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Briggs and Stratton 31Q777 Problems
| Engine Model: Briggs and Stratton 31Q777 |
| Engine Type: 4-cycle single cylinder OHV vertical shaft gasoline engine |
| Total Displacement: 30.5 cu.in (500 cc) |
| Rated Engine Power: 18.5 Hp (13.7 kW) at 3600 rpm |
| Fuel System: Float type carburetor with fixed main jet |
| Engine will not start or difficult to start |
Empty fuel tank - Add gasoline.
Improper fuel grade - Use quality fuel.
There is air in the fuel system - Bleed the system.
Disconnected or loose spark plug wire - Inspect the spark plug wire connection, replace or repair.
Spark plug is faulty - Spark plug need to be replaced.
Fuel filter is plugged - Install new filter.
Defective safety switch - Replace if required.
Carburetor is dirty - Wash, clean and adjust.
Low cylinder compression - Check cylinder block and replace worn parts.
Throttle cable is adjusted improperly or worn - Adjust correctly or replace the cable.
| Engine runs intermittently |
Air intake screen is blocked - Clean and wash as required.
Defective ignition - Check ignition system and replace faulty parts.
Choke cable is defective or stuck - Change or service the cable.
Dirty air filter element - Clean or replace air filter.
Fuel pump is faulty or clogged - Test fuel pump and change if necessary.
| Engine starts and stops immediately |
Spark plug is damaged - Spark plug need to be replaced.
Faulty or dirty carburetor - Clean or install new carburetor.
Faulty ignition coil - Change ignition coil as required.
Bad or broken valve springs - Change valve springs.
Stuck valves - Valves need to be cleaned.
Engine oil level low - Add oil to the engine crankcase.
Engine overload - Load reducing required.
Cooling fins are plugged - Clean and wash as required.
Carburetor is running lean - Set the carburetor properly.
Ignition timing is incorrect - Set the ignition timing properly.
Improper valve setting - Set the valves properly.
Stale gasoline - Use proper gasoline.
Engine is overloaded - Reduce load.
Not enough engine oil - Need to add engine oil.
Low idle speed adjustment is incorrect - Test and adjust.
Clogged or defective fuel pump - Check fuel pump and change if required.
Main bearings or crankshaft wear - Have bearings or crankshaft replaced.
Excessive valve clearance - Check and adjust.
Worn piston rings or cylinder bore - Replace faulty components.
| Engine power is insufficient |
Carburetor is clogged or improperly adjusted - Clean or correctly adjust carburetor.
Air filter element is plugged - Replace or service air filter.
Dirty or damaged fuel pump - Clean or install new fuel pump.
Ignition system is defective - Check ignition system and replace faulty parts.
Worn cylinder head gasket - Replace the gasket as required.
Valves are burned or stuck - Clean or change valves.
Push rod is bent or worn - Install a new push rod.
Damaged cylinder block parts - Replace defective components as required.
Plugged oil filter (if equipped) - Replace or service oil filter.
| Engine using too much gasoline |
Choke doesn't open well - Adjust or replace choke cable.
Improper adjustment of carburetor main jet - Adjust main jet as required.
Spark plug is defective or loose - Spark plug need to be replaced or tightened.
Worn, stuck, or burned valves - Service or replace valves.
Worn sleeve, piston, or rings - Replace defective components.
Excessive valve clearance - Check and adjust.
| Excessive engine oil consumption |
Worn seals or gaskets - Replace worn parts to avoid leaks.
Valve stems or guides are damaged - Replace defective valves.
Piston rings are defective or worn - Piston rings need to be replaced.
Piston or cylinder liner is scored - Check piston and liner, change as required.
Blocked breather hose or pipe - Service or replace.
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