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behindpropellers
11-12-2017, 11:06 AM
Chasing this right now:

IO-520A Rebuilt Mags and New Engine controls.

1. Idle is low.
2. When advancing throttle it stumbles before catching up.


Informed guess: Previous throttle cable was adjusted to give the correct idle RPM. Fuel flow is not up to spec on the low end.

Gauges go on the fuel system next week...

Tim

mike mcs repair
11-12-2017, 11:13 AM
yes step one, get fuel high & low pressure correct, to high end of range on high.(well at least for sea level)

get it to idle as low as it will stay running, if you got a good cam this can be down to ~350, you should see a little black smoke out of exhaust when mixture is correct at this low idle, not that you idle it that low always, but helps for landing..

35S
11-12-2017, 02:36 PM
Just just went through this on my 520. Sounds like your idle mixture is to lean. Do you get a small rise as you cut the mixer? If not, to lean. This will cause a stumble when advancing throttle from idle..
check your high and low fuel pressure, adjust idle and idle mixture. Then you should b good..



Chasing this right now:

IO-520A Rebuilt Mags and New Engine controls.

1. Idle is low.
2. When advancing throttle it stumbles before catching up.


Informed guess: Previous throttle cable was adjusted to give the correct idle RPM. Fuel flow is not up to spec on the low end.

Gauges go on the fuel system next week...

Tim

charlesf
11-12-2017, 02:50 PM
If I remember correctly, the manual I have says set the rpm at 1000. Slowly pull the mixture out to almost cutoff. As you lean, the rpm shud increase about 50 rpm, then decrease. This shud give you a quick idea of how to adjust the mixture.

OLDCROWE
11-12-2017, 08:04 PM
Clean the injectors, I use Hoppies #9 in an ultrasonic hot pot. Mine really hesitates and won’t come off idle unless you baby it if the injectors have more than say 250-300hrs since the last cleaning. Also if you are getting a little fuel drip out of the injection vent line after shut down the flow divider may need a rebuild, just had that done.

behindpropellers
11-12-2017, 08:50 PM
Thanks Kirby!

skywagon8a
11-13-2017, 06:38 AM
If I remember correctly, the manual I have says set the rpm at 1000. Slowly pull the mixture out to almost cutoff. As you lean, the rpm shud increase about 50 rpm, then decrease. This shud give you a quick idea of how to adjust the mixture.
This is standard procedure for ALL engines for determining idle mixture setting, not just the big Continentals.

Steve Pierce
11-13-2017, 07:31 AM
Clean the injectors, I use Hoppies #9 in an ultrasonic hot pot. Mine really hesitates and won’t come off idle unless you baby it if the injectors have more than say 250-300hrs since the last cleaning. Also if you are getting a little fuel drip out of the injection vent line after shut down the flow divider may need a rebuild, just had that done.

Had an IO-520 in a C210 that I had to clean the injectors every 100 hours or it would hesitate like that.

behindpropellers
11-27-2017, 02:38 PM
This is the screen in the fuel control unit. :evil:

33816

OLDCROWE
11-27-2017, 06:53 PM
This is the screen in the fuel control unit. :evil:

33816
Yuck, I hate it when a filter does its job!

Steve Pierce
11-27-2017, 07:53 PM
What the heck is coming apart?

mike mcs repair
11-27-2017, 08:22 PM
What the heck is coming apart?

Clean recheck. Repeat, repeat

OLDCROWE
11-27-2017, 08:52 PM
What the heck is coming apart?
Maybe, some line guys fleece hoodie...

Steve Pierce
11-28-2017, 07:26 AM
Maybe, some line guys fleece hoodie...

I doubt it, several other screeens prior to that one that would catch a line guy's hoodie.

cubdriver2
11-28-2017, 08:18 AM
Looks like a Scotch Brite pad?

Glenn

behindpropellers
11-28-2017, 10:06 AM
I'm leaning toward pulling the whole injection system off and sending it in for IRAN....

Thoughts?

OLDCROWE
11-28-2017, 10:21 AM
That’s more junk on the screen than I’ve seen in 5+years combined on mine. I’m with Steve, what’s coming apart or got in the system, as I understand the system that’s the last chance screen.

How long has it been since the last cleaning?

behindpropellers
11-28-2017, 11:05 AM
That’s more junk on the screen than I’ve seen in 5+years combined on mine. I’m with Steve, what’s coming apart or got in the system, as I understand the system that’s the last chance screen.

How long has it been since the last cleaning?

I'm going to call the last guy who did the annual and ask him about it. There actually is one more screen, in the fuel divider.

Any favorite continental fuel injection shops you guys recommend?

Steve Pierce
11-28-2017, 11:52 AM
from the Rolodex: ;)
Mike's Fuel Metering
9406 East 46th Street North
Tulsa, OK 74117
918-838-6217

Been a while since I did anything fuel injected but he was good to me.

OLDCROWE
11-28-2017, 11:56 AM
I'm going to call the last guy who did the annual and ask him about it. There actually is one more screen, in the fuel divider.

Any favorite continental fuel injection shops you guys recommend?

Mike's Fuel Metering in Tulsa, they did my flow divider a few weeks ago (very prompt) and I understand they do most of the big Tulsa engine shops work.

https://www.facebook.com/pages/Mikes-Aircraft-Fuel-Metering-Service/160348510651941

OLDCROWE
11-28-2017, 11:59 AM
from the Rolodex: ;)
Mike's Fuel Metering
9406 East 46th Street North
Tulsa, OK 74117
918-838-6217

Been a while since I did anything fuel injected but he was good to me.HA!

mike mcs repair
11-28-2017, 12:15 PM
since that filter is after gascolator & screen, I would say, start with the gascolator to determine the screen in it is not damaged, to have let all that by.... never seen that much downstream...

hotrod180
11-29-2017, 12:37 PM
I had the carb inlet screen (aka last chance filter) clog once in my old C170 ragwing.
This was downstream of both the screen in the gascolator and the screen in the engine-driven fuel pump.
Itty bitty red fibrous debris, looked like someone dropped a red shop rag in the fuel tank and it slowly dissolved.

behindpropellers
11-29-2017, 06:30 PM
I had the carb inlet screen (aka last chance filter) clog once in my old C170 ragwing.
This was downstream of both the screen in the gascolator and the screen in the engine-driven fuel pump.
Itty bitty red fibrous debris, looked like someone dropped a red shop rag in the fuel tank and it slowly dissolved.

Drained the tanks and I am starting there....should be interesting.

Tim

behindpropellers
11-30-2017, 09:39 AM
Pulled the gascolator last evening, not much in it as far as debris. Right header was clean. Left header had some water and gunk in it.

Tim