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Welcome to the Lawnmower Man’s FREE Lawn Mower and Small Engine Repair Help

Free Troubleshooting tips that could help you repair your lawnmower or small engine today.

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“Disconnect your spark plug wire and ground it before doing any work.”

Please read your owner’s manual through and through before using and or doing any work on your equipment.

When lifting your lawnmower on its side, always lift from the carburetor or air filter side up so the oil and gas does not ruin the filter. Reasons to lift lawnmower include changing oil, sharpening or changing blade, or to clean under mower.

Safety while working or using a lawnmower

  1. Be sure to wear eye protection at all times while working on or using lawnmowers and small engines.
  2. Always wear full shoes when cutting grass.
  3. Never leave a running lawnmower unattended.
  4. I do not recommend cutting wet grass. The lawnmower engine will have to work twice as hard. The grass will also stop up your side discharge. The lawnmower should always be cut off before cleaning.

    Note: Never reach under the blade housing if the lawnmower is running. Not knowing how close the blade is to the side discharge, and you try to unplug the hole you could dismember your fingers or hand.

  5. Let your small engines cool off for at least 10min before refueling.
  6. Dispose of all harmful fluids at proper recycling plants.
  7. Keep all people and animals away from running lawnmowers.

Your Helpful troubleshooting tips Start NOW:

(Carburetion) (Section 1)

First check the air filter. Is it getting air and gas? If not lets find out why:

  1. Air Filters: There are 2 types. One is made of paper and the other is made of foam.

    Note: Whenever you lift your lawnmower for any reason disconnect your spark plug and ground it. Do not run your engine or any engine without the air filter, it will RUIN the motor.

    When lifting your lawnmower on its side, always lift it with the carburetor up. A little oil Will come out, but not enough to hurt anything. If you lift your lawnmower with the carburetor down oil & gas will go everywhere. If your air filter is made of paper the oil & gas will ruin it. If not you will have to clean your foam one.

    1. Paper filters cannot be cleaned with gas or any solvent, you can only use compressed air to blow the dirt out. If it’s very dirty, it’s best to replace.
    2. Foam filters can be cleaned with dish washing liquid and water and dried with a rag. Then very liberally, work new engine oil throughout the air filter and squeeze out excess. The oil in the filter is what traps the dirt. If your foam filter is deteriorating or coming apart replace it, it can ruin your engine. Clean every 25 hours under normal conditions.

      Note: Use the same type of engine oil you use in your small engine to lightly oil your filter.

  2. Check your gas cap. The gas cap is a source of ventilation for the fuel tank. If your gas cap is clogged it will make your fuel tank vapor lock, and you will have no gas flow. To check and see if the gas cap is bad, loosen the gas cap and see if it will run longer than before you loosened the gas cap. If it continues running, you need to replace the cap, if it does not continue running check further in this troubleshooting guide for more information.
  3. Is the fuel line clogged or partially clogged? Example: when you disconnect the fuel line from the carburetor and the gas is steadily flowing there is not a problem. But if it only drips with a full tank of gas replace it after checking the gas cap.
  4. Do you have a fuel cut off? If so, is it cut on?
  5. Do you have a gas filter? If so is it clear? If not, replace it.
  6. Is the gas flowing in to the carburetor? If not you could have a piece of trash in the needle & seat. The needle & seat controls the gas flow that starts & stops the gas. You will have to clean or replace. It’s best to replace.
  7. The float controls the gas level in the carburetor. If any of these signs occur, the carburetor is overflowing out of your air filter or out of your primer. If you have gas in your oil, you have carburetor problems.

    Note: Drain the oil if there is gas in it, if you don’t it can be dangerous.

    You need to check the needle & seat to see if it has trash or is bad. Is your float bad? To check the float pull the pin that holds your float in place, shake the float and if there is fluid inside of the float, replace it. Don’t forget to set the float level.

