Wanted to cut out on landing

[paddydix]

Had something interesting happen today. Flew over to Wolf River to land on the grass, did the usual carb heat and pull some power off, but not all the way. As I made the decent on final I pulled the power back to idle,...and she tried to cut out on me. Gave it a little gas and it kept on running. Headed back to FYE after take off, which went smooth and everything seemed fine. Upon getting back to FYE again, carb heat in the pattern, pulled the throttle back ,...started to descend normally , turned to final , throttle to idle and again is started to die on me, again a tad of throttle and she kept on running. I am running ethanol free auto fuel in her right now. Could it have been a little carb ice? Even though the carb heat was on? Thoughts and ideas of things to look for appreciated.

[Howard Wilson]

Re: Wanted to cut out on landing

Could be carb ice. Did you clear it at all after you retarded the throttle? What was the temp and humidity? h

[paddydix]

Re: Wanted to cut out on landing

Temp was 81 F , humidity around 73 . Basically carb heat on, throttle to 1000 rpm...turn final and pull it back to idle. Has never done this before, so of course I'd like to get yall's input.

[Howard Wilson]

Re: Wanted to cut out on landing

How did it idle after you taxied back to the hangar/tie down, before you shut down? Was it rough for a few seconds after you increased the rpm while descending, then smoothed out? h

[paddydix]

Re: Wanted to cut out on landing

It seemed to run just fine when I put in the throttle just a bit. Really did not notice any rough running, well except when I pulled the throttle all the way back to idle. When I got it back on the ground I ran it up a few times and pulled throttle back and it acted a little rough at idle.

[M Towsley]

Re: Wanted to cut out on landing

Patrick,

Not sure if this is your problem, but mine actually died on final. It would run fine somewhere above 1,100-1,200, if I remember correctly. One of the small ports, that feed fuel at the lower throttle setting got blocked by some crap that somehow got past the gascolator filter. It re-started fine and ran fine but when I got back to my home airport it ended up wanting to quit below those lower rpm's. When I advanced the throttle past that point it ran fine. Cleaned the carb, replaced the gascolator screen and made sure the fuel line was clean. Haven't had a problem since. Even when flying when you move the throttle you can feel how the carburetor is running off different ports in the carb. Sure gets your attention.

[Pearson]

Re: Wanted to cut out on landing

Patrick,

A thousand RPM is where the Stromberg NAS 3A changes over from the idle circuit to the main. If it is dying at anything below 1000RPM something is wrong with the idle circuit. Seems odd that it isn't doing it while you are taxiing around. Maybe the angle during descent has something to do with it. Are you seeing any fuel leaking after shut down. If the float is out of adjustment, or the needle is not stopping the fuel flow, you may be running too rich at the lower RPMs. This has been brought up on this forum before. Maybe a search will turn up a solution. You can check the float level without taking the whole carburetor off. Once you get the cowl off, it only takes about 5 minutes.

[paddydix]

Re: Wanted to cut out on landing

Definitely something to keep in mind Marty. Hope to get her up soon, may have rain tomorrow . Thinking of putting some 100LL in the tank and just stay in the pattern with her for awhile. It could be my idle needs to be upped a bit ?

[paddydix]

Re: Wanted to cut out on landing

Richard no fuel drips at shut down.

[M Towsley]

Re: Wanted to cut out on landing

If it was fine before, then upping the idle may not be the answer. Temperature difference might have affected the mixture.

Richard, I knew it was somewhere around 1,000 or so. I wrote the details down, somewhere, on where it was cutting out. I will have to find them.

I have never seen any technique in checking float level on the plane. Stromberg instructions have the carb apart and measuring fuel level while running head pressure. I have done it many times, (pain in the behind), and tedious changing out gaskets under the seat. I am curious as to how it would be done on the plane.

[Pearson]

Re: Wanted to cut out on landing

If no fuel drips, the float needle and seat are doing their job. Or probably so. Sounds like you might have what Marty had, foreign object somewhere in the idle circuit. Still might be worth having a mechanic take the cowl off and remove the bottom of the carb to make sure the seat hasn't come loose from the body of the carb. That would let fuel leak in around the needle and seat and cause over rich running. I don't recall what the float setting is supposed to be, but a mechanic with any experience with these carbs can tell if the float is functioning properly with the bottom removed. If you go fly, ask someone to watch you around the pattern. Tell them to look for black smoke out the exhaust when you pull the power back. If they report black smoke, that is unburned fuel, ie running rich. If no black smoke and it still tries to cut out, I would suspect a clog in the idle circuit. That will mean taking the carb apart and blowing it out with air, or otherwise cleaning it.

[lawheelock]

Re: Wanted to cut out on landing

Had something interesting happen today. Flew over to Wolf River to land on the grass, did the usual carb heat and pull some power off, but not all the way. As I made the decent on final I pulled the power back to idle,...and she tried to cut out on me. Gave it a little gas and it kept on running. Headed back to FYE after take off, which went smooth and everything seemed fine. Upon getting back to FYE again, carb heat in the pattern, pulled the throttle back ,...started to descend normally , turned to final , throttle to idle and again is started to die on me, again a tad of throttle and she kept on running. I am running ethanol free auto fuel in her right now. Could it have been a little carb ice? Even though the carb heat was on? Thoughts and ideas of things to look for appreciated.

Patrick,
I don't know what primer you may have, but a non-locked or leaky primer or a fitting in the primer circuit might cause such symptons.
Something to check.
Larry Wheelock, BC12D N96179 not flying

[paddydix]

Re: Wanted to cut out on landing

I thought about the difference in temps, air was cooler today than it has been . Then I thought, well no changes in any settings have been made since I bought it in Oct. , and I was flying it in the cold of winter, and then all summer ....and temp did not seem to bother it. Larry I have one of the original primers, it was in and locked. (I get tickled at that old primer, seems like you pull it all the way out and push in and you put a half gallon of fuel in! LOL) I am leaning toward some kind of obstruction in the idle circuit. I hope I can get lucky and whatever it is works itself out of there ! I'll let you guys know how the pattern test flights go .

[Howard Wilson]

Re: Wanted to cut out on landing

I think Marty and Richard are on to it with the blockage. Had a problem with mine where it would idle and run up fine but when the tail came up on take off it would almost quit and run rough. Turned out to be a bunch of flaky crud in the gascolator screen. Not quite your issue but a bad batch of gas can clog it up..... h

[M Towsley]

Re: Wanted to cut out on landing

Patrick,

Chances are having whatever may have blocked the orifice work its way out is slim. Those holes are tiny so the carb will have to come off. While I had mine off I sent it off and had it gone over to make sure everything was ok. These are pretty simple carbs, but I did not want to experience that again. Turns out mine was a little on the lean side. It has, (knock on wood), run flawlessly ever since. I had mine gone through by KPS Airmotive.