Briggs and Stratton 31Q777 Problems
| Engine Model: Briggs and Stratton 31Q777 |
| Engine Type: 4-cycle 1-cylinder overhead valve air-cooled gasoline |
| Total Displacement: 30.5 cu.in (500 cc) |
| Rated Engine Power: 18.5 Hp (13.7 kW) at 3300 rpm |
| Fuel System Type: Float carburetor |
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| Engine starts up hard or won't start |
Empty fuel tank - Fill it up.
Low-quality gasoline - Change gasoline.
Air or water in fuel system - Remove water or air from fuel system.
Spark plug wire is loose or disconnected - Inspect spark plug wiring connection, change or repair.
Spark plug is damaged - Change spark plug as required.
Fuel filter is dirty - Fuel filter needs to be replaced.
Faulty safety switch - Change damaged switch.
Carburetor is not adjusted - Check carburetor float adjustment.
Low compression - Check and replace worn parts.
Choke cable is unadjusted or damaged - Change cable or adjust correctly.
Cooling fins are blocked - Clean and wash as required.
Ignition system failure - Test ignition and replace failed parts.
Choke cable is stuck or faulty - Replace or clean the cable.
Dirty air filter element - Change or clean air filter.
Fuel pump is defective or dirty - Inspect fuel pump and change as required.
| Engine starts but immediately shuts off |
Damaged spark plug - Install new spark plug.
Carburetor is faulty or clogged - Carburetor needs to be replaced or cleaned.
Ignition coil is not working - Ignition coil should be replaced.
Bad or damaged valve springs - Install new valve springs.
Stuck valves - Valves must be cleaned.
Engine oil level is insufficient - Need to add engine oil.
Engine overloaded - Reduce engine load.
Plugged cooling fins - Wash or clean as required.
Carburetor is running lean - Set the carburetor properly.
Ignition timing is improper - Set the ignition timing correctly.
Valve setting is wrong - Valves needs to be set correctly.
| Abnormal engine noise or knocking |
Low octane gasoline - Use correct fuel.
Engine is overloaded - Reduce engine load.
Low engine oil level - Check and refill engine oil.
Low idle speed adjustment is incorrect - Adjust idling as required.
Dirty or faulty fuel pump - Inspect fuel pump and change as required.
Main bearings or crankshaft wear - Have bearings or crankshaft replaced.
Excessive valve clearance - Adjust valve clearance according to specifications.
Piston rings or cylinder bore are damaged - Replace faulty parts.
Clogged or improperly adjusted carburetor - Clean or properly adjust carburetor.
Dirty air filter element - Service or replace air filter.
Fuel pump is dirty or defective - Inspect fuel pump and change as required.
Defective ignition system - Inspect ignition system and change failed components.
Defective cylinder head gasket - Change cylinder head gasket.
Stuck or burned valves - Clean or change valves.
Push rod is worn or damaged - Push rod needs to be changed.
Damaged cylinder block parts - Replace defective parts.
Oil filter element is plugged (if equipped) - Service or change oil filter.
Insufficient choke opening - Inspect choke cable and adjust as required.
Incorrect carburetor main jet adjustment - Adjust it properly.
Spark plug is defective or loose - Re-tighten or replace spark plug.
Valves are worn, stuck, or burned - Change or service valves.
Worn rings, piston, or sleeve - Replace faulty components as required.
Valve clearance is incorrect - Check and adjust.
Damaged seals or gaskets - Replace worn parts to avoid leaks.
Valve stems and guides are worn - Need to replace the valves.
Piston rings are stuck or worn - Install new piston rings.
Worn piston or cylinder liner - Inspect liner and piston, change as necessary.
Blocked breather hose or pipe - Change or service.
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