When I first got the plane last year I even had trouble with cold-starts....I eventually found that the POH recommendation of 3-5 seconds of boost pump was not enough....I now use around 7-8 seconds and have a 100% success now.....

It seems to me that if a hot start requires no boost, and a cold start requires 7-8 seconds, there must be some interim state that requires something between 0 and 7-8 seconds depending on how much the engine has cooled down... But how much boost and what corresponding CHT or shut-down time? Or maybe my theory is just plain wrong!

It seems as if my M20F engine behaves slightly differently than your M20J engine... - with these summer temperatures in Europe sometimes 3 seconds of boost pump are already too much and result in a flooded engine.
In winter I do need 3-4 secs but in summer 1-2 seconds of boost pump are enough to start my engine...
The hot start problems are due to the tiny fuel lines above the hot engine and the tight cowling space in the Mooney. I am 95% successful with my hot start technique anywhere between 15 minutes and 2 hours after shut down. After 2 hours the cold start procedure usually works as long as the outside air temperature is below 30°C and if nothing else works I run the flooded engine procedure.

Hi fellow members,

I am new EMPOA member that only signed up on Forum yeasterday, and this topic catched my attention..

We own a M20J Allegro with an IO 360 engine.
We suffered from the same problema on hot starts, that some times (in the beginnig) conducted to flodded starts). Finally we developed a procedure much like the ones you stated above and that are on the POH. We always do like this:

COLD START:
THROTLE- Full Forward
MIXTURE- Full Rich
BOOST PUMP- On for 3 secs (above 20/25ºC), or 5 secs (under 20/25ºC), and then Off.
THROTLE- 1 Inch
MIXTURE- Off
MAGNETO- Start and enrich Mixture slowly

WARM START (untill 2 Hours of shut down):
MIXTURE- Full Rich
THROTLE- Full Forward and then Idle (repeat twice)
MIXTURE- Off
MAGNETO- Start and enrich Mixture slowly
( Never in Warm Starts switch On the Boost Pump. Never!!)

FLOODED START:
THROTLE- Full Forward
MIXTURE- Idle
MAGNETO- Start, and expect to wait until 10-15 secs to the engine start to come alive)
MIXTURE- Enrich
If engine does not star after one attempt, wait 2 minutes before next attempt. This will save the life of your starter. If engine does not start after 4 attempts, wait 30 minutes to repeat the next 4 attemps. This will let yor starter to cool correctly.
If you suspect that the engine is very flooded (by wrongly use of Boost Pump on warm starts) or you feel strong smell of gas, you should wait for engine to leak the excess of fuel by it self (maybe 1 - 1,5 hour), or you can try to conter-rotate Propeller Blades, which will drain the excess of fuel in the engine by exploiting it by the drain pipe (you can check it visually). With this procedure, you will ear a strange noise from the propeller (it's normal) but you will save a lot of time waiting for the engine to drain the excesso fuel by it self.

After several years of unconfortable Hot and Flood Starts, when I didn't know what to do, I finally developed these procedures that never more let me down.

Hope these tips can be usefull to you
Cheers,
Frederico

Thanks Frederico, I too now have it all figured out for my J.....it seems we all have to use trial and error and come up with our own individual methods!

Cheers
Anthony

I use a method, what I found some years ago on Mooneyspace:
Before shutting down the engine, I increase speed to 1.200 rpm.
Start the hot engine as usual without using the boost pump. (Throttle 1/2", Mixture cut off, after engine fires, increase mixture to full rich) Never had an issue with hot engine anymore.