Starting Issues

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tafisama
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Re: Starting Issues

Post by tafisama »

My Flying club has a Jabiru J230 six cylinder which would start whenever it felt it wanted to especially when it was cold.Very inconveniencing it was.You would never tell if you were going to fly.After sometime they decided to just change all 12 spark plugs and boom she fires when you want it to.Spark plug resistance is the main factor and if you take into account the age of our aircraft,we should just change all plugs regardless of whether resistance is still within limits.

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XL2driver
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Re: Starting Issues

Post by XL2driver »

@paulmilo -
To answer your two questions -
Correct - I certainly did not make that recommendation, and correct, I don't recommend it be done.
Sorry no time to detail why though, but in short it was never an accepted procedure from the "factory operations" point of view, nor was it ever necessary. The likely cause of the problem is something else, as per the example of what tafisama explained above.
Hope that helps.
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paulmilo
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Re: Starting Issues

Post by paulmilo »

New plugs this annual then :-)
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Milo VH-KXY
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paulmilo
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Re: Starting Issues

Post by paulmilo »

Tried pulling the power back to idle when it stumbles. It ran for a bit longer, but still dies.

Next will be the top 4 plugs and then at the annual, the bottom 4
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XL2driver
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Re: Starting Issues

Post by XL2driver »

"pulling the power back to idle when it stumbles" - may I ask when you are doing this? Is this during the warm-up phase? Taxing after warmup? Or when?
Tks
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paulmilo
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Re: Starting Issues

Post by paulmilo »

See the thread above Paul, was suggested as one thing to try. It was upon startup, only if it stumbles, and only long enough to stabilise.

I went back to not double priming, and normal throttle setting. It starts ok, runs normal for 5+ seconds and then stumbles like fuel starvation.

Sometimes, without double priming, it is hard to start and then does the same. Double Prime pretty much starts every time making me suspect fuel.

If you add more power on start up (12-1300rpm) it will start and continue running. Then I reduce power to ~1000 5-10sec after starting. Not ideal but at least it’s warm here atm (20C).

It does this regardless of pump on or on auto. Has done this for at least 6 mths now. I was going to look at changing plugs in Aug for the annual anyway, but I’ll do 4 top plugs now and see if anything changes. All plugs passed muster last annual.

Cheers
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paulmilo
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Re: Starting Issues

Post by paulmilo »

I think comments re plugs may be correct as the last time I had starting issues (last year), I changed the aux battery just prior to the annual and starting improved immediately.

I’m flying less now (~2 weekly) with no power at the hanger to charge, and starting has been getting progressively worse again. Low aux power with suspect plugs perhaps?
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tafisama
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Re: Starting Issues

Post by tafisama »

Try checking the history after flight on the VM 1000 or during flight to identify a cylinder running cold.On start up keep your eyes on the fuel pressure to see if it`s dropping when it dies.

tafisama
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Re: Starting Issues

Post by tafisama »

paulmilo wrote:
Fri Apr 24, 2020 1:43 pm
Tried pulling the power back to idle when it stumbles. It ran for a bit longer, but still dies.

Next will be the top 4 plugs and then at the annual, the bottom 4
Hie Paul,how have you gone with your issue of engine cutting out.Mine is now sorted after putting new 4 top spark plugs.I had an interesting find this morning after removing the top spark plugs.The center electrode had elongated instead of it being circular.Three had resistance out at 6kohm.One was firing on one electrode.After replacing them,it started and ran at 1000rpm without stalling but I left the pump on.The acceleration during TO was pleasing and with 10degrees flap,she climbed well.One cylinder is running cold at around 260 degrees when others are around 298.Will do the bottom plugs next.

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paulmilo
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Re: Starting Issues

Post by paulmilo »

Just purchased 4 new plugs yesterday (20 May) and will fit those shortly.

Interesting point running a cool cylinder as my number 4(right side on the display) def runs cool, however I put that down to airflow more than poor spark as EGT are all equal. The cylinders get progressively cooler reading the gauge left to right.

I’ll let you know how that goes once I have made the change. Did you use a modified plug socket? Mine has quite thick walls so I was going to grind down a section as it fouls as I place it over the plug.

I had not flown for a month and the battery was way down (11.7V) at start. Normally I don’t see less than 11.9. Barely turned the prop but still managed to start.

Cheers,
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