Jerry Cochran

Jerry Cochran

Well Known Member
Folks,

Hope some smart people here can help me. I flew from NW Oregon to Santa Rosa, CA today. First, I stopped along the way and upon departure, engine seemed rough while taxiing even tho I leaned it. Upon runup, seemd fine, so took off, cruised down here at 11,500, everything good. However, upon shutdown here, the engine did not want to quit, just kept chugging along firing about once per revolution. It being 90F deg here may have something to do with it, but I've been in hot wx before with Lycs and never saw this.

This is a Superior IO-360 fuel injected of course, horizontal intake.

Anyone with knowledge of this phenomenon? I've seen this in cars before fuel injection but never in an aircraft of any kind.

Thanks,

Jerry
 
Jerry Cochran said:
Folks,

Hope some smart people here can help me. I flew from NW Oregon to Santa Rosa, CA today. First, I stopped along the way and upon departure, engine seemed rough while taxiing even tho I leaned it. Upon runup, seemd fine, so took off, cruised down here at 11,500, everything good. However, upon shutdown here, the engine did not want to quit, just kept chugging along firing about once per revolution. It being 90F deg here may have something to do with it, but I've been in hot wx before with Lycs and never saw this.

This is a Superior IO-360 fuel injected of course, horizontal intake.

Anyone with knowledge of this phenomenon? I've seen this in cars before fuel injection but never in an aircraft of any kind.

Thanks,

Jerry
Click to expand...

Need more info... EI or mags? What FI system are you running? Do you have CHT readings?
 
Great engine... I have the same on my RV-8. If you have a RSA-5 or RSA-10 series Fuel Injector Servo from Precision Airmotive LLC (360) 651-8282 www.precisionairmotive.com.

There is a service bulletin PRS-107 that needs to be complied with...check your serial# from the Superior web site.

Check the mixture at the servo for proper ajustment. The tech guy's at airmotive are smart and really helpful.

Hope this will get you started in the right direction.

Zman.
 
My RV8 did the same thing. Ran rich, flooded easily and finally the idle cutoff wouldn't quite ....cut off. The same exact problem you had, ran crappy on the ramp and had to lean it out to idle. Ran great when the lever went forward.

I was ready take it to the shop. Then.......the problem went away. Works great now, weird huh? Probably some piece of debri stuck somewhere.
 
zman said:
Great engine... I have the same on my RV-8. If you have a RSA-5 or RSA-10 series Fuel Injector Servo from Precision Airmotive LLC (360) 651-8282 www.precisionairmotive.com.

There is a service bulletin PRS-107 that needs to be complied with...check your serial# from the Superior web site.

Check the mixture at the servo for proper ajustment. The tech guy's at airmotive are smart and really helpful.

Hope this will get you started in the right direction.

Zman.
Click to expand...

Yes, that SB was checked and does not appy, but looked at it anyway, no problem. I will check the mix control, just wish I was home with my tools.

Thanks, gotta luv this forum.
Jerry
 
Jerry Cochran said:
Yes, that SB was checked and does not appy, but looked at it anyway, no problem. I will check the mix control, just wish I was home with my tools.

Thanks, gotta luv this forum.
Jerry
Click to expand...

I would consider the FI, but as you've stated this problem just came to light. I take you did not have this problem prior to this event. Check the mag wiring and leads for proper connection. It's hard for a engine to keep trying to run without spark or extreme heat.
 
Remove the hose that goes to the flow divider. Put the mixture
control in idle cutoff and turn the boost pump on. Observe any
leakage at the hose you disconnected. Anything more then a drip every
couple of seconds, you need new mixture plates in the servo. If the
hose shows no leakage then you may need to get the flow divider
cleaned out, as something may be preventing the piston, in it, from
getting full travel.
Also, make sure any of the air bleeds on the fuel nozzles aren't
blocked. Do this by blowing into one end of the nozzle with your
mouth and your finger blocking the outlet. The air you blow in should
then come out the nozzles air bleeds. If one seems restricted, that
could be you problem.
If you have manual primer it could be leaking.
Good Luck,
Mahlon
"The opinions and information provided in this and all of my posts
are hopefully helpful to you. Please use the information provided
responsibly and at your own risk."
 
