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
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..
Dave Calkins liked this post
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..
Originally Posted by behindpropellers
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.
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.
Last edited by OLDCROWE; 11-13-2017 at 06:50 AM.
Remember, These are the Good old Days!
Thanks Kirby!
This is standard procedure for ALL engines for determining idle mixture setting, not just the big Continentals.
NX1PA
Had an IO-520 in a C210 that I had to clean the injectors every 100 hours or it would hesitate like that.
This is the screen in the fuel control unit.
Yuck, I hate it when a filter does its job!This is the screen in the fuel control unit.
Remember, These are the Good old Days!
What the heck is coming apart?
Steve Pierce
Everybody is ignorant, only on different subjects.
Will Rogers
Clean recheck. Repeat, repeat
Maybe, some line guys fleece hoodie...
Remember, These are the Good old Days!
I doubt it, several other screeens prior to that one that would catch a line guy's hoodie.
Steve Pierce
Everybody is ignorant, only on different subjects.
Will Rogers
Looks like a Scotch Brite pad?
Glenn
"Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"
I'm leaning toward pulling the whole injection system off and sending it in for IRAN....
Thoughts?
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?
Remember, These are the Good old Days!
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?
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.
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...60348510651941
Remember, These are the Good old Days!
HA!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.
Last edited by OLDCROWE; 11-28-2017 at 12:14 PM.
Remember, These are the Good old Days!
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...
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.
Cessna Skywagon-- accept no substitute!
Drained the tanks and I am starting there....should be interesting.
Tim
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
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