e5cap

[e5bcap]

Hello all. first time on the site. I have a 1970 M20F that i have difficulty starting during hot weather and short stops.

[Ragsf15e]

5 hours ago, e5bcap said:

Hello all. first time on the site. I have a 1970 M20F that i have difficulty starting during hot weather and short stops.

Hot starts are a common issue.  Have you had the airplane long?  Has it been doing this consistently or has it gotten worse?

I recommend searching with Google, “Mooney Hot Start”.  You will find lots of threads on this.

personal technique for hot/warm/lukewarm starts... shut down with mixture cutoff and throttle set at 1,000 rpm.  When you go to start, don’t touch anything! Don’t prime it. Don’t use fuel pump.  Just Crank it.  When it fires, be ready to increase mixture to rich. 

Unless you have an ignition or fuel problem making this worse, it’s purely a technique issue and easy to learn to start reliably.

Edited May 4, 2019 by Ragsf15e

[Shiny moose]

14 hours ago, Ragsf15e said:

Hot starts are a common issue.  Have you had the airplane long?  Has it been doing this consistently or has it gotten worse?

I recommend searching with Google, “Mooney Hot Start”.  You will find lots of threads on this.

personal technique for hot/warm/lukewarm starts... shut down with mixture cutoff and throttle set at 1,000 rpm.  When you go to start, don’t touch anything! Don’t prime it. Don’t use fuel pump.  Just Crank it.  When it fires, be ready to increase mixture to rich. 

Unless you have an ignition or fuel problem making this worse, it’s purely a technique issue and easy to learn to start reliably.

+1 on this. The only question would be, when is it a hot start?  How long after shutdown do you consider this procedure?  At what time does it turn into a normal start. best thing for starting that I did on my F was to install a sky tec starter. 

[ArtVandelay]

+1 on this. The only question would be, when is it a hot start?  How long after shutdown do you consider this procedure?

It’s a hot start if engine temperature is +10° more than ambient temperature. When I start my engine after an oil change (2 hours later), I treat it as a hot start.
If you want more consistent starts, try firewalling the throttle and mixture for 10+ seconds, this dumps all the hot gases and fuel, so your fuel lines are empty. No vapor lock, the fuel lines get a fresh supply of cool fuel.
Readjust controls to normal hot start position.

It may take 10-15 blades, if you want to try for less, leave mixture at firewall, hit boost pump just long enough to see fuel pressure rise, then pull mixture and immediately start without delay (otherwise fuel in lines start to vaporize again). The risk with this technique is it’s easy to flood it if you’re slow to stop the pump.

If it’s a short stop and I still have fuel pressure in the green, I’ll skip the above because normal hot start technique works fine.



Tom

[e5bcap]

I have had the plane for 7 years and has always been an issue but has slowly gotten worse. I had the left mag, starting switch, and starting vibrator rebuilt in 2017 chasing another problem that turned out to be a short that was easy to see on the P wire at the left mag. checked the plug wiring found it OK. pulled the starting vibrator and found the contact points deeply pitted in one spot on lower point and a raised area on the upper point. cleaned them up and looking for a new set of contact points. Aircraft spruce is out of stock, in case anyone has a suggestion on where to get them.  Thanks for all the help and ideas. She starts better and I think I have to really work on my technique to prevent flooding the engine. I hate listening to that starter work so hard.

[Ragsf15e]

13 hours ago, Shiny moose said:

+1 on this. The only question would be, when is it a hot start?  How long after shutdown do you consider this procedure?  At what time does it turn into a normal start. best thing for starting that I did on my F was to install a sky tec starter. 

If you even consider the possibility of the engine being remotely warm, consider it a hot start.  If hot start technique doesn’t work, no harm done because no fuel was added.  Let your starter cool for a minute and then if you don’t think it’s hot, prime it as normal.

If you prime it on the first start, it’s very easy to flood it.  Still not a big deal if you know the technique for a flooded start, but you do need to decide to transition to that technique as it’s different.

Flooded start - Prime it 3-5” to make sure it’s flooded.  Full throttle, mixture cutoff.  Crank it.  Very Slowly pull back throttle till it starts.  Then throttle 1000, mixture rich.  It takes 4 hands.

So, if the engine may be warm, try hot start.  That works 99%.  If no, try normal start.  If no, flooded.  That works for me anyway.

Edited May 5, 2019 by Ragsf15e