Lawn mower pull back when I atempt to start it...

SOURCE: MTD Yardman push mower runs fine for awhile then cuts off.

Try buying a new plug first but if it continues then I would say that there is debris in the carb.

SOURCE: yard man gas push mower starts but wont stay running

Hello jusapup68:

>>Did you Soak the Carburetor when you Cleaned it?
>>If No, then the Carburetor can Still be the Problem.
>>Does the Engine Start and Quit if you Pour a Small Amount (1/4 oz of Gas into the Carburetor and Try to Start the Engine?
>>If Yes, then Soak the Carburetor Overnight.
>>The Following is a Basic File I Made for Cleaning Carburetors. Any Input is Appreciated. Even though the Carburetor Looks Clean, the Internal Passages May be Restricted with Varnish that Gas Causes to Build Up over Time.
>>Spray Cleaners Remove this Varnish in Layers, so Soaking is the Only Sure Way to Remove ALL this Varnish.
>>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 (if Applicable), Float Pin (if Applicable), Float (if Applicable), Needle Valve.
Remove Any Adjustment Screws that Go Into the Carburetor Body. The Welch Plugs Do Not have to be Removed.
>>If you are Able to Remove and Disassemble the Carburetor and Keep the Gaskets Intact, then Usually these Gaskets can be Reused. The Only Parts you May Need to Replace is the Needle Valve.
>>The Float Needle Usually is Not Replaced Unless it is Not Operating Properly (the gas flow not shutting off and the carburetor is Flooding). Do Not Remove the Main Nozzle. This is a Pressed Fit and Removal is Not Required for Cleaning. Soaking and Blowing the Carburetor Out After Soaking will Clean the Nozzle.
>>Once Disassembled, 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.
>>***(Do Not Use High Pressure Air for the Zama Carburetors, they have Check Valves for the Primer and these are Usually Blown Out of the Carburetor if Not Careful. Allow the Zama Carburetor to Set on a Drip Pan and Dry)***.
>>****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 Nearest 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 **Do 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.****
>>If This Carburetor has a Single Air Adjustment (Except Tank Mounted 9200 and 100900 Engine Model Carburetors), Use the Section Above that Pertains to Full Throttle RPM Air Mixture Screw and then Adjust the Screw if Required to Eliminate Any Hesitation when Throttling from Idle to Full Throttle.
>>For the 9200 Model Tank Mounted Carburetor Adjust the Air Mixture Screw Full In, then Reverse 1 1/2 Turns. Set the Throttle Lever to Full Throttle and Start the Engine.
>>Now Carefully Use 1 Finger and Open the Throttle Plate and Over Rev the Engine Slightly. If the Engine Over Revs and Does Not Struggle to Over Rev, then the Carburetor is Set. If the Engine Struggles to Over Rev, then Turn the Adjustment Screw In 1/4 Turn and Repeat the Over Rev Test.
>>If you Adjust to 1/2 Turns In and the Engine Still Struggles to Over Rev, then Return the Adjustment Screw to 1 1/2 Turns Out from Snug and Turn the Screw Out 1/4 Turn. Do the Over Rev Test. Continue this Process Until you have the Engine Over Revving without Struggle.
>>By Adjusting the Carburetor on this Style Carburetor Until the Engine Over Revs without Struggle, you have Adjusted the Air Mixture to the Best Possible Setting.
>>This file was Intended to Give you the Basic Carburetor Cleaning Instructions and May Not Reflect Your Carburetor Components.
>>If you have Questions, Please Ask. The links above Provide Good Directions on Cleaning the Carburetor. Make sure you use an Compressed Air to Blow through all the Carburetor Passages to make sure they are Clear.
>>1- http://www.repairfaq.org/samnew/lmfaq/lmclctc.htm
>>2- http://www.cpdonline.com/692509.pdf .
You can View a Breakdown/IPL of the Mower at this Site Addy, http://www.smallenginepartswarehouse.com/parts.asp and Select Shop Online Parts and Accessories. Now Select the Model Tab. Select the OEM (MTD) and Enter the Model Numbers. Now Double Click on the Model in the Results Area.
>>Have you Checked the Spark at the Plug?
>>Here is a Basic Instruction File I am in the Process of Making. It will Might Say Mower, but a Snow Thrower/Blower is Powered by the Same Type of Engine, so the Diagnostics are Basically the Same. >>***Here are some Diagnostic Instructions to Do on the Engine to Locate the Cause/Cure for a Hard/Not Starting Engine. This Does Not Include a Problem with the Valves. If I Suspected the Valves are Involved, then a Separate File for the Valves will be in this E-mail. This is a File in the Making, so Any Input is Appreciated.
>>1- Check the Spark. If Not Firing, then Replace the Plug.
>>2- If the Plug is Firing, then First, Pour a Small Amount of Gas (1oz) 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, then Make Sure the Gas is Free Flowing to the Carburetor. If the Gas is Free Flowing, 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.
>>3- If No Fire at the Plug, then Remove the Coil Shut Off Wire from the Kill Switch at the Engine Stop/Brake Bracket (where the End of the Stop/Brake Cable Attaches at the Engine). 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 is Bad. *On Some JD Model Mower the Engines Use an Igniter. Remove the Igniter and Coil and have your Local JD Dealer Test them for you.
>>* **On Models with Point Set, the Condenser is Bad and the Point Set and Condenser should be Replaced as a Unit. Make Sure the Point Set Plunger is Fully Extended when Setting the Point Set Gap to .020in.
>>** If there was No Response from the Engine When the Gas was Poured Into the Carburetor Throat and the Plug was Firing, then Check the Compression. If the Compression is Good, the Carburetor has Been Soaked and Cleaned and the Plug is Firing, then Check the Flywheel Key. If the Key is Damaged, then the Plug Firing is Incorrect to the Position of the Piston During the Compression (Power Stroke).
>>*** On the OHV and Some L-Head (Flat Head) Engines there is a Compression Release. The Exhaust Valve Clearance has to be Opened to .020in for the Compression Release Not to Operate; in Order to get a Correct Compression Reading.***
Please, Do Not Hesitate, If I Missed Something or 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. Be Safe and Be Happy. Thanks.

