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Briggs-Fan, Small Engine Technician
Category: Small Engine
Satisfied Customers: 1265
Experience:  over 15 years experience in small engine repair, multiple certifications
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Re Husqvarna 3120xp (EPA) - s/n 05 0600041 Saw is in

Customer Question

Re Husqvarna 3120xp (EPA) - s/n 05(###) ###-####
Saw is in "like-new" condition; used very little. Purchased second-hand; original owner claims it is as he bought it new; nothing ever done to it.
The saw starts easily, idles nicely, has good acceleration and runs fine until it reaches 7,500 to 8,000 r.p.m. At this point the throttle is about 1/3 open and it is just starting to make a "four cycling" or burbling noise. As the throttle trigger is depressed further, this condition becomes more pronounced. At wide open throttle the r.p.m. is still under 9,000, smoke and raw fuel are blowing through the muffler and the saw sounds sick!
As pressure on the throttle trigger is eased off, the saw runs better and better until the
throttle is returned to about 1/3 open where it runs perfectly again.
1. Adjusting the fuel mixture with the low speed needle (no high speed needle on this
carb.). Adjusting made no difference at all.
2. Replaced the ignition module (503 9017 01) with new updated module (544 0188 01). This made no difference at all.
3. Checked muffler screen & exhaust port for carbon buildup - all O.K.
4, Checked decompressor valve for leaking - good
5. Removed carburetor and pressure tested needle valve. Disassembled carb. to
inspect needle valve lever height and condition of diaphragms; also looked for signs of
dirt & gumming. Carb. is just like new and clean as a whistle. Everything looks good.
6. Made sure air filter is clean.
7. Replaced spark plug.
8. Made sure flywheel magnets are O.K. and air gaps on ignition module are correct.
Submitted: 2 years ago.
Category: Small Engine
Expert:  Briggs-Fan replied 2 years ago.

Hi my name is ***** ***** welcome to just answer. Reading over what you have checked you have covered alot of the common problems . I know you removed and inspected the carburetor needle etc , but some times these carburetors need to be disassembled and boiled then sprayed out with carburetor cleaner. I personally use a ultrasonic cleaner at my shop and just had to boil a zama c1u k52 carb twice to get it to run right . So I would honestly try removing the carburetor, remove the gaskets , needle, low speed adjustment needle etc and boil it in a pot of water for 3 minutes or so then spray it out with Gumout carburetor cleaner.

Customer: replied 2 years ago.
Thank you for the advice re problem with my Husqvarna 3120. I think you are probably right;
this saw was idle for several years and could have gum deposits in areas where some fuel lingered after the saw was emptied for storage. Never heard of using boiling water for this;
good tip!Unfortunately, circumstances prevent me from working on this saw for next few days. Soon
as I can get back at it, I'll certainly try boiling that carb. (maybe put a new kit in it as well). I will
then get back to you re results. Hope this is O.K.Larry
Expert:  Briggs-Fan replied 2 years ago.
Larry sure that is no problem , just let me know how it goes when you get to it and if you have any questions etc feel free to contact me