QuestionQUESTION: I have a poulan 3400 chainsaw that I have used on and off for many years. I tried to start it this time with a small shot of ether as it had not been used for several years but stored with no gas as usual. It fired once as a teaser but then only maybe once a day just to not let you throw it away. I have tried to think of everything but am missing something that is stopping this engine from running. The compression is about 120#. It will not run with muffler/arrestor on or off. The spark looks good when plug is held against cylinder and pulled through. It has a solid state magneto that has been set to the fly wheel. I also thought maybe the flywheel shear key was broken and the timing was off but pulled it and it was perfect. The carburetor gaskets/diaphragms seem to be clean and flexible. New fuel with a hair less oil than required for better ignition for now. I have tried the ether, lighter fluid inside cylinder and gas in carburetor. It has of course become flooded and then dried our coyly. and plug. Everything is cleaned and looks to good to discard the unit. It is possible the carburetor could have some kind of problem but it should at least run a second or two on gas squired directly in unit. I also have no way to gauge strength of spark is absolute terms but it looks good enough blue to start engine although it is not jumping to my arm as I hold the plug against unit to test. I have used this for many trees and do not want to part with it now. What am I missing? Thanks.
ANSWER: Hello Thomas:
A Chainsaw is the Hardest Engine to Start with Gas or Starter Fluid. You can Easily Flood the Engine. Remove, Disassemble and Soak the Carburetor Overnight in Carburetor Cleaner (I Use Gunk). I have Found that Most People can Use a Breakdown/IPL and Disassemble the Carburetor Enough for Proper Cleaning. You Only have to Remove the Bowl, Float Pin, Float (if Applicable) and Needle Valve and Any Adjustment Screws that Go Into the Carburetor Body. The Welch Plugs Do Not have to be Removed. Then Soak the Carburetor Body and Parts in a 1 Gallon Can of Gunk Carburetor Cleaner Overnight. The Can has a Parts Tray Inside it for the Small Parts. Once the Carburetor and Parts are in the Cleaner, you can Replace the Lid for Safety and to Prevent Accidental Spillage. Then Blow Out the Passages with Compressed Air. Install New Parts if Required. Here are some Diagnostic Instructions to Do on the Trimmer/Chainsaw to Locate the Hard/Not Starting Problem. 1- Check the Spark. If Not Firing, then Replace. 2- If the Plug is Firing, then First, Remove the Muffler and Check for Blockage in the Exhaust Port and the Muffler. Check the Spark Arrestor Screen in the Muffler, too. 3- If these are Clear, then Pour a Small Amount of Fuel Mix Into the Carburetor Throat with the Throttle at Full. With the Throttle Still at Full, Try to Start the Engine. If the Engine Starts and Quits, Check the Fuel Filter and Lines. If these are Good, then Remove, Disassemble and Soak the Carburetor Overnight in Carburetor Cleaner (I Use Gunk). I have Found that Most People can Use a Breakdown/IPL and Disassemble the Carburetor Enough for Proper Cleaning. You Only have to Remove the Bowl, Float Pin, Float and Needle Valve and Any Adjustment Screws that Go Into the Carburetor Body. The Welch Plugs Do Not have to be Removed. Then Soak the Carburetor Body and Parts in a 1 Gallon Can of Gunk Carburetor Cleaner Overnight. The Can has a Parts Tray Inside it for the Small Parts. Once the Carburetor and Parts are in the Cleaner, you can Replace the Lid for Safety and to Prevent Accidental Spillage. Then Blow Out the Passages with Compressed Air. Install New Parts if Required. Set the Air Mixture Screws as Follows; All the Carburetor Adjustments are the Same for Lawn Mower and Trimmers. There are Several Location for the Air Mixture Screws. The Idle Air Mixture Screws are Usually Located at the Top of the Carburetor Bowl and the Top of the Carburetor