Good Luck

Respectfully

jbridger (John)

SOURCE: Yard-man model 12a-979L401 won't start (9 years old)

Hi,
My dad always taught me, rest his soul, that basic 101, if you have gas getting to spark, SOMETHING out to happen.
I'll ask a series of questions and propose some possible solutions. Hopefully we'll crack this mystery. Warning, this might be a tad lengthy... ha
1. Is the spark plug firing?
To check the coil that sends spark to your spark plug and the plug itself:
You can remove the spark plug from your engine and reconnect it to the spark plug wire while it just lays on your mower. pull the starter rope (make sure you're holding down the kill lever on the handle). Look at your plug end as you pull the rope.
Got spark? If yes, go to the next step, flagged ***. If no, look at the end of your spark plug that would go into the engine. The "L" shaped finger should be gapped from the small circular shape on the plug... this is the "gap". Your manual may provide specs on how wide this gap should be. If there is no gap, your plug won't work properly. The "L" shape is a soft metal and can be bent... create the proper gap. Try the test again to see if the plug is sparking. If not, you may have an issue with your coil.
***Yes to spark. Let's look at the gas issue now. OPTION 1. I will tell you that in my experience, water in gas is a major culprit for a mower not running. You've replaced all the filters... good.
I'm not sure of your mower, but most models have a "bowl" bolted to the bottom of the carburator. Sometimes moisture can get in the gas, get trapped in the bowl and won't go away or won't allow gas to get to the spark. Loosen the bolt... it's ok if gas from the bowl spills from this, the bowl doesn't hold much gas and it won't drain your tank. Plus, this means your carbuator is allowing the gas from the tank to the bowl. As you are looking at the gas spilled on the mower deck, see if there are beads of water in it. As you know, water and gas doesn't mix. This would be a tell tale of the problem. I would carefully remove the bowl from the carb and wipe it dry, then reassemble the bowl.
To be on the for sure side that you have no more water in your system, you could disconnect your fuel line from the gas tank and drain it out. Use a jar or container... you can see water in the bottom of it. You can reuse the gas too... just don't include the water!
OPTION 2. If your carb and tank are now H2O free and you're still getting to results, you may have a clogged jet on your carburator. This little pin-hole passage allows gas to pass through to the spark. Sometimes a mower sitting up a while, can cause a laquer effect to gas and it can block this passage. Removal of the carburator from the engine is required and a simple pin can be pushed through this passage to knock a "plug" out.
Geez I hope I didn't miss anything! ha
Good luck to you... I hope it's a quick and easy fix.

Curtis Sewell

• 7482 Answers
• Posted on Apr 16, 2011

SOURCE: My lawn push mower will

Check to make sure you are getting fire/spark at the plug, if so then do the following:
Check/Clean/Replace your fuel filter if you have one, normally they will be located in the fuel tank.
If the mower/weedeater is over a year old, then I recommend that you buy and install a new carburetor repair kit,because the diaphragm will get hard and that will cause it to be hard to crank.
Sounds like you will need to clean the carburetor or replace your carburetor internal rubber parts like the diaphgram and O rings.
Be sure to use compressed air to blow out all the fuel and air passages.
Be careful when blowing out the passages, because there are sometimes small rubber type seats in the bottom of some of the passages.
Sometimes you can get by with priming the carburetor or using starting fluid and letting it run a few times like that and it will flush the gunk out of the jets,but most of the time you will need to rebuild the carburetor.
Keep in mind that the float for the carburetor must be level when you go to reassemble the carburetor or follow the instrucitons you get with the carburetor kit.
When you clean your carburetor and remove the jet screws, you will first need to lightly seat the jet screws.
But before you lightly seat the jet screws count the number of turns it takes to seat the jet screws from their original position.
Be sure to mark the turns down on a piece of paper.
That way when you put the jets back in, you know to lightly seat them first and then turn them back out to their orginal position before you started.
This is a FREE answer,Please rate me

Roy Cagle

• 1545 Answers
• Posted on Jun 05, 2011

SOURCE: HI there, I got

There could well be a build up of sediment and debris in the main jet to the carburetor. It is easy to get to and clean. It is the brass bolt that holds the lower float bowl onto the main body of the carburetor. To clean it, drain your gas. Remove the bolt and external washer UNDER the carburetor bowl. Clean out the bowl of any sediment and/or water. To clean the brass bolt, use no metal objects. Carb/Choke aerosol spray cleaner will do the job. Pay close attention to the hole in the bottom of the bolt and the very small holes about 2/3 of the way up the bolt. Clean till shiny with holes cleared and reinstall. Your fuel flow problem and shut off condition may be solved.