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How do I troubleshoot poor engine performance?


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 Many engine performance problems can be linked to maintenance issues such as stale fuel, dirty air filter, fouled spark plug, and deteriorated oil.

A great way to help avoid these problems would be to perform an annual tune-up using a Briggs & Stratton engine Maintenance Kit.


If this is the problem:

Ask this question:

If the answer is yes:

Engine runs poorly

Engine smokes

Is the engine emitting white/blue smoke?

Engine burning oil (see Engine emits white/blue smoke while running).

Is the engine emitting black smoke?

Adjust the carburetor (see Adjusting the Carburetor).

Is the air filter plugged?

Clean or replace the air cleaner (see Servicing Air Cleaners).

  

Engine overheats

Is the engine dirty?

Clean the engine (see Removing Debris).

Is the oil level low?

Add oil to the engine. NOTE: Never add oil to the gasoline for a four-stroke engine (see Checking & Changing Oil).

Are any shrouds or cooling fins missing or broken?

Install new parts as needed.

Is the fuel mixture too lean?

Adjust the carburetor (see Adjusting the Carburetor).

Is there a leaky gasket?

Replace the gasket (see Overhauling the Carburetor).

Is the fuel tank vent or fuel tank screen plugged?

Clean the fuel tank vent and fuel tank screen (see Removing and Cleaning the Fuel Tank).

Engine knocks

Does the combustion chamber contain excess carbon?

Clean carbon from the piston and head (see Removing Carbon Deposits).

Is the flywheel loose?

Inspect the flywheel and key; replace as needed (see Inspecting the Flywheel & Key).

Is the spark plug lead faulty?

Test the lead with a spark tester, then test the engine (see Servicing Spark Plugs).

  

Spark plug misses under load

Is the spark plug fouled?

Clean the spark plug (see Cleaning and Inspecting a Spark Plug).

Is the spark plug faulty or gap incorrect?

Replace the spark plug or adjust the spark plug gap (see Cleaning and Inspecting a Spark Plug).

Are the breaker points faulty?

Install a solid-state ignition (see Replacing the Ignition).

Is the carburetor set incorrectly?

Adjust the carburetor (see Adjusting the Carburetor).

Is the valve spring weak?

Replace the valve spring (see Servicing the Valves).

Is the valve clearance set incorrectly?

Adjust the valve clearance to recommended settings (see Servicing the Valves).
 


Other troubleshooting sections that may assist you can be found in either:


NOTE: Please read and abide by any applicable Safety Information (PDF) before performing any engine work. This information is not meant to take the place of work performed by a Briggs & Stratton Authorized Dealer. Terms and Conditions apply to all of our information provided on this website. Always be sure to read and understand your engine Operator's Manual. 
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