Start Issue after Annual

[DrBill]

Before annual, my M20E started like all the articles indicated.  Push in till "running" let out and advance mixtuer.  After annual,  engine will not "run" until I stop pussing "IN".  Then the engine starts and runs right away.  I demonstrated this to the A&P today.  He is investigating.

Given that he had the left mag out for the "94 AD which was done but never logged, something changed.  Looking at the schematic, would these symptoms indicate that he swapped the 2 wires on the left mag ?

Once running, the mag checks are good and performance is right where it was.

Thanks

BILL

 

[orionflt]

Sounds like the spark advance is not working, the wire to the spark advance may not be terminated correctly. When your holding in, normal spark is disabled, so if it starts as soon as you release the the engine is startling on normal spark vs the advanced spark for easier starts. (Advanced spark fires sooner, and uses a coil to produce a better spark for starting)

Brian

[N601RX]

The shower of sparks is not working, or the left mag is completely dead.  The left mag has 2 sets of contacts in it, one for starting and one for running. The starting set is retarded to 0 deg while the running set is at 25deg.  Durring starting the right mag is grounded out.

 

Maxwell has a good article on his website that describes it.

[Hank]

Happened to me twice--once when the left mag's cranking capacitor went out, once when the capacitor in the Shower of Sparks went out. Neither is expensive nor difficult to replace.

 

The buzz shows that the SOS is vibrating, but it's not getting a spark.

[ELT]

Hi Bill,

I had the same problem after annual in April.  Mechanic talked to Don M., replaced ignition switch, SOS, P leads points in Left mag and then sent the 50 hour Left mag back for check. The engine shop found no problem with the mag but on general principles did replace the starting points again and OPENED THE POINTS MORE.  It started working.  I really think the problem was that the points needed to be opened more,  The ignition switch was worn and we burned up the SOS module trying to crank it.  Kevin, my mechanic and I were talking about this today.  Kevin did the right thing and ate many hours of labor and the parts.  I researched this probklem on the Mooney Tech site and others have resolved the problem without finding a "smoking gun".   I really think my problem was that the starting points in the left mage need to be opened more.  If you want to call me 919.819.3451.  We wasted 3 weeks trying to fix it.

Eddie

[DrBill]

My A&P likes Eddie's point gap idea and we will try it tomorrow or Thursday.  I'll keep everyone posted.

BILL

[N201MKTurbo]

This happened in my F once. The retard breaker wire inside the mag had rubbed against the inside of the mag and shorted to the case.

[Mooneymite]

Good general info here:

http://www.donmaxwell.com/publications/MAPA_TEXT/Shower%20of%20Sparks/Shower%20of%20Sparks.htm

Sounds like Don may address your issue:

Symptoms of a failing SOS system

1. Engine kicks back during starting

2. Hard starting

3. Engine starts when the key is released to the both.

......

[DrBill]

Thanks to all who replied.. Today my A&P and I inspected the left mag and found the retard points almost closed at max open position. They may have been completely closed. When set at the right gap (0.018 according to my mechanic) and re-installed and timed correctly, the problem is GONE.

Of course Don's document covers this but given that it started after my left mag was inspected, led me to believe the problem was with the mag.

Thanks to Eddit (ELT) who made himself available by phone for me and my A&P.

I'm now lookig forward to an event free trip to OSHKOSH on Sunday !

THANKS AGAIN EVERYONE !

BILL