skydvrboy

Engine starting problem

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I recently had a new starter installed on my M20F.  In doing so, it was found the at the ignition switch was arcing, so a new ignition switch kit was installed.  Since this work, I have had difficulty in starting the plane.  I go through my normal starting procedure (throttle 1/4", mix full rich, fuel pump on 3-5 seconds) and it just cranks away.  Almost without fail, no matter how long I crank, the moment I release the key the engine starts.  At first I thought this was just coincidence, but it has happened several times now.  Any ideas on what might be wrong?

I considered the mags, but they pass at run up.  I have not tried an in-flight mag check since this issue started.  I also haven't listened for the shower of sparks to see if that may be the problem.  I'll be taking it back to the mechanic on Saturday to check it out, but I thought it would be best to offer some clue as what may be going on here.

 

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Check the wiring to the SOS. Some ignition switches do not have the proper terminals for SOS activation. Disconnect the starter and listen for the SOS. When you let go of the key the engine fires off both mags bypassing the start circuit on the right? mag. 

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The switch shuts down right mag during start sequence so it will use the sos and left mag at 0 tdc timing.  The instant you let off the switch, the both mags comes on line normally... and in your case fires the engine.  

Something is wrong with your switch wiring or left mag/sos wiring. Likely the switch is grounding both mags in the start position instead of just the right or something similar. That would still support normal mag check. 

Im no a and p, but I learned this on MS like a week ago.

Edited by Ragsf15e
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ReCheck your wiring on the new switch, does your SOS box make noise when key is full right, look at SOS box and make sure the wires are connected.

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54 minutes ago, Shiny moose said:

ReCheck your wiring on the new switch, does your SOS box make noise when key is full right, look at SOS box and make sure the wires are connected.

Full right, but not yet pushed.,,

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Do yo hear the starter vibrator? If it starts when the key is released it’s my guess that the retard breaker is not firing.

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Check the switch for wiring and proper jumper that is in there...

There is a thread around here for the switch...

best regards,

-a-

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I don’t know if the shower of sparks is working or not. I didn’t specifically listen for it last time I started it. It’s pretty hard to hear even when I do.  My ignition was replaced at some point with one that starts when turned and doesn’t push in.

I’ll read the Don Maxwell publication and see if that answers some of my questions.

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7 hours ago, skydvrboy said:

I don’t know if the shower of sparks is working or not. I didn’t specifically listen for it last time I started it. It’s pretty hard to hear even when I do.  My ignition was replaced at some point with one that starts when turned and doesn’t push in.

I’ll read the Don Maxwell publication and see if that answers some of my questions.

Your ignition switch should have a two positions during start up. Turning to start engages the SOS starter vibrator, pushing engages the starter. Should be easy to hear.

Edited by Shadrach

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@Shadrach Yes, but mine was replaced with one that doesn’t push in.  When you turn it past “both” it engages both the stater and the SOS.

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For a cold start: I prime the engine, leave the fuel pump on, crack the throttle to around 1000-1220 RPM (an initial guess), and crank with the mixture closed. Once I start cranking, I slowly advance the mixture until the engine catches. This procedure is somewhat similar to the Maxwell flooded start. However, I leave the pump on for a cold start.

For a Hot Start: I use the Maxwell procedure and it hasn't failed me yet. Just a note... I don't perform a hot start with the fuel pump on.

Edited by David_H

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40 minutes ago, David_H said:

For a cold start: I prime the engine, leave the fuel pump on, crack the throttle to around 1000-1220 RPM (an initial guess), and crank with the mixture closed. Once I start cranking, I slowly advance the mixture until the engine catches. This procedure is somewhat similar to the Maxwell flooded start. However, I leave the pump on for a cold start.

For a Hot Start: I use the Maxwell procedure and it hasn't failed me yet. Just a note... I don't perform a hot start with the fuel pump on.

Oh boy, can o worms!

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59 minutes ago, David_H said:

For a cold start: I prime the engine, leave the fuel pump on, crack the throttle to around 1000-1220 RPM (an initial guess), and crank with the mixture closed. Once I start cranking, I slowly advance the mixture until the engine catches. This procedure is somewhat similar to the Maxwell flooded start. However, I leave the pump on for a cold start.

For a Hot Start: I use the Maxwell procedure and it hasn't failed me yet. Just a note... I don't perform a hot start with the fuel pump on.

Try this:

Cold

1" of throttle

Open mixture full

elect pump on for 6 aligators

mixture closed

Pump off

Crank.   open mixture when it pops.

 

Hot start

Shut off with mixture at 1100 Rpm

Don't touch anything.

Crank

advance mixture when it pops

 

Flooded

How do you know it is flooded?   When it dies when you advance mixture

Throttle full open

Mixture closed

Crank

When it pops do the two handed dance to pull throttle back and get mixture up.

 

For the OP your mechanic does not know what they are doing.  Wrong Switch or wrong wiring.

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Perhaps I should have included the following disclaimer:

The stated procedure works for me and might be worth trying, however there could be better ways. Try it at your own risk.

That said, I have not had issues starting the IO360. I could see how that could change if the engine starts misbehaving.