Body. If the Main Air and Idle Air Mixture Screws are Side by Side on the Side of the Carburetor, then the Idle Air is the Farthest from the Engine. The Main Jet Air Mixture Screw is Located in the Bottom of the Carburetor Bowl or Beside the Idle Air Screw on the Side of the Carburetor Body. Some of the Older Model Carburetors have the Main Jet Mixture Screw Straight in from the Top of the Carburetor Body (this is Rare anymore). If you have Cleaned the Carburetor (Disassembled and Soaked Overnight in Carburetor Cleaner (I Use Gunk). Then Blow Out the Passages with Compressed Air and Install a New Kit if Required. Now Setting the Air Mixture Screws: ****Turn the Idle Air and Main Air Mixture Screws In Until SNUG **Don Not Jam** Then Reverse Both Screws 1 1/2 Turns. Holding the Throttle Full Open, Start the Engine. Turn the Main Air Mixture Screw Clockwise Until Proper Revs are Obtained. Occasionally you May have to Turn this Counter Clockwise to Achieve the Proper Revs. Now Allow the Engine to Idle. Set the Engine Idle Screw (Not Idle Air) so the Engine will Stay Running if Required. Now Set the Idle Air Mixture Screw so there is No Hesitation when Throttling from Idle to Full Throttle. Reset the Engine Idle if Required.**** 4- If No Fire at the Plug, then Remove the Coil Shut Off Wire from the Kill Switch. Check for Fire. If No Fire, then Remove the Blower Housing and Remove the Ground Wire from the Coil. Check for Fire. If Still No Fire, then the Coil/Ign Module is Bad. 5- If there was No Response from the Engine When the Fuel Mix was Poured Into the Carburetor Throat, then Check the Compression. 6- If the Engine has Compression, Fuel and Spark, but Still Does Not Run, then Check the Flywheel Key. It May be Damaged or Sheared and has the Plug Firing at the Wrong Time During the Power Stroke (compression). If you Hit a Snag or this Does Not Correct the Problem, I am Here if You Require More Assistance. Hope this Helps. Let me Know What Happens, Please. May the All Mighty Bless You and Yours. Thanks.
Good Luck
Respectfully
John
PS: I am Allowed to Answer 10 Questions a Day. If you See I am Maxxed Out, then Try Submitting your Question at or Just After 8pm EST (US). My New Day Starts then. Thanks.
Respectfully
John
---------- FOLLOW-UP ----------
QUESTION: I did most of the things your form response suggested. I have a flat diaphram type carb with not float or needle and seat. How can I tell if the solid state ignition module is putting out a strong enough spark or if it works at all is it ok? It seems to have a tough time firing on the first couple of pulls and then it floods the plug. How would I know if the spark is strong enough? It tries to fire first thing once in a while but only once and then it is done and wet. The module of course is quite expensive and somewhat hard to find for an old unit. The spark seems to be consistant when the plug is held against the cylinder. I don't know how to tell if it is strong enough or if that could be a possible problem. I never really paid attention to the spark when it was running
AnswerHello Again Thomas:
The Carburetor Instructions are for Most Carburetors. There is a Needle and Seat in All Carburetors. The Diaphragm Operates the Needle in a Chainsaw Carburetor. If this is Not Operating Properly, then the Carburetor Get Too Much Gas and Floods. If the Exhaust Port and Muffler are Clear, then the Needle Valve in the Carburetor is Set too High and Allowing the Carburetor to Flood. Slightly Bend the Needle Tab to Lower the Contact with the Diaphragm. If you Hit a Snag or this Does Not Correct the Problem, I am Here if You Require More Assistance. Hope this Helps. Let me Know What Happens, Please. May the All Mighty Bless You and Yours. Thanks.
Good Luck
Respectfully
John
PS: I am Allowed to Answer 10 Questions a Day. If you See I am Maxxed Out, then Try Submitting your Question at or Just After 8pm EST (US). My New Day Starts then. Thanks.
Respectfully
John
