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After having 7741M for 6 yrs now I thought I had a good handle on hot start, cold start or intermediate starts. She finally has shamed me at the pumps the other day and made me look like a first time owner. Flooded out after a few cranks. I had to make the walk of shame to the FBO after it would not start and let it rest for a while. Finally started after about 30 minutes.

Cranked up easy last week and taxied to the pumps. Went to start and no, no then flooded badly and finally caught after about 30 minutes break, Had to use the flood start technique. Coughed and spit, but did clear up.

Went out the next day for afternoon flight and no go. Crank, Crank, Flood.. went home had dinner and came back about an hour later after dinner and leaving a battery charge on it. Yes. it pulled the year old battery down slightly. I tried several times with no luck and one more time just as I was ready to throw in the towel it gave me a tease and huffed and puffed and then failed. One more flooded try and it finally started using flood technique.

Each time after it did finally start the Mag Check and the drops were spot on with no abnormal deviation. The engine ran perfectly during taxi and flight. 

Got up the third day for out of the town trip and no dice at all. Flood within the first few minutes of cranks and no indication of fire.

Same today after a full battery charge. Now getting nothing, not even comes close to catching, just cranks.

Started with the logical stuff after talking with my MX.  New plugs, still no dice. He suspects the Mag just from phone diagnostics. Only thing that throws me is the few times it did catch after the flooded. Now it gives me nothing, but floods right after the few failed cranks..and by flooded I mean dripping. So yes very flooded.

Logs show Mag was overhauled in 2010 about 400 hrs ago.

Any thoughts? Mag? We are getting fuel obviously, new plugs. 73 M20E.

I know we have a search feature and I have spent some time poking around, but sometimes it's easier to ask. If a mag, go OH or new? Right now it's dead in the hanger. My mechanic will be checking it tomorrow, just tossing this out there to see what the Mooney experts think.

Thanks in advance,

-Tom

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I had a similar problem with an IO-360A3B6 with two new Slick mags (left impulse coupling).  Lycoming remanufactured at 200 hours.  Would tease me with occasional puffs with normal technique, but I could eventually get it to fire with a flooded-type cold start.  Problem was getting worse over time.  Switching to fine-wire plugs helped initially, but kept getting worse.  Once running, no problem.  Mag checks at idle and on runup were ok, so I kept thinking it was bad technique.

I had my A&P bench test the left mag, and he confirmed weak spark.  He IRAN'd the mag, and reset the e-gap.  Afterwards, starts are back to 2-3 blades before catching.  I plan to have the right mag IRAN'd next year or if it fails a runup mag check.

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Thanks guys..I embarrassed to say I'm not sure if it has a SOS or Impulse Coupler. I know just enough to be dangerous, but read all about the differences last night before posting this to the forum, so now I know what to look for (or listen for). Even read the Don Maxell article that was posted online a while back.

I'm going to the hanger (as well as my MX) to check this morning. I'm thinking it's ICoupler. The cowl is off and I plane to stop by on my way to work. This kind of stuff drives me nuts, I'm a OCD thinker guy and unfortunately let stuff like this bother me until I figure what the problem is.

My explanation of events was kind of confusing. I typically use our standard regular start procedure that most of us post and have never had an issue over the last 6 yrs with an occasional hot start flood, but usually can clear it right away, but something is different now.

Now when it does not catch and keeps swinging it eventually floods out, then I go full firewall with throttle and slowly move the mixture up hoping to find the sweet spot for them to catch, first few times over the last few weeks it would catch after longer than usual swings or more repeated tries, now I'm finally to the point after repeated tries of any different technique it just cranks showing no life, not even a  tease of spit or puff of life and floods to a puddle.

-Tom 

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If you are doing a normal start (mixture at cutoff until it catches) there is no way it should EVER flood.  Either your technique is not what most of us do or there is something wrong with your fuel system.

Please describe your start technique in excruciating detail.  If you are in fact using mixture at cutoff until it catches, have your mechanic check your servo and mixture control.

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Thanks all. We've looked at it. Everything from ignition to vibrator etc appears working correctly. Final diagnosis appears to be Slick Mag 4347. Took a page from D Maxwell's book on the trouble shooting tips. Great info. Going with new and core exchange. Overhauled were back ordered and I feel more confident with the new vs. overhauled. Will post update after the install on Friday. Thanks for all the input. As always, appreciate MS.