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I don’t understand why people are giving starting procedure advice to someone that is clearly having an ignition problem. Given that he’s been able to cold start his plane just fine up until the new ignition switch, what makes you guys think he now needs advice on cold start procedures? If you want to debate the myriad of ways to start an IO360, start a new thread.

Edited by Shadrach
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10 hours ago, skydvrboy said:

@Shadrach Yes, but mine was replaced with one that doesn’t push in.  When you turn it past “both” it engages both the stater and the SOS.

Why did you agree to that? The two position start switch gives you an easy verification that the vibrator is functioning. My armchair internet analysis is as follows.  Both mags are grounding in the start position (no spark @25°BTDC) and the left mag retard breaker (0°) is not producing spark. When you release the key, it ungrounds the mags and both mags fire at 25°BTDC causing  the engine start. Keep in mind that the retard breaker is powered by the SOS. Without SOS, you’ve no ignition event until the key is released. 

Continued operations under this scenariois is a recipe for engine kickback and a broken starter shear pin. I would urge you to cease all operations until your mechanic can verify ignition function. If you keep using it this way and take out your starter, your in a world of needless hurt.

Edited by Shadrach
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9 hours ago, skydvrboy said:

I don’t know if the shower of sparks is working or not. I didn’t specifically listen for it last time I started it. It’s pretty hard to hear even when I do.  My ignition was replaced at some point with one that starts when turned and doesn’t push in.

I’ll read the Don Maxwell publication and see if that answers some of my questions.

As others have stated. Ensure you have the correct switch installed, I believe 10-357210-1 is correct (please verify). Full right and you should clearly hear your SOS buzzing, also grounding both 20-25 BTDC points, while ungrounding your retard breaker 0 BTDC on the left mag. Pushing the key in will turn the starter, two separate functions, both needed. You clearly stated that starting issues started after a new switch was installed, start there! 

Edited by Shiny moose

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11 hours ago, skydvrboy said:

I don’t know if the shower of sparks is working or not. I didn’t specifically listen for it last time I started it. It’s pretty hard to hear even when I do.  My ignition was replaced at some point with one that starts when turned and doesn’t push in.

I’ll read the Don Maxwell publication and see if that answers some of my questions.

Make sure that you get/ got a TCM/Bendix magneto switch.  The ACS version doesn’t show an approval for Mooney.

Clarence

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4 hours ago, Shadrach said:

Why did you agree to that?

It was that way when I bought the plane, done by a previous owner.  Up until the starter was replaced, and the "guts" changed out on the ignition switch, I had no starting issues, hot or cold.  The ignition switch itself is the same and operates the same way, the mechanic repaired it with an overhaul kit.

I'll get it down to the mechanic tomorrow morning, on the same field so no need to start the plane.  After reading DMax's shower of sparks article referenced earlier, it seems it should be pretty easy to just disconnect the starter relay and verify if the shower of sparks is connected.  I'll reply with our findings when we have something definitive.

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32 minutes ago, skydvrboy said:

It was that way when I bought the plane, done by a previous owner.  Up until the starter was replaced, and the "guts" changed out on the ignition switch, I had no starting issues, hot or cold.  The ignition switch itself is the same and operates the same way, the mechanic repaired it with an overhaul kit.

I'll get it down to the mechanic tomorrow morning, on the same field so no need to start the plane.  After reading DMax's shower of sparks article referenced earlier, it seems it should be pretty easy to just disconnect the starter relay and verify if the shower of sparks is connected.  I'll reply with our findings when we have something definitive.

It’s conceivable that your previous ignition switch had a jumper in place to engage the SOS and starter at the same time. When the switch was “repaired”, it was returned to stock.  Would you mind posting the P/N of the switch kit? I’m just curious.  

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6 hours ago, Shadrach said:

Given that he’s been able to cold start his plane just fine up until the new ignition switch, what makes you guys think he now needs advice on cold start procedures? If you want to debate the myriad of ways to start an IO360, start a new thread.

After re-reading the first post, it does appear as though the switch may be the problem as many have said. -_-

The OP probably thought the same thing about being able to start his plane. Hopefully he's able to get it sorted out soon.

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49 minutes ago, Shadrach said:

It’s conceivable that your previous ignition switch had a jumper in place to engage the SOS and starter at the same time. When the switch was “repaired”, it was returned to stock.  Would you mind posting the P/N of the switch kit? I’m just curious.  

The way it was wired before engaged the SOS and the starter at the same time, I just don't know if it still does or not.  I'll see if I can find the P/N on the receipt, if not I'll get that from him tomorrow.  All I have right now is the receipt, as the repair has not yet been documented in the log book.  I'll get that done tomorrow as well.

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38 minutes ago, skydvrboy said:

The way it was wired before engaged the SOS and the starter at the same time, I just don't know if it still does or not.  I'll see if I can find the P/N on the receipt, if not I'll get that from him tomorrow.  All I have right now is the receipt, as the repair has not yet been documented in the log book.  I'll get that done tomorrow as well.

What you describe is not stock. I have never met an SOS system that didn’t have the six position switch. I look forward to finding out which switch was actually used.

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