mahlon_r said:
Remove the hose that goes to the flow divider. Put the mixture
control in idle cutoff and turn the boost pump on. Observe any
leakage at the hose you disconnected. Anything more then a drip every
couple of seconds, you need new mixture plates in the servo. If the
hose shows no leakage then you may need to get the flow divider
cleaned out, as something may be preventing the piston, in it, from
getting full travel.
Also, make sure any of the air bleeds on the fuel nozzles aren't
blocked. Do this by blowing into one end of the nozzle with your
mouth and your finger blocking the outlet. The air you blow in should
then come out the nozzles air bleeds. If one seems restricted, that
could be you problem.
If you have manual primer it could be leaking.
Good Luck,
Mahlon
"The opinions and information provided in this and all of my posts
are hopefully helpful to you. Please use the information provided
responsibly and at your own risk."
Click to expand...

Mahlon,

Thanks so much, I was hoping you might weigh in. No manual primer and engine ran beautifully in cruise for 2.5 hrs with normal EGT's and CHT's. Do you suppose this is mainly an issue at idle? That's the only time I noticed symptoms. This engine is only a year old with 100+ hrs. Wouldn't it be unusual to need new mixture plates so soon?

Regards,

Jerry
 
Steve,
The newer style mixture plates are not lappable. They are coated with a coating that should keep them from getting scored but they still do get scored at times.
Jerry,
If they get scored it's because they got something in there to score them, not because they wore. So total time on them isn't really an issue, it just that they might have gotten some dirt in there and gotten scored and then they don't seal against each other the way they should. Do the test and see what you get for results.
Good Luck,
Mahlon
"The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."
 
Mahlon,
Thanks for the info.

My identical problem resolved itself. Would 'working' the mixture back and forth while ramp running have a chance of resolving this one as well??

Steve
 
Steve,
Not normally, as far as the servo goes. Maybe you were side loading the mixture control arm or the valve wasn't seating for some other reason and it "readjusted" itself with use. It would be possible to get something in the flow divider that would make the engine not shut off and then if that flushed out, it would fix itself.
Good Luck,
Mahlon
"The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."
 
Update

mahlon_r said:
Steve,
Not normally, as far as the servo goes. Maybe you were side loading the mixture control arm or the valve wasn't seating for some other reason and it "readjusted" itself with use. It would be possible to get something in the flow divider that would make the engine not shut off and then if that flushed out, it would fix itself.
Good Luck,
Mahlon
"The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."
Click to expand...

A very nice A/P at Kaiser Air in Santa Rosa helped me with it. Checked the plugs and timing first thing, cleaned fouled plugs, timing good. Reinstalled and I launched for home after an uneventful full power runup. Stopped for fuel 5 min up the road in Healdsburg, where rough idle/run on came back. After another 15 sec runup, I launched for home, engine ran very normally, perfect CHT/EGT's for 3 hours and landed.

Yesterday, took her for a test flight, no symptoms whatsoever. This is like Steve's story where it fixed itself. We'll see tomorrow when I have a 2 hr flight out and back.

Thanks all, for the help. Gotta luv this group.

Jerry
 
Try adding throttle

Jerry Cochran said:
Folks,
.....However, upon shutdown here, the engine did not want to quit, just kept chugging along firing about once per revolution. It being 90F deg here may have something to do with it, but I've been in hot wx before with Lycs and never saw this. ....
Thanks,

Jerry
Click to expand...

Just went through this exact same thing a few weeks back in my airplane.

A lot of good input form this site, but the one that was correct in my case:
-Push the throttle in a bit (higher RPM) before pulling the mixture.

The argument was that high density altitude due to heat was allowing the engine to stay barely alive on a lot less fuel. Opening the throttle causes additional leaning.

Anyway, this totally solved my problem.
 
If the engine runs on and refuses to quit, open the throttle (with the mixture in ICO), the engine will die straight away. Then figure out why a small amount of fuel is leaking into the cylinders using the tests described by Mahlon.

Pete
 
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