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post #1 of 4 (permalink) Old 03-25-2019, 11:31 AM Thread Starter
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Stihl 011AV Pops but won't run

Hello everyone,
I have a Stihl 011AV in the shop and am perplexed. The engine will pop and run for a short while (about 3 seconds) when I place my thumb over the venturi (cover and choke are off while I'm working on it).
New fuel filter and line
Took carb apart and cleaned it 3 times (adjusting H and L make no difference to this problem)
3 different spark plugs
Muffler is unclogged and clean
Fresh Stihl 92 octane gas mixture

I'm stumped. I swear its a fuel pick-up problem. On another site Stihl talks about the Reed valves. Is that the contraption under the carb? If those gaskets are bad will that prevent the carb from sucking up the gas from the tank? Looking for suggestions/help.

Tango standing by.....

Tango (Tom)
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post #2 of 4 (permalink) Old 03-25-2019, 10:08 PM
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Originally Posted by Tango View Post
.... I swear its a fuel pick-up problem. ...

Is that carb one with both an inlet and an overflow vent back to the tank? If it is, any chance you have the fuel lines reversed?


I did just that on my leaf blower after replacing the fuel lines. Had me doing a lot of until for grins and giggles I swapped them and then it ran fine.

Mark - 2002 John Deere LT150H

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post #3 of 4 (permalink) Old 03-26-2019, 11:41 AM
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Have you checked compression? Two strokes need BOTH good compression and vacuum to run correctly. Could be a vacuum leak at the crankshaft seals or anywhere else a gasket has failed.


Have you looked through the exhaust port for scoring of the piston/rings and cylinder walls? If you do have reed valves, weak, cracked or bent ones will cause your problem.

Experience is something you don't get until just after you need it.
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post #4 of 4 (permalink) Old 03-28-2019, 02:08 PM Thread Starter
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Thanks Grunt,
Had my helper check compression and told me it was good. I rechecked it and its only at 60 psi. I think that is the culprit!

Tango (Tom)
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post #5 of 4 (permalink) Old 04-01-2019, 10:22 AM Thread Starter
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Final note on this Stihl 011AV:
After determining compression was a bit low I tore into the engine and discovered ring, piston and cylinder were in pristine condition. So looked a little closer and notice the slightest tear in one corner of the head gasket. Filled it in with some gasket goop and put everything back together. Let it sit and set up for a bit then did another compression test. Back up over 90 psi!. Spark plug installed and voila....it idles now. After tweaking H and L the machine is running good and back in the hands of the customer.

Thanks again Grunt!

Tango (Tom)
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