M20C not starting

[M20 Ogler]

I have Shower of sparks ignition. I can hear the vibrator buzzing when the ignition key is turned to “start”. Then I press the key in to engage the starter. But the engine won’t fire. Sometimes it gets started after I release the key. 
 

My battery drains after two or three attempts at cranking for 10 to 15 seconds so then I have to put back on the charger for a few hours. Maybe my battery is toast? 
 

Any quick and easy things I can check before I call the shop? Wires that may be loose or maybe I can spray electrical contact cleaner in the vibrator box? 
 

Thx 

[Hank]

The engine starting when you release the key is a signal of a failing left magneto. During engine start, the right mag is grounded, as only the left mag has a set of retarded points used at startup; letting go of the key activates the right magneto and the engine may start then.

My left mag died in the air, and after landing neither love nor money would make it start again; not even my enhanced vocabulary made it run.

[MooneyMitch]

In addition to Hank’s information, a faulty ignition switch could be applying a ground on the left magneto P lead wire during the starting phase.  Or possibly a bare wire point along the left magneto P lead wire path from the ignition switch to the left magneto could be picking up a ground too.   
 

[47U]

‘Oh Lord, stuck in Lodi again…’

When the engine starts after releasing the key (and the right mag fires, as Hank describes), have you done a mag check?  Does the left mag make spark then?  I’m guessing hearing the shower of sparks buzzing means that box is probably working, but an inspection of the wiring between the shower of sparks and the left mag (as MooneyMitch suggests) might reveal an issue.

Which side of the firewall is your shower of sparks.  Do you have a 201 windscreen?  

 

[M20 Ogler]

Yes I do a mag check before takeoff and they both work or else I would not fly. I have the original windscreen. 

[47U]

3 minutes ago, M20 Ogler said:

I have the original windscreen.

I’m guessing the SoS box is on the cockpit side of the firewall.  Pull the top cowl and inspect the wiring from the left mag back to the firewall.  If there’s a bad wire, it’s probably on the engine side.  The P-lead wire is probably shielded (unless it’s been replaced with shielded wire under the insulation).  If that looks ok, then pull the avionics access and inspect that wiring from the SoS box to the firewall.  If still no smoking gun, depending on your level of mx ability, remove a plug lead from a plug on the left mag and install a plug in it.  Ground the plug to the engine and have someone energize the SoS.  DON’T ENGAGE THE STARTER!  And, don’t get shocked.  

I removed my SoS years ago, and never had to troubleshoot it, so I don’t remember if it buzzes that means for certain it’s making spark.  There’s an SoS troubleshooting guide, probably in the downloads section.  I still have my SoS box, in case you need one.

[Fritz1]

check as stated by 47U, if SOS dead think about a slick start booster, 3-4 times the bang of SOS, I had a dead SOS on my G-model once upon a time, replaced slick start, fired within one blade cold or hot

[Jim Peace]

curious when the mag inspection was done last?  

[M20 Ogler]

9 minutes ago, Jim Peace said:

curious when the mag inspection was done last?  

I think they where replaced around 250 hours ago 

Edited November 29 by M20 Ogler

[MooneyMitch]

We are all really trying to get you started.......

With my thoughts on grounded P lead during starting...................

1. render your engine from being able to start [disconnect battery lead at starter is one way].

2.  disconnect P lead from left mag.

3. with volt meter, set meter to DC voltage.

4.  attach black meter lead to disconnected P lead.

5.  attach red meter wire to 12V DC .

6.  turn on Master switch and verify meter registers 12V [this means your P lead is correctly grounded as it should be in this configuration]

7.  activate starter switch to START and voltage should disappear. [P lead should no longer show as grounded]

8.  this method will verify that your P lead wire/starter switch grounding feature is correct. [no foreign grounding from switch or frayed wire]

 

[N201MKTurbo]

Pull the point cover off the retard mag, check the wires for chafing and make sure the points are opening. You can do all this without removing the mags. 
 

I had this happen once, the wire to the retard breaker was touching the inside surface of the point cover and had warn through the insulation and the wire was shorted to the cover.

[MooneyMitch]

29 minutes ago, Fritz1 said:

check as stated by 47U, if SOS dead think about a slick start booster, 3-4 times the bang of SOS, I had a dead SOS on my G-model once upon a time, replaced slick start, fired within one blade cold or hot

Drifting away from trying to help this gentleman get his C started, here's an interesting story regarding the Slick Start Booster on my Mooney [previously installed by others].

I installed mags on my D/C model after 500 hour inspection.  Engine would not start until I'd release the START motion [limped into starting]  Checked and re-checked all installation over and over and over, thinking I'd done something incorrectly........ wiring, timing, etc.  All appeared correct........hmmm!