-Tom

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3 hours ago, Yetti said:

Flooded procedure is:   wide open throttle.  And no mixture until AFTER it starts.  Then do the two handed dance.

How do you know it is flooded?

When it pops and you add mixture and it dies.

Fuel dripping steady from the lower cowl immediately after failed start.

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3 hours ago, Bob - S50 said:

If you are doing a normal start (mixture at cutoff until it catches) there is no way it should EVER flood.  Either your technique is not what most of us do or there is something wrong with your fuel system.

Please describe your start technique in excruciating detail.  If you are in fact using mixture at cutoff until it catches, have your mechanic check your servo and mixture control.

Technique for years..or what works for me since we all have a little variation. Cold start: Everything forward, BP on for 3-5 sec then off, throttle back to about 1/4" +/-, Mixture full aft, crank and slowly move mixture forward after it catches. Six years and counting, so far, so good.

Flooded..Throttle full forward, no BP, Mixture full aft, slowly work mixture forward until fires. Usually catches about an inch to inch half forward, as mixture clears pull throttle back from full forward. Again, that's what works for me.

Hot start.. Do not touch throttle since after shutdown, usually leaving at 1200 RPM or so, and slowly advance mixture. No BP.

 

-Tom

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6 minutes ago, Yetti said:

so why would you add fuel to a flooded engine?

Adding mixture after it catches and starts to clear, I guess I wasn't clear :)  Sometimes I have to hold my head just right, raise my lip and curl my toes..Just do whatever it takes, instinct kind of takes over as it gets close and fires. We all know the feeling.

 

-Tom

 

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I was going to add that if you call Lycoming tech support they will give you an air gap value across which your mag lead (set to fire #1) will jump an air gap to start the engine. I recall for the IO-360 it works out to be like 3/8” or thereabouts.  It’s a great tool for ignition troubleshooting because it tests your impulse, mag and harness in situ and together.   

Who works on your mags matters.... don’t send to jelly Kelly by reputation alone, and there are a few trusted names around the country. 

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11 minutes ago, TWinter said:

Technique for years..or what works for me since we all have a little variation. Cold start: Everything forward, BP on for 3-5 sec then off, throttle back to about 1/4" +/-, Mixture full aft, crank and slowly move mixture forward after it catches. Six years and counting, so far, so good.

Flooded..Throttle full forward, no BP, Mixture full aft, slowly work mixture forward until fires. Usually catches about an inch to inch half forward, as mixture clears pull throttle back from full forward. Again, that's what works for me.

Hot start.. Do not touch throttle since after shutdown, usually leaving at 1200 RPM or so, and slowly advance mixture. No BP.

 

-Tom

Hmm, check your POH?  Your cold start technique sounds a little aggressive.  Most cold starts I've seen call for priming by

  • Throttle 1/4"
  • Mixture full forward
  • Boost pump 3-5 sec
  • Mixture full aft

If you turn on the boost pump with full throttle and mixture full rich, you are pretty much pumping fuel at 17 gph into the intake manifold.  That's half a cup of fuel in about 5 seconds, more than enough to flood the engine and pour out the bottom.  It may be less fuel since the first 2-3 seconds the fuel is simply filling the empty fuel lines, but it only takes a second of flow at that level to flood the engine.  That being said, a very rich mixture on starting can partly make up for a weak spark, which may have hidden the problem for a while.

For flooded start, you should pull back throttle first before messing with mixture.  If you truly flooded it, you should have plenty of time to pull back the throttle to keep it under 1200 rpm.  You don't need to be careful with the mixture, just push it in a couple inches.  If you lean to the point of roughness during idle and taxi, you should know how little mixture you need.  All you need is a little more than that to keep the engine running.

I don't know if it's too late, but ask if there is anyone at your local airport who can bench test and IRAN the mag.  If it's just the e-gap setting, which it sounds like, it could be as little as $250 to repair.

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3 hours ago, TWinter said:

Technique for years..or what works for me since we all have a little variation. Cold start: Everything forward, BP on for 3-5 sec then off, throttle back to about 1/4" +/-, Mixture full aft, crank and slowly move mixture forward after it catches. Six years and counting, so far, so good.