  8. Carburetors with primers represent a large majority of lawnmower and small engines today. They have primers to push or force air in the carburetor and in turn force gas through the center jet to make starting easier. Then look to see if the primer is pumping gas in to the engine.
  9. Things to check for if the primer is not working. This applies to several different types of engines. Check for holes or tears if you have a carburetor that has a diaphragm. (A diaphragm is a gas pump located in carburetors that have the gas tank and carburetors assembled together.) Replace the diaphragm if the diaphragm has a hole or has hardened or slightly slid over to one side, or if the engine will not run correctly and is skipping, not priming, or will not run at all. If you have a float type carburetor, the bowl gasket Will not be sealed properly and air will leak past the bowl gasket and will not prime. If you have a air assembly primer box where the air filter box is connected to carburetor, your gasket Will not be sealing correctly. If there is a tear or a hole in the gasket, air will leak past it and will not force air in the carburetor which will not force gas through the center jet. Also your air assembly box Will have a crack and will be warped because it was over tightened. If so, replace it.
  10. Some models have chokes. Chokes are used to draw gas through the center jet to run. If the choke is not working properly and it is not closing all the way the engine cannot draw gas through the center jet and will not crank.
  11. The throttle cable is what operates the choke on some models and the primer on some others, but it works the speed of the engine. To adjust the throttle that works the choke you need to loosen the throttle and open the throttle all the way, then push it until the choke is closed all the way. To adjust a “speed only” open the throttle all the way and make sure that the engine speed will be all the way open and then tighten the cable back up on the engine. Make sure if you have a kill switch on the throttle cable, that it works when you lower the speed all the way. If not, adjust again. Carburetors: Carburetors are the cause of 99% of all small engine problems. Carburetors are the easiest thing to repair on small engines.

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Section 2 Troubleshooting safety switch system

  1. Spark. There are several things that would keep a lawnmower or small engine from sparking like the safety switches. Lawnmowers and small engines have several different locations where the safety switches Will be. If your lawnmower or small engine doesn’t spark you need to get your owner’s manual and find out where your safety switches are and then try to trace the problem.
  2. Oil sensor. If you have one … The oil sensor will make your lawnmower or small engine quit running until you fill it with oil to the “full level.” This will cause the engine not to spark because of the oil being low. NOTE: This is a safety feature to protect your engine from running out of oil.
  3. Stop cable or blade brake. This cable is connected to the handle bar and you have to hold the handle bar down for your engine to run. This cable becomes stretched after some time and needs to be replaced. There is a safety switch on the other end of that cable, on the motor, that Will not be opening all the way and in turn, not letting the engine spark.
  4. Coils. Lawnmowers and small engines have changed a lot in the last 15 years. 99% of all lawnmowers and small engines today have electronic ignition coils which means no points. When you start your lawnmower or small engine and it runs until it gets hot and won’t start back again until it cools off you Will have a bad coil.
  5. Let your small engines cool off for at least 10min before refueling.
  6. Dispose of all harmful fluids at proper recycling plants.
  7. Keep all people and animals away from running lawnmowers.


The oil is the most important fluid in your lawnmower and small engine. Oil in small engines needs to be changed at least every 25hrs. The viscosity of oil wears out from the high heat the small engines put out. If you change your oil more often your small engine will last much, much longer. See your owners manual for the proper type of oil the engine needs and different climates use different grades of oil.

For example: Florida Will be 90 degrees mowers will use a thicker oil. In upstate New York where there is 35 degrees temperature, mowers & small engines will use a thinner oil for easier starting and lubrication.

Most all lawnmowers and small engines use the same type of oil. They have ratings to follow like API, SL, SJ, SH, SG, SD, MS etc….

Note: Most automotive oil’s will meet the type of oil that your small engine needs. Please consult your owner’s manual to be sure the type is correct. It’s best to change your oil when your small engine is warm.


  1. Blades. All blades basically are the same and most all blades will sharpen about the same. I have found that a 30 degree angle is best for lawnmower blades. NOTE: All blades must be level or balanced before putting them back on your mower, if they aren’t your lawnmower will vibrate. If your blade is bent, replace it. Do not try to straighten it. The blade must be the right blade for the lawnmower. DON’T, try to make a blade work if it is not right. If you have a blade on your mower that is not made for your lawnmower it could come off and seriously hurt, dismember, or kill someone. Do not take or add any washers unless whatever you are adding is made for the mower blade. The proper bolts for a blade are grade 8. Don’t try to use any other type of bolt. All blades must be torqued down to the specks that are in your owner’s manual.

The methods and techniques explained will apply to push mowers, riding mowers, tillers, go-karts, minibikes, generators, pressure washers, log splitters, shredders, edgers, walk behind blowers, and essentially all small single cylinder residential and commercial (one spark plug) engines 3hp-18hp etc….

Thank you for visiting my free troubleshooting page.

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