Hard starting

[drstephensugiono]

I’ve had my money bravo for 26 years, and it is always easy to start, weather call or hot days. Lately it’s difficult to start when cold. My normal procedure is full Rich press my throttle in for about 5 to 6 seconds to prime, then it will start right up with in a few cranks. Now I would do the same procedure then it would crank over and over and over in and not start. No I wonder if it’s too rich and flooded or I’m not priming enough?! Before I would prime after like about 3 to 4 seconds the buzzing of the fuel pump goes to a different tone when pressure is applied, now it is the same tone no matter how long I prime

 

 

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[carusoam]

Sounds like....

1) Changes in fuel pump sound indicates it is not working the same now as it used to...

2) Chances are... it no longer delivers the same FF that it used to...

3) as stuff wears... the FF is probably less than what is needed...

4) do you get a decent FF reading while priming? (Has it changed?)

5) You can always add a few more seconds of prime... if it starts... you have a hint of what needs to be fixed...

6) If it doesn’t start... you are still in the zone of too much or too little... so flood it... then proceed to flooded start technique...

 

7) Some long Body electric fuel pumps have two electric pump switches... Hi and Lo... both operate the same pump.... the pump controller has a tendency to fail and operation on Lo may not work out so well... it struggles to deliver... not enough fuel over the same time...

Congrats on the 26 years of Bravo ownership!

I only have 20 years of Mooney ownership....  C & O...

PP thoughts only not a mechanic...

Best regards,

-a-

[LANCECASPER]

14 hours ago, drstephensugiono said:

 

I’ve had my money bravo for 26 years, and it is always easy to start, weather call or hot days. Lately it’s difficult to start when cold. My normal procedure is full Rich press my throttle in for about 5 to 6 seconds to prime, then it will start right up with in a few cranks. Now I would do the same procedure then it would crank over and over and over in and not start. No I wonder if it’s too rich and flooded or I’m not priming enough?! Before I would prime after like about 3 to 4 seconds the buzzing of the fuel pump goes to a different tone when pressure is applied, now it is the same tone no matter how long I prime

 

 

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What spark plugs are you using? If they are CHAMPION have you tested the resistance lately? Fine wire TEMPEST seem to start easier and run smoother.

[Davidv]

I also assume you’ve seen the chart in the POH that shows seconds of prime vs outside air temp?  When it’s cold the priming seconds go up by a fair amount.

[PaulM]

When my Bravo went from easy to start via the standard procedure, to troublesome, to nearly impossible, it was that the points on the left mag (< 100 hours)   were loose, and it needed a field rebuild.

The indicator of that problem is that it ends up starting after a long crank when you give up and release the starter, which then un-grounds the right mag and it can now fire and run.    The loose points were only indicated during starting with the impulse coupler.. it would mag check fine once I got it started. 

[KB4]

As @LANCECASPER said start with the plugs.  Use this $25 cleaner.  (get the proper media)  https://www.amazon.com/Pneumatic-Spark-Plug-Cleaner/dp/B004SBBNX0/ref=asc_df_B004SBBNX0/?tag=hyprod-20&linkCode=df0&hvadid=241994092016&hvpos=&hvnetw=g&hvrand=13066867746139269821&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9067609&hvtargid=aud-799727667774:pla-555836672540&psc=1

See if that helps, if not, it has to be fuel delivery issue. 

[PaulM]

7 hours ago, KB4 said:

Use this $25 cleaner.  (get the proper media)

I will say, I thought it was the same thing, and had the plugs cleaned and convinced myself that it started better afterwards, but mine continued to get worse, finally to the point where I just got it started to fly to maintenance and they found the bad mag. 

The plugs were probably cleaned at annual.. when was that?.. if recently it is unlikely to be that. 

[drstephensugiono]

Just had annual last month. I think pump is lazy. I will
Try priming longer


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[drstephensugiono]

Thank you guys!  Just to report that my mechanic found that the fuel pump delivers 40-50 psi and when activated the panel pressure gauge to high green range. Got to a point that we couldn’t start it.  He found the right Mag not firing.  Sent both sir service.  Got it back today and he’s installing now.  Will report tomorrow!

[carusoam]

Great follow-up, Stephen!

Any idea how many hours were on the mags..?

Best regards,

-a-

[Jetlag]

I bet it is your mag. The left one. 

[drstephensugiono]

Great follow-up, Stephen!
Any idea how many hours were on the mags..?
Best regards,
-a-

I’ll asked ... he told me but I forgot


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[drstephensugiono]

I bet it is your mag. The left one. 

Your are close, it’s the right one!


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[carusoam]

Left mag is often the one responsible for adjusted timing for the start process...

Might be different for the Bravo?

@donkaye would be a great resource for Bravo and electricity questions... 

Best regards,

-a-

from the internet...

