How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Rick Your Own Question
Rick, Factory Authorized Trainer
Category: Small Engine
Satisfied Customers: 8057
Experience:  Outdoor Power Equipment technical trainer since 1990, covering eight states.
Type Your Small Engine Question Here...
Rick is online now
A new question is answered every 9 seconds

My McCulloch 14 inch bar 33cc chainsaw starts up and runs at

This answer was rated:

My McCulloch 14 inch bar 33cc chainsaw starts up and runs at medium to high speed, but even when warmed up, it quits at idle. I note there seem to be two adjustment holes in the front top of the handle, and I don't have the manual anymore. Any ideas? Thanks. PS Using fresh 2 cycle premixed non leaded gas, and oil bought from Home Depot. Also, a fresh plug, gapped to 025.

Hello, and thank you for choosing JustAnswer. I'll be helping you today and am committed to providing clear and concise answers to your question.


How old is this saw? What is the oldest fuel that's been in it? Was it stored with fuel over the winter? Are you using 40Fuel premixed fuel now? Can you tell me the model and serial number?

Customer: replied 6 years ago.
Thanks for your help. The info you requested is:
Model Number (off the plate) (NNN) NNN-NNNN07
Serial Number: 11-031965
Sticker on case says: MAC 3214 32 CC (Sorry, I said 33 cc.)

Fuel is from Home Depot called TRU FUEL 50 to 1, gas and oil. It was stored with the tank empty, except
with some STABIL, also run through the carb with the ignition OFF, prior to dry storage for the winter.
As I said, the plug was also replaced with .025 gap before winter, and the saw ran fine, though took a
number of pulls to start, plus a squirt in the plug of starting fluid. As I said, after doing the same, the
saw started up, ran at high speed with the chain moving. When it warmed up, I let off on the throttle trigger, and the saw would not keep running. It will restart with one or two pulls with the choke in as long as it is warm. I have always used regular 87 Shell gas, with Echo Brand 2 cycle oil, and Stabil, and never use fuel older than about 3 weeks. This premade fuel I referred to above, works great in my other
2 cycle power tools. Any other questions, please ask. Thanks!

Jeffrey Beals

You do a whole bunch better job than most. This time of year I always looks at a bit of plugging in the carburetor from stale fuel. This is usually the case since the government-mandated ethanol blends may be fine for cars, but they wreck havoc on small air-cooled engines and tend to break down rather quickly. These types of repairs are bout 70% of what we see come through the shops.


I think from your description you probably have just the opposite problem, since it was stored dry. Life is full of little trade-offs and dry storage while preventing the build-up of gums and varnsh will often cause the diaphragms to become brittle. As a first thing to check, I would pull the covers off the metering side and pump sides of the carb and see if the diaphragms are still soft and pliable.


Let me know, please and we'll contnue...

Customer: replied 6 years ago.
If it is okay with you, I will do it first thing. I am in Seattle, Washington, and it is getting dark here, since
we are "up north".

I will try and do what you ask, and reply to you. Again, many thanks, XXXXX XXXXX still wonder if the idle adjustment
is off. I haven't touched ANY of the apparent "screws".

If it was running well previously, unless the screws have been fiddled with, that's not usually the problem. Not saying for sure that it's not, but they usually don't move around in the case on their own. that's why I usually look at the other things forst unless I get information like the neighbor tried helping adjust it or some such thing.


I'm a bit jealous. I'm down in Central Cal and I sure miss Seattle. I used to go up there once a year to do dealer schools and I fell in love with your city. Wife and I have been talking a lot about moving there once the kids are out of school. I always loved the drive on I-90 going east from I-5 across the water toward Spokane, and Snoqualmie Falls is gorgeous! And your guy's coffee ain't half bad either....


Talk to you in the AM...

Customer: replied 6 years ago.
Good Morning.

The diaphragms appear to be soft and fairly supple. I neglected to mention that my late father, from whom
I got the saw may well have "fiddled" with the carb screws last year, prior to his passing. I am thinking
that may be the problem, but you are the expert. Any thoughts?

By the way, I live on Mercer Island, in the middle of Lake Washington with a magnificent view of the
Cascades, the Lake and Mt. Rainier on a clear day. I can also see a bit of Bill Gate's place, much of
which is buried into a hill. It is truly paradise. An old house my dad built in 1949, when NO ONE wanted to
live on Mercer Island. He was a Federal Agent, and therefore, did not make much money. The house and
3/4 of an acre of view property totalled $11,000. It is now about 100 times that amount. Little did he
realize......The property taxes of course, are withering.


Jeffrey Beals

Wow. Lucky...


Then I would certainly look at a carburetor adjustment at this point. Here's the procedure. You've already done some of these things, but I'll still post it to be complete.


Before adjusting the carburetor make sure the fuel is fresh and that your fuel filter and air filter are clean. Check the spark plug and replace if necessary. Check the spark arrestor screen, muffler and exhaust ports and clean of any excess carbon build-up.

Start the saw and let the engine warm up completely. Never adjust the carburetor on a cold engine.

While idling, turn the "L" screw clockwise all the way in until the engine makes a higher-pitched whine. Back the screw out one-quarter turn and note its position. Then turn it back counterclockwise until the engine starts running rough or dies. Turn the screw back one-quarter turn and note its position. Set the screw halfway between the two positions you noted. Listen to the engine and test throttle response. The rpms shouldn't be too high or too low, and it should accelerate properly.

Holding the throttle in the full throttle position, turn the "H" clockwise until the engine starts making a very high-pitched whine. Back the throttle off, and back the screw off one-quarter turn immediately, since overspeeding can quickly ruin the engine. Hit the throttle again and turn the "H" screw counterclockwise until the top speed starts noticeably falling off. Turn the screw clockwise one-quarter turn. Adjust the "H" screw in between these two noted positions. These positions are the lean and rich drop-offs, respectively. Listen very carefully to the engine for the best reponse to the throttle, indicating the mixture is neither too rich nor too lean.

Finally, you adjust the idle speed to just slower than when the clutch engages.

Customer: replied 6 years ago.
Are these the two "holes" at the top front? I want to make sure. Thanks!

Should be at the recoil side of the near the rear. About a quarter inch in diameter and about an inch apart. You may be able to see better by taking the top cover off.
Customer: replied 6 years ago.
One final clarification on the carb adjustment procedure you so carefully outlined. Since it is hard to start,
as mentioned, and needing a shot of starting spray in the new plug chamber, are there factory "DEFAULTS"
for each of the two carb settings to which you referred? I was thinking that maybe starting from the
factory "defaults" might make starting easier, and therefore, easier to adjust.
I'm a professional saxophone player, obviously NOT a mechanic, so thankyou for this final question on


Jeffrey Beals
Yes, gently tighten them until just seated. Be careful not to overtighten since it doesn't take much to damage the thin needles, then back them off 1-1/2 - 2 turns. This should at least get you started.
Rick and 4 other Small Engine Specialists are ready to help you