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Air leak engine wont idle

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Air leak engine wont idle

Postby albert611 » Fri May 09, 2014 9:00 pm

little help, have Poulan pro pp3516 35cc chainsaw was not running, carb. diaphragm was brittle, put kit in starts fine trouble is the idle, when you start it idles fine but when you rev it up takes forever to go back to idle and sometimes it will die, if I remember right this could be caused by air leak causing it to lean out, does this sound correct?
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Re: Air leak engine wont idle

Postby KE4AVB » Fri May 09, 2014 10:24 pm

albert611 wrote:little help, have Poulan pro pp3516 35cc chainsaw was not running, carb. diaphragm was brittle, put kit in starts fine trouble is the idle, when you start it idles fine but when you rev it up takes forever to go back to idle and sometimes it will die, if I remember right this could be caused by air leak causing it to lean out, does this sound correct?


With price of the Zama C1Q-W26B it would been better to just replace the whole carburetor. These stratus carburetors give more problems than are worth when it comes to rebuilding. There is a brass plunger in these carburetors that tend to wear out and is not available separate item even through they list a part number for it. I have tried ordering them before just get put on back order and a few months get cancelled by the vendor.

As for an air leak you would need to be running extremely rich for it run like this once the carburetor throttled back. Sounds more like a sticky throttle assembly. You did fully clean the carburetor didn't you? Also if you installed a new metering lever you did set it to the correct height? There several places in the carburetor intake system that can leak air.
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Re: Air leak engine wont idle

Postby bgsengine » Sat May 10, 2014 6:55 am

KE4AVB wrote:
albert611 wrote:little help, have Poulan pro pp3516 35cc chainsaw was not running, carb. diaphragm was brittle, put kit in starts fine trouble is the idle, when you start it idles fine but when you rev it up takes forever to go back to idle and sometimes it will die, if I remember right this could be caused by air leak causing it to lean out, does this sound correct?




As for an air leak you would need to be running extremely rich for it run like this once the carburetor throttled back. Sounds more like a sticky throttle assembly. You did fully clean the carburetor didn't you? Also if you installed a new metering lever you did set it to the correct height? There several places in the carburetor intake system that can leak air.

Or, leak gas.
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Re: Air leak engine won't idle

Postby albert611 » Sat May 10, 2014 10:11 pm

Thanks for your help, I did clean carb in ultrasonic and measured meter valve with zama tool. I was thinking of a cylinder leak rather than carb making it lean out, Think i'll check the carb price and go from there again thanks this site is great.
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Re: Air leak engine wont idle

Postby KE4AVB » Sun May 11, 2014 7:33 am

albert611 wrote:Thanks for your help, I did clean carb in ultrasonic and measured meter valve with zama tool. I was thinking of a cylinder leak rather than carb making it lean out, Think i'll check the carb price and go from there again thanks this site is great.

Meanwhile you can check all mounting bolts around the cylinder(4). They are on the bottom of the crankcase so they are easily accessible. Torque to 110-140 IN-LB. Check the cylinder/piston condition by removing the muffler and having a look inside. The intake assembly don't usually give problems but you check it mounting bolts((4) torqued at 40-50 IN-LB) ; of course, it can be damaged if you over torque the carburetor mounting nuts((2)torqued at 25-35 IN-LB)

These are the areas I usually check on any 2 cycle that I repair as there is a lot vibration involved. I only seen a couple sets of crank seal to be bad but they show up when the unit is running and is operated at various angle putting side pressure on the crankshaft.

All this might sound like a lot extra work but it time well worth especially if you find that cylinder/piston is heavy scored as this can be killer cost and labor wise.
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Re: Air leak engine wont idle

Postby Deere2me » Sun May 11, 2014 9:28 am

Yeah, pullin' the muffler to inspect the piston/cylinder is the first thing I do on just about any two stroke hand-held. Saves a lot of wasted time/effort.
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Re: Air leak engine wont idle

Postby albert611 » Sun May 11, 2014 9:34 pm

Pulled exhaust, ring, cylinder look good torqued case bolts checked linkage for sticking starts right up idles fine rev it up takes forever to idle back down looks like carb.
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