I discovered in start position, there remained a left mag P lead grounding with the P lead disconnected from the mag...............WHAT??

Eventually, hours later, I discovered that during the Slick unit installation/modification, certain wires are to be removed from the ignition switch.  One wire had not been removed from the switch during the modification.  That wire had been left in the aircraft wiring bundle and coincidentally began picking up a ground which was grounding the left mag P lead during the start procedure !  I disconnected the wire from the switch, taped it up and all was well again. 

 

[M20 Ogler]

Went to trouble shoot today and the plane started up and shut down multiple times no problem. Like it just rolled out the factory yesterday.
 

Can’t find any obvious shorts or open circuit. The wires and harnesses all look nearly new. Idk how to troubleshoot an intermittent problem. 

[Ragsf15e]

5 minutes ago, M20 Ogler said:

Went to trouble shoot today and the plane started up and shut down multiple times no problem. Like it just rolled out the factory yesterday.
 

Can’t find any obvious shorts or open circuit. The wires and harnesses all look nearly new. Idk how to troubleshoot an intermittent problem. 

Those are the worst!

[MikeOH]

2 hours ago, M20 Ogler said:

Idk how to troubleshoot an intermittent problem. 

Don't feel bad...I'm a career EE and I don't know how to troubleshoot an intermittent problem, either!

[takair]

On 11/29/2024 at 10:42 AM, M20 Ogler said:

I have Shower of sparks ignition. I can hear the vibrator buzzing when the ignition key is turned to “start”. Then I press the key in to engage the starter. But the engine won’t fire. Sometimes it gets started after I release the key. 
 

My battery drains after two or three attempts at cranking for 10 to 15 seconds so then I have to put back on the charger for a few hours. Maybe my battery is toast? 
 

Any quick and easy things I can check before I call the shop? Wires that may be loose or maybe I can spray electrical contact cleaner in the vibrator box? 
 

Thx 

I had this issue a few years ago.  As I recall, I just needed to clean/sand/file the contacts in the shower of sparks.  Ideally you replace them, but think they were not available.  You will probably find them pitted from arcing. 

[Pinecone]

17 hours ago, MikeOH said:

Don't feel bad...I'm a career EE and I don't know how to troubleshoot an intermittent problem, either!

It's easy.  It just requires more time than you have.  And increase in your vocabulary of swear words.  Some skin off of various parts of your body.  And, if you have hair, ripping some out.

And that might not even be enough.

 

[MooneyMitch]

Yep, intermittent is the worst for sure.  Spent many years at our west coast missile launch facility and running across an intermittent was frustrating.........until it raised its head and you could finally cut it off!!!   Patience and persistence..............it will reappear.  Something is grounding that left mag..............

[47U]

7 hours ago, MooneyMitch said:

Yep, intermittent is the worst for sure.  Spent many years at our west coast missile launch facility and running across an intermittent was frustrating...

We had a sensor with an intermittent issue.  Ring’d perfectly on the ground.  Finally, found a cannon plug (100+ pins) on a pressure bulkhead with one pin that was reversed, the crimp end was on the female side and the female end was crimped.  Pressurizing the bulkhead in flight created enough flex that the connection was intermittent.  A Lockmart tech rep found it.  Those guys were mostly ancient (compared to the blue suiters) but they knew their shit.    

[cliffy]

Age and treachery beat youth and looks any day of the week!  :-)

[Fly Boomer]

2 minutes ago, cliffy said:

Age and treachery beat youth and looks any day of the week!  :-)

I always warn the frisky youngsters that I cheat at every opportunity.

[Pinecone]

Old fighter pilot saying:

If you ain't cheatin', you ain't tryin'.

[phxcobraz]

I had almost the exact same issue earlier this year(see thread I posted). I was having intermittent trouble starting until one day it wouldn’t start at all. Checked continuity to all wiring to/from the ignition, shower of sparks, and the left mag. All checked out great, however my left mag was approaching overhaul/IRAN 500hr and in checking it we found the retard breaker not working. I figured the $500+ for the mag service was better put toward a new mag so I put on a Surefly electronic mag and it starts fantastic and so easy now. 

[MooneyMitch]

59 minutes ago, phxcobraz said:

I had almost the exact same issue earlier this year(see thread I posted). I was having intermittent trouble starting until one day it wouldn’t start at all. Checked continuity to all wiring to/from the ignition, shower of sparks, and the left mag. All checked out great, however my left mag was approaching overhaul/IRAN 500hr and in checking it we found the retard breaker not working. I figured the $500+ for the mag service was better put toward a new mag so I put on a Surefly electronic mag and it starts fantastic and so easy now. 

I like that issue explanation.