Flooded..Throttle full forward, no BP, Mixture full aft, slowly work mixture forward until fires. Usually catches about an inch to inch half forward, as mixture clears pull throttle back from full forward. Again, that's what works for me.

Hot start.. Do not touch throttle since after shutdown, usually leaving at 1200 RPM or so, and slowly advance mixture. No BP.

 

-Tom

If you truly are not moving the mixture forward until after it catches, I don't understand where the fuel is coming from that you see dripping from the cowl.  That's why I'd look at the fuel system rather than the magneto.

Unless, of course, the full throttle while priming allows all that fuel into intake system.  I personally prime with the throttle in the starting position of about 1/4" forward.

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8 minutes ago, Bob - S50 said:

If you truly are not moving the mixture forward until after it catches, I don't understand where the fuel is coming from that you see dripping from the cowl.  That's why I'd look at the fuel system rather than the magneto.

Unless, of course, the full throttle while priming allows all that fuel into intake system.  I personally prime with the throttle in the starting position of about 1/4" forward.

When I have intentionally flooded the engine on hot starts, 3 seconds boost pump of full throttle/full rich is plenty to start fuel dripping on the floor.  The amount is rather frightening, I might add :o

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Update:

Mechanic installed the new left mag today. We had also replaced the plugs prior. SOS and all seem to test correct. Here is where we are now.

Got everything buttoned up for start up. Crank, crank still no turnover. Then he decides to check key ignition positions on the mags and if they were getting proper current. Turns out that when we get to the start position and I press the key in I'm getting ground at the left mag.

He took the P-Lead off the left mag (sp?..I not a mechanic, but learning a lot watching them trouble-shoot) tried again and the engine fired right up in a few swings. Shut down and did additional tries with P-lead back on the left mag. Again and no start. P-lead off the left again and it started right up again.

Disconnected the starter hot to just test the left mag. Everytime I pushed the key in for ignition  left mag shows grounding. Testing of the switch in / off/ rght/left mag showed ground at correct times, but the left is showing ground at start with ignition pushed in preventing start.  He's researching, but now we are to possible ignition switch defective. Anybody have thoughts about this or agree or disagree? if so what is the best (quickest source) for new ignition switch. Part # if anybody knows where and who to find one.  I'm starting to have withdrawals.

-Tom

  

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Sounds like the ignition switch has suddenly stopped operating properly... or it got re-wired along the way?

That may require studying how the switch actually works.  What makes it ground, and when.... could be how the new left mag is or isn’t wired properly?

@M20Doc may have these kind of answers....

Best regards,

-a-

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11 minutes ago, carusoam said:

Sounds like the ignition switch has suddenly stopped operating properly... or it got re-wired along the way?

That may require studying how the switch actually works.  What makes it ground, and when.... could be how the new left mag is or isn’t wired properly?

@M20Doc may have these kind of answers....

Best regards,

-a-

Still researching..The switch has not been touched (wiring) since I've owned it (6 yr). The mag is brand new from Spruce and part #s are correct. Really think 40 yrs of switch off/on may have reached it's last swing of the blade. I must say it did feel good hearing the girl fire up after taking the P-Lead off. Still trying to find a source for replacement. of switch.

Thanks

-Tom

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I’m wondering if there are two ways a mag can come wired...

Meaning, it may be possible that the new mag might be wired 180° out of sync with what you need...

I was reading about the istart system in the other thread... there is so much complexity in the starting, and timing and grounding of the left mag...

hope you find your issue soon.

Best regards,

-a-

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Try AS for rebuild kits for the start switch...

http://www.aircraftspruce.com/catalog/elpages/ignitionswitchkit.php?gclid=Cj0KCQiAwp_UBRD7ARIsAMie3Xbng0jSrc0QqlJjo5uWdbSXNqRA7SnHnaVFYH2gzC7pYoUSLbPuCn0aArpGEALw_wcB

notice the note on the jumper on position #1? Do you have one there, does it belong there?

Did you receive the correct mag?  (Ordered the correct one, but got something different?)

PP thoughts only. I didn’t do the needed research...

Best regards,

-a-

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