”Many of the well known types of SEPs & MEPs are fitted with similar Lycoming engines. Yet some manufacturers' POHs (eg Piper) mostly state that engines should be started up with both mags on, while other manufacturers (eg Grumman) usually say start up with only the left mags on.”

“Summing it up, if your airplane has a Shower of Sparks system, or you're flying a Lycoming-powered Travel Air, 56TC or Machen Bonanza, start on the left magneto only. If it has impulse couplings start on both magnetos.”

[drstephensugiono]

Started the plane, started right up like it used to !!!!


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[PaulM]

On the Bravo the left mag has the impulse coupling and is the only one active during the start.  The key switch grounds the right mag in the start position. 

This is shown on the wiring diagram as an external jumper between the E & U terminals on the 98-2273 switch. 

So, I would suspect that both mags had problems, just different ones. 

[drstephensugiono]

On the Bravo the left mag has the impulse coupling and is the only one active during the start.  The key switch grounds the right mag in the start position. 
This is shown on the wiring diagram as an external jumper between the E & U terminals on the 98-2273 switch. 
So, I would suspect that both mags had problems, just different ones. 

I don’t know, but I’m
Glad it’s fixed!


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[carusoam]

Something to consider if it happens Again, 20 years from now...

nevermind, we can discuss it again then...   

It does appear to be two different mag problems...
 

See if you have data for what failed or got replaced...

And how many hours were on them...

Other People have a tendency to remember these kinds of things... it’s natural for them...

The MS collective memory is really impressive ... 

Best regards,

-a-

[drstephensugiono]

I asked the mechanic, he said Mags were  replaced 1000 ago,  hhmmm 

[mike_elliott]

1 hour ago, drstephensugiono said:

I asked the mechanic, he said Mags were  replaced 1000 ago,  hhmmm 

The underwhelmingly designed slick mags on the Bravo need to be addressed every 500 hrs if not sooner. They have these plastic parts in them that tend to get brittle with heat, may shed some teeth and try to kill you on take off.Stay on top of this weak point of otherwise a very stout engine

[Davidv]

2 hours ago, mike_elliott said:

The underwhelmingly designed slick mags on the Bravo need to be addressed every 500 hrs if not sooner. They have these plastic parts in them that tend to get brittle with heat, may shed some teeth and try to kill you on take off.Stay on top of this weak point of otherwise a very stout engine

I decided to have mine inspected after 250 hours because of a previous incident.  While the parts were still in good condition the internal timing had slipped by a fair amount on the right mag so we at least got that corrected.  Some experts here will tell you that some parts even start to go at 250 hours...

[LANCECASPER]

4 hours ago, drstephensugiono said:

I asked the mechanic, he said Mags were  replaced 1000 ago,  hhmmm 

Wow, you may have a new record on Slick 6300 series mags. Once there are two good, known working mags I like to make sure that I never send both off at the same time for an inspection. Staggered maintenance on redundant items is not a bad idea so the same person making the same mistake doesn't lead to double failure. As an example, I had to go with a new mag in late 2015 for the right side, the left was fine. In early 2019 I sent off the left one early for the inspection, etc. 

What's frightening is that any of your annuals in the last 500 hours haven't caught the 500 hour inspection was past due - what else did they miss? Here's an important one to check: I would have someone carefully check your exhaust system. If your tail pipe transition goes, the hot exhaust goes directly through the firewall and into the cabin, killing the occupants. A trusted mechanic found this soon after I bought my airplane . . . . after a "thorough" pre-buy.

 

 

[drstephensugiono]

Wow, you may have a new record on Slick 6300 series mags. Once there are two good, known working mags I like to make sure that I never send both off at the same time for an inspection. Staggered maintenance on redundant items is not a bad idea so the same person making the same mistake doesn't lead to double failure. As an example, I had to go with a new mag in late 2015 for the right side, the left was fine. In early 2019 I sent off the left one early for the inspection, etc. 
What's frightening is that any of your annuals in the last 500 hours haven't caught the 500 hour inspection was past due - what else did they miss? Here's an important one to check: I would have someone carefully check your exhaust system. If your tail pipe transition goes, the hot exhaust goes directly through the firewall and into the cabin, killing the occupants. A trusted mechanic found this soon after I bought my airplane . . . . after a "thorough" pre-buy.

 
 

Thank you for sending me the picture of the exhaust I will follow up and have them look at it thank you very much


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[carusoam]

Great follow-up Stephen!

We have gotten to learn a lot about mags this way... plastic gears in an ozone environment oxidize and get brittle... over the hours in use...

There is also a picture of a Bravo exhaust around here where the wall thickness erodes over time....
 

Thin enough to poke a hole in...

Like the broken weld, a cracked pipe before the turbo is very torch like...

Things to look for while in there...

PP thoughts only...

Best regards,

-a-

[drstephensugiono]

It is nice to learn from others with problems with Mooney bravo so we all can look at what we have and repair appropriately


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