to be pre-heated below 40°F whether they will start or not...

How does that sound?

PP thoughts only, not a CFI...

Best regards,

-a-

[wishboneash]

I had same issue in my J. Priming longer has definitely helped. From 5s to around 8 or 9s.. Wait 10s before cranking with mixture out and throttle at 1/4".

[carusoam]

+1 for allowing time for fuel to evaporate...  it doesn’t run out the bottom like expected of some planes...

Best regards,

-a-

[Yetti]

1" of thottle

Fuel pump on

Mixture open

Count to 6

Mixture closed

Fuel pump off

Turn key

When pop advance mixture to 1/3

Pull thottle back to between 1100 and 1200

 

 

[RobertGary1]

1 hour ago, GLJA said:

-Mixture and Prop Rich

-Throttle 1/4 open

-master on

-fuel pump for 3-5 seconds (until fuel flow shows)

-crank. Should fire in 3-5 blades. 

That sounds more like the carbureted procedure. With injected your want the mixture at cutoff when cranking. 
 

-Robert 

[GDGR]

1 hour ago, RobertGary1 said:

That sounds more like the carbureted procedure. With injected your want the mixture at cutoff when cranking. 
 

-Robert 

Like, why follow the POH.... especially when it works? 

[RobertGary1]

20 minutes ago, GLJA said:

Like, why follow the POH.... especially when it works? 

Yea that’s more what I’m used to. Mixture idle cut off before cranking. Pretty much all injected engines say that. 
 

-Robert 

[drapo]

6. Throttle —Open 1/4 Travel.

Some get confused between 1/4" and 1/4 travel!

[MikeOH]

I find 1/4 travel to result in too high of an after start rpm.

1/4 travel for prime, but I back the throttle down before cranking to a position where I get around 1200 rpm after start.

Additionally, I find that varying the number of seconds I prime dependent on OAT to be important.  Sorry, but following the POH (open to full rich and then to return to idle cutoff) lacks that necessary detail.

[ArtVandelay]

Maybe that’s why 6 seconds or more works better for me, I just give it 1/4” and leave it, mixture rich, boost pump, then mixture lean. My POH omits the word “travel”, 1/4 travel would result in a start of 1500 RPMS I think, a bit much and probably harder on the engine than a 1000 RPMs start.

[Guest]

Throttle fully open, mixture full rich, fuel pump on until flow is indicated, close throttle then just bump off the stop, engage starter, enjoy noise.  200 HP Lycomings generally need less fuel priming than most others.

Never understood starting with mixture in ICO and pump left on as some PoH suggest.  No significant fuel will flow with mixture rich, fuel pump steals much needed power from the battery.

Clarence

[FloridaMan]

If you continue to have starting issues, get a slickstart. 

[eman1200]

Since I also fly a ‘75F I’ll chime in:

Throttle ‘cracked’ (sorry, I don’t measure whether it’s a 1/4” or what, but since I shut down at 1100rpm I basically just leave it there).
Mixture rich
Boost pump on for 5 or 6 seconds
Mixture ICO
Sit there for 5 seconds*
Crank that puppy

Since ‘sit there for 5 seconds’ isn’t in the PoH I clearly don’t know what I’m talking about. But it IS strange that she starts every time like that.

[Ragsf15e]

2 hours ago, FloridaMan said:

If you continue to have starting issues, get a slickstart. 

Or these days, get a Surefly - get rid of the SOS and the Slickstart.

It sounds like you can hot start it ok which is usually where new owners have lots of problems.  An io-360 is pretty easy to start cold (although “cold” means ~40f +, colder than that should be preheated).  Like almost foolproof.  

If the above techniques don’t work for you, there are a couple mechanical issues that can make it more difficult to start.

Failing SOS, failing left mag, fouled plugs are a few...

 

*The Lycoming guidance I’ve seen says preheat below 20f, but I generally use 40f.

[carusoam]

<20°F is where 100LL gets tougher to evaporate...

<40°F is where oil gets tougher to spread around...

SO... pick your pre-heat temp based on your needs.

If you have access to a pre-heater... use it.   

Below 20°F you may need a pre-heater...

Continental has an amazingly low recommendation for needing pre-heat...

Engine manufacturers don’t always have our wallets in mind...

Best regards,

-a-

[Casey020]

On 2/29/2020 at 7:48 PM, Htmlkid said:

I recently purchased a 1975 Mooney M20F and Im still struggling with cold starts. My current procedure is turn on master, turn on booster pump, throttle forward, mixture to full rich, pull back throttle to 1/4 and pull mixture all the way back, then if she starts mixture full forward. But she almost never starts the first time... so I randomly do the same thing again... Any thoughts on what is wrong? Warm starts are no issue.

Pump the throttle four or five times with boost pump on, then 1/4 inch to start, leave mixture in. Cold engines need lots of gas to start

[ArtVandelay]

Pump the throttle four or five times with boost pump on, then 1/4 inch to start, leave mixture in. Cold engines need lots of gas to start

And what does the pumping the throttle do for you?

[RobertGary1]

10 hours ago, Casey020 said:

Pump the throttle four or five times with boost pump on, then 1/4 inch to start, leave mixture in. Cold engines need lots of gas to start

Are you talking about carbureted or injected?

 

-Robert