Benefits of Regular Service:
Servicing your small engine on a regular basis offers many advantages over the Wait-Until-It-Breaks Maintenance Program.
  • By establishing a service schedule, you will gain confidence that whenever you need the unit it will be ready for use.
  • By performing a number of service functions together, you will save time. You can pick up all needed parts and lubricants in one trip to the parts store. Then you need to disassemble a component only once to perform numerous service procedures rather than taking it apart many times.
  • Regular service gives you a chance to visually inspect the entire engine and related components for damage, wear, and other potential problems.

How, Where, and When to Service:
Knowing how to service is as important as knowing when. Some service procedures can be performed wherever you store your boat: in a garage, storage shed, or tool shed. If the unit is heavy, you can build a ramp up to a sturdy table that is at a handy height for working. Or you can use a ratchet winch to lift the engine. Units weighing less than 40 pounds may be lifted to a workbench or table as long as you lift with your legs rather than with your back. Get help if you need it, and make sure that the unit will remain sturdily in place as you service it. Remember to always put safety first.
Servicing a small engine is easy once you know what to do and when to do it. A service chart can help you determine common service requirements as well as track what service has been done. Your unit may have a service chart in the owner's manual or service manual. Typical recommendations include changing engine oil and tuning up the engine at least once a year.The purpose of ongoing service, also known as Preventive Maintenance, is to keep your engine in good operating condition. Ongoing service procedures include air cleaner service, crankcase breather service, cooling system service, muffler service, tune-up, and lubrication service.
- Lubrication service means making sure that all moving parts have sufficient lubrication (oil and/or grease) to minimize wear. Lubrication service procedures include mixing oil with fuel in two-stroke engines, and lubricating other moving parts.
- A tune-up consists of the adjustment and/or replacement of parts critical to smooth and efficient engine operation. Those parts include components in all engine systems: fuel, exhaust, ignition, combustion, cooling, and lubrication. Ignition tune-ups are more important for mechanical-breaker ignitions than they are for self-contained solid-state ignitions. Regular tune-ups will keep your small engine running smoothly and reduce the need for repairs.

What can you do about this lack of information?
Fortunately, there are numerous after-market publishers of service manuals for specific models of small engines. If you don't have an owner's manual, you can contact the manufacturer directly to purchase one; manufacturers also sell service manuals. Most manufacturers keep product manuals for up to 20 years.

How to Repair a Small-Engine Fuel System:
The function of a small engine fuel system is to store and deliver fuel to the combustion chamber. Maintaining a fuel system includes servicing the fuel filter, air cleaner, fuel tank, fuel lines, and adjusting the carburetor. Of course, not all small engines have all of these components. Some small engines have a fuel strainer in the bottom of the fuel tank. Others have a removable fuel strainer in the fuel line. Still, other small engines use disposable in-line fuel filters made of pleated paper.

To clean sediment from a tank:
1: Drain or siphon all fuel from the tank.
2: With a flashlight, find the lowest point in the tank: the sediment reservoir. Clean all sediment from the reservoir indentation.
3: Wipe sediment from the end of the filter element.
4: Wipe the inside of the tank with a clean rag.
5: Refill the fuel tank.

Here is how to clean sediment from a fuel strainer:
1: Find and close the shutoff valve on the fuel line.
2: Loosen the lock nut on the bowl retainer and remove the sediment bowl.
3: Empty and clean the sediment bowl. Clean the filter screen. Refill the sediment bowl with fresh fuel.
4: Reinstall the sediment bowl and bowl retainer, tightening the lock nut.
5: Open the shutoff valve.

Here is how to replace an in-line fuel filter:
1: Find and close the shutoff valve on the fuel line or use a clothespin to pinch the fuel line closed.
2: Disconnect the fuel filter from the fuel line.
3: Replace the in-line fuel filter with an exact replacement part.
4: Open the shutoff valve.

Servicing Air Cleaners:
The purpose of an air cleaner on a small engine is to keep large particles in the air from clogging the carburetor. The two types of air cleaners used on small engines are oil bath and dry.

1: Remove the cover of the air cleaner, typically by unscrewing a nut on top of the cleaner.
2: If it's an oil cleaner, remove all oil and contaminants from the center channel of the cleaner, wipe it clean, then replace oil to the indicated level. A dry cleaner cannot be cleaned and therefore must be replaced.
3: Replace the air cleaner cover and make sure all fasteners are securely tightened.
Servicing Fuel Tanks and Lines

Fuel systems with pumps use non pressurized fuel tanks. Outboard engines typically use pressurized tanks. Fuel lines are usually made of neoprene.

1: Remove the cap from the fuel tank.
2: Using a flashlight, check for sediment in the fuel tank. If sediment is found, clean the tank and replace the fuel. Replace the fuel cap when done.
3: Check the fuel line and siphon bulb, if there is one, by squeezing them and inspecting for cracks. If damaged, replace with a line or a bulb of the same inside diameter. Make sure it is approved for use with fuel.

Adjusting Carburetors:

A carburetor mixes fuel and air in the correct proportion for use by the engine. The three types of carburetors commonly used in small engines are natural draft, updraft, and downdraft. These names describe the direction that air flows from the inlet to the engine manifold. To maintain your small engine, you will want to make sure the carburetor's speed and mixture are correctly adjusted. Here's how to adjust the typical three-adjustment carburetor:

1: With the engine running, open the throttle wide. Turn the high-speed adjustment needle forward and backward until the highest speed setting is found.
2: Move the throttle to the slowest running speed. Adjust the idle-speed needle until the recommended idle speed is found.
3: Once the idle speed has been set, adjust the idle mixture until the engine runs smoothly.

Spark Plugs:
The spark plug in a small engine must withstand high voltage, high heat, and millions of ignitions during its life. A new spark plug requires about 5,000 volts of electricity to jump the gap. A used spark plug may require twice as much voltage to function. So servicing the spark plug is important to your engine's operation.

1: Disconnect the lead wire from the top of the spark plug.
2: Using the appropriate spark plug wrench, loosen the plug from the cylinder head. Before removing the plug, clean debris from around the spark plug base.
3: Note the electrode's appearance. Excessive buildup can mean incorrect fuel-air mixture, incorrect carburetor adjustment, weak spark voltage, or poor air cleaner maintenance, among other causes.
4: Clean the spark plug surface with a soft cloth and the electrode with a wire brush or spark plug cleaning unit. If the electrode is worn or damaged, replace the spark plug with one of the same size and heat range to avoid any damage to the engine.
5: Using a feeler gauge, set the gap on the spark plug electrode to the manufacturer's recommendations.

Lubrication Service:
Lubrication service is the application of lubricating greases. Greases are simply petroleum products with higher viscosity or thickness than oils. A lubricating grease may have a grade as low as 60 (about twice as thick as 30 grade oil) to over 100. Common viscosities for lubricating greases are 80 and 90 grade. At these viscosities, lubricants have the density of toothpaste. Special tools called lube guns are used to apply lubricating greases. Professional repair shops use pressurized lube guns; the engine owner can apply lubricating greases with a ratchet lube gun. The greases are sold in tubes that fit into the lube gun.

1: Check the owner's manual for specific information on lubrication: where and with what.
2: Apply the recommended grade of lubricating grease. Some components have fittings to which the end of the lube gun is attached. Others require that the top of a reservoir is opened and fluid added to a specific FULL point. Still other components require that a lubricant such as white grease be spread on the part by hand.

CAUTION: Make sure that lubricating greases do not touch electrical parts. Lubricants can conduct electricity, shorting out the system and potentially causing a fire.