Briggs and Stratton 31P977 Problems
| Engine Model: Briggs and Stratton 31P977 |
| Engine Type: 4-cycle 1-cylinder overhead valve air-cooled gasoline |
| Total Displacement: 30.6 cu.in (501 cc) |
| Rated Engine Power: 20 Hp (14.9 kW) at 3600 rpm |
| Fuel System Type: Float carburetor |
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| Engine starts hard or will not start |
Gas tank is empty - Add gasoline.
Improper fuel grade - Use quality gasoline.
Air trapped in fuel system - Bleed air.
Defective spark plug wire connection - Check spark plug wiring connection, repair or change.
Faulty spark plug - Change spark plug as required.
Fuel filter is clogged - Fuel filter needs changing.
Safety contact for brake pedal defective - Install new part.
Carburetor not adjusted - Adjust according to instructions.
Weak cylinder compression - Inspect cylinder block and change worn parts.
Throttle cable is damaged or adjusted incorrectly - Adjust properly or change the cable.
Air intake screen is plugged - Wash or clean as required.
Ignition system failure - Check ignition and replace faulty components.
Defective or stuck throttle cable - Clean or replace the cable.
Air filter is blocked - Clean or change air filter.
Dirty or faulty fuel pump - Test fuel pump and replace if necessary.
| Engine starts but then stalls |
Spark plug is defective - Spark plug need to be replaced.
Carburetor is dirty or faulty - Service or replace carburetor.
Faulty ignition coil - Ignition coil must be replaced.
Damaged or weak valve springs - Install new valve springs.
Stuck valves - Valves need to be cleaned.
Engine oil level is low - Checking oil level and add if necessary.
Excessive engine load - Reduce engine load.
Cooling fins are clogged - Wash or clean as required.
Carburetor mixture is too lean - Adjust carburetor correctly.
Ignition timing is improper - Set the ignition timing properly.
Incorrect valve setting - Set the valves correctly.
| Abnormal engine knocking or noise |
Low octane gasoline - Change gasoline.
Engine overloaded - Load reducing required.
Lack of engine oil - Add oil to the engine crankcase.
Incorrectly set low idle speed - Adjust the low idle speed.
Fuel pump is defective or dirty - Clean or install new fuel pump.
Crankshaft or main bearings are worn out - Install new parts as as required.
Valve clearance is improper - Adjustment procedure required.
Damaged piston rings or cylinder bore - Replace defective parts.
Improperly or clogged carburetor - Carburetor needs to be adjusted correctly or cleaned.
Air filter is dirty - Change or clean air filter.
Fuel pump is faulty or clogged - Check fuel pump and replace if necessary.
Defective ignition system - Inspect ignition system and change failed components.
Blown cylinder head gasket - Replace cylinder head gasket.
Stuck or burned valves - Change or service valves.
Push rod is damaged or worn - Install a new push rod.
Faulty cylinder block components - Change defective parts.
Oil filter is dirty (if equipped) - Change or clean oil filter.
| Excessive fuel consumption |
Throttle did not open fully - Replace or adjust throttle cable.
Improper adjustment of carburetor main jet - Adjust the carburetor main jet correctly.
Spark plug is loose or defective - Spark plug need to be tightened or replaced.
Burned, worn, or stuck valves - Replace or service valves.
Worn piston, rings, or sleeve - Replace defective parts.
Valve clearance is not correct - Adjust to proper valve clearance.
| Engine oil consumption is too high |
Gaskets or seals are excessively worn - New components need to be installed.
Worn valve stems and valve guides - Replace the valves.
Worn or stuck piston rings - Replace piston rings.
Cylinder liner or piston is worn - Check piston and liner, replace as required.
Breather hose or pipe is plugged - Clean or change.
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