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Engine starting problem


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Here’s a Follow up on my switch installation after cleaning and lubrication-

the push to start function is apparently not very happy having dielectric grease on the contacts...all the other switch functions worked fine, but the push to start was intermittent until ( I assume) the grease got pushed out of the way...( it was only a very thin coating that I applied). Even after that, starter engagement required considerable force to make a positive connection, until I removed the Luberex grease. All is well now.

Perhaps this is why Bendix didn’t lubricate these switches from the factory?? 

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  • 8 months later...
On 3/14/2019 at 2:50 PM, skydvrboy said:

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.

 

Your ignition switch is shorting out when you turn it all the way to the right and push in the switch to start it.  When you release the switch slightly to the left the short is closed and it starts.  The problem is in your switch.  I have seen that issue before.

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This is a problem dear to my heart. I struggled with this for two years. Here is what I did to finally solve the problem; 1. get rid of the S.O.S. and get the mag booster system. 2. don't follow the recommended procedure. I put boost pump on and leave it on until you have started. Set your throttle, go full rich two pumps, then from lean start crank and enrich until she starts. Not complex. 

The point is quite simple. The right spark and air/fuel ratio and its going to start. The mag booster give a really high voltage spark. The two pumps prime and advancing the mixture mean you will hit the right ratio. Leaving the boost on just makes sure you have fuel pressure. 

This is what works for me. Doing this completely changed my experience with my Mooney. Starts every time. 

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  • 2 weeks later...

Ignition problem solved!  The IO-360 A1A came with a shower of sparks system that works with your ignition key.  (A bad ignition switch is possible but not the most likely culprit.  Testing the switch is a pain in the butt because you have to take it out of the dash and check the outputs of the various connectors as depicted in the maintenance manual.  Mine checked fine.)  The mags are set to 25 degrees BTDC.  So that you don't get kickback during the start the ignition switch shorts out the right mag and the part of the left mag that fires at 25 degrees BTDC and energizes a separate set of points in the left mag that works with the shower of sparks box and fires at TDC for easy starting.  Once the ignition switch is released from the far right spring resisted position it goes back to both and both mags come to life. (That is why many people can get their Mooney to start when they release the switch.) 

The shower of sparks box is mounted on the copilot side on the firewall as far up as you can get.  If you have the old style windshield with the access panels in front of the windshield count yourself lucky.  I have a 201 windscreen which makes retrieval more suited to a contortionist.  (Note: Even if you hear the shower of sparks box buzzing it can still be inoperative.)  The shower of sparks box has a coil and condenser in it with a set of points.  The distance from the points to the coil which actuates the points is supposed to be gapped at .025 in.  You do not gap the points but the distance between the coil and points.  Mine was gapped too wide and would not actuate the points as it should have.  After dressing the points and setting the gap between the coil and point set the box came to life and pushed the sparks as it should have.  I suggest checking the spark at the P lead going into the left mag next to make sure you are getting spark there.  Use a multimeter with a beep function so you can wiggle the P lead if you don't get spark.  Many times from being flexed many times over the years there may be a short at the end of the P lead where it goes into the mag.  I ended up trimming off 3 inches of the end of the lead and re soldering the tip of the lead to get rid of an intermittent short.   The final check for the SOS system is to set number one cylinder at TDC on the compression stroke and check that the spark plug fires when you turn the key to the right. (Remove the spark plug and be sure the spark plug side is grounded to the engine and the tip is close to the case so the spark can jump.) You may have to move your prop slightly back and forth to catch the ignition exactly at TDC to get a proper test.  Note: Do not stand in the prop arc or grab the prop in a way where you would get hurt if your help accidentally bumped the starter. (Disconnecting the solenoid to starter lead is not a bad idea) Also note that the SOS box packs a punch. Be careful what you touch when power is on it. 

I hope this helps.  It was a frustrating process of problem solving but finally got to the bottom of it.  I am sure that people with a shower of spark ignition system who encounter similar symptoms have some variation of the component problems checked or fixed above. 

Possible problems: Ignition switch, shower of sparks box, lead as it passes through the firewall (check not grounding at grommet), tip of P lead and left mag retard assembly.

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9 hours ago, Louis said:

Ignition problem solved!  The IO-360 A1A came with a shower of sparks system that works with your ignition key.  (A bad ignition switch is possible but not the most likely culprit.  Testing the switch is a pain in the butt because you have to take it out of the dash and check the outputs of the various connectors as depicted in the maintenance manual.  Mine checked fine.)  The mags are set to 25 degrees BTDC.  So that you don't get kickback during the start the ignition switch shorts out the right mag and the part of the left mag that fires at 25 degrees BTDC and energizes a separate set of points in the left mag that works with the shower of sparks box and fires at TDC for easy starting.  Once the ignition switch is released from the far right spring resisted position it goes back to both and both mags come to life. (That is why many people can get their Mooney to start when they release the switch.) 

The shower of sparks box is mounted on the copilot side on the firewall as far up as you can get.  If you have the old style windshield with the access panels in front of the windshield count yourself lucky.  I have a 201 windscreen which makes retrieval more suited to a contortionist.  (Note: Even if you hear the shower of sparks box buzzing it can still be inoperative.)  The shower of sparks box has a coil and condenser in it with a set of points.  The distance from the points to the coil which actuates the points is supposed to be gapped at .025 in.  You do not gap the points but the distance between the coil and points.  Mine was gapped too wide and would not actuate the points as it should have.  After dressing the points and setting the gap between the coil and point set the box came to life and pushed the sparks as it should have.  I suggest checking the spark at the P lead going into the left mag next to make sure you are getting spark there.  Use a multimeter with a beep function so you can wiggle the P lead if you don't get spark.  Many times from being flexed many times over the years there may be a short at the end of the P lead where it goes into the mag.  I ended up trimming off 3 inches of the end of the lead and re soldering the tip of the lead to get rid of an intermittent short.   The final check for the SOS system is to set number one cylinder at TDC on the compression stroke and check that the spark plug fires when you turn the key to the right. (Remove the spark plug and be sure the spark plug side is grounded to the engine and the tip is close to the case so the spark can jump.) You may have to move your prop slightly back and forth to catch the ignition exactly at TDC to get a proper test.  Note: Do not stand in the prop arc or grab the prop in a way where you would get hurt if your help accidentally bumped the starter. (Disconnecting the solenoid to starter lead is not a bad idea) Also note that the SOS box packs a punch. Be careful what you touch when power is on it. 

I hope this helps.  It was a frustrating process of problem solving but finally got to the bottom of it.  I am sure that people with a shower of spark ignition system who encounter similar symptoms have some variation of the component problems checked or fixed above. 

Possible problems: Ignition switch, shower of sparks box, lead as it passes through the firewall (check not grounding at grommet), tip of P lead and left mag retard assembly.

On the newer Fs shorting at the firewall pass through is not going to happen.    It is a big cannon plug with all the leads soldered into the plug at both ends.

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