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C-90-12F Engine sputters (quits)on takeoff

D

Dan Gervae

FRIEND
Upper Peninsula of Michigan
I was doing splash and dashes in my T-Craft on floats tonight and twice it quit on takeoff....I'd be on the step...full power and rotating...seemed worse when I rolled it onto one float....I leveled off and pulled the carb heat on the last sputter and it cleared up and ran so I could get home....I took the bowl off and there was a little bit of crud in there...I was thinking carb ice but I was using carb heat on my approaches....It did start running again when I pulled the carb heat...I flew it home with the carb heat on.....I pulled the fuel line and that was okay....I did notice the fitting in the back of the Stromberg was not as tight as could be....it appears that in order for the fuel line to clear the Hanlon Wilson Exhaust Can...the previous owner left it back an eight turn ???? Any suggestions from you guys on this....I'm afraid to takeoff untill I find out what the heck happened.....One more thing confused me....I pulled the fuel valve off and when I tried to drain the bowl...gas would barely dribble out....put the fuel back on and she rushe=s out good....I'd have thought that a full bowl would drain faster.
 
Dan Gervae said:
I was doing splash and dashes in my T-Craft on floats tonight and twice it quit on takeoff....I'd be on the step...full power and rotating...seemed worse when I rolled it onto one float....I leveled off and pulled the carb heat on the last sputter and it cleared up and ran so I could get home....I took the bowl off and there was a little bit of crud in there
Since you found some crud in the bowl, the symptoms which you describe are indicative of crud/water in the carburetor bowl. When you tipped the carburetor on rotation and lifting one float water/crud will flow into the main jet and get sucked into the engine. Pull the plug in the back of the carburetor and let some fuel run through to flush it out.

One more thing confused me....I pulled the fuel valve off and when I tried to drain the bowl...gas would barely dribble out....put the fuel back on and she rushe=s out good....I'd have thought that a full bowl would drain faster.
Click to expand...

With the fuel valve off there is no way to replace what you are trying to let out. The valve needs to be open for the free flow.
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Click to expand...
 
try going full power before removing carb heat...

When I owned a t-craft, it would build ice all the time, all power settings :crazyeyes:
 
Another thing to check is your primer. I have had a similar experience happen and it was primer related. Just a suggestion.
WW
 
If it were the primer ....would it only happen at high angle of attack???Would there be any symptoms to look for....the primer seems to function ok....I'll check all of these out....I appreciate you guys responding.....If anyone else has suggestions..I'm all ears.
 
Sorry, a bail in a Piper muffler prevents a broken flame tube from blocking the outlet with the resulting engine shutdown. Good luck. Jim
 
I had a similar problem 2 years ago. End result was worn valve springs. Occured when engine was under load. At first, any change would clear the problem (carb heat, power setting, unloading). An easy and relatively inexpensive fix.
 
I used to get severe carb ice on climb out with my O-200 on a regular basis. Usually started about the time I was 200 ft AGL. Especially on cool humid spring and fall mornings.
 
Did you increase the size of the fuel lines when the C90 was installed. If i remember right the stock Tcraft has 1/4" lines and i doubt thats enough to feed a C90.
 
Well, it's been a year and the exact same thing happened yesterday under the same conditions....it's hot out, humid...and it only sputtered when I rolled it onto one float and pulled back to rotate.....I leveled off and it cleared.....landed, tried again, same thing. I leveled off, it cleared so I climbed to 4000 feet above the lake and just flew around. I landed, step taxied, no problem....rotated to left float,then pulled it off and blah....it almost quit....leveled off and it cleared. I do have 3/8" fuel lines for the extra flow.....I am burning Mogas, so I was wondering about vapor lock, but the change in pitch and roll is the only thing that causes the sputter...>I'll try draining the bowl....it seemed to work last year. But I did so many other things at the same time I could not definiately say what solved the problem.....the worn valve spring post has me thinking....could it be under the most extreme load in the rotation phase of takeoff?....I'd have thought the plow to step phase would cause the greatest lug. Perplexed.
 
Probably already mentioned, but carb float level? How about in uncoordinated flight to mimic rolling up on one float?
 
There are 2 recent articles in Cub Clues on the Stromberg carb, issues # 162 and 164. One discusses a recently discovered common fuel bowl problem, a mis-machining of the main jet seat and the second discusses needle/seat and other common problems. If you suspect a problem with your carburetor I recommend reading them to save yourself some time. Send me a PM with an email, I would be happy to scan and email them for you. Jim
 
This may be a long shot. Is it possible that the carburetor float is moving around (worn float hinge or twisted float?) and when tilted hangs up closing or restricting the needle valve thus less fuel in the bowl?

What happens when you take off straight ahead without lifting one float?

I can not imagine vapor lock only causing a problem when rolling up on one float.
 
Don't fool around. Pull the carb immediately and order an overhaul kit from El Reno Aviation. Check the float to see if it has any gas in it collecting via a leak. Overhaul per spec with the overahaul kit. Make sure the float height is correct and set it on a bench with the proper head pressure (we use a piece of surgical plastic tube to do this). Read the Cub Clues on the Stromberg, too, as it has some useful advice about setting the float height, etc.

Frankly, it sounds like a float hangup, which means a worn needle pivot thingy holder. It doesn't take much wear to hang it up. Fortunately it is simple to replace and it is included in the overhaul kit. It could also be that other nasty bugaboo--a leaking float. If you find a leak in the float, solder it. Then leave it in gas (not water) for 48 hours to see if it is still leaking.

At the end of the day the Stromberg is a very simple, relatively inefficient tractor carb that can easily be overhauled. Just follow the instructions and set the metering height, head pressure correctly, etc. Perhaps Jim can post the Cub Clues scans on this thread for us.
 
You could also ditch the stromberg and put a marvel knock-off on....It actually has an accelerator pump.....
 
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