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Briggs and Stratton 28Q777 Problems
The Briggs and Stratton 28Q777 is a 465 cc (28.38 cubic inches) single-cylinder air-cooled 4-cycle internal combustion gasoline engine, manufactured by Briggs and Stratton.
The Briggs 28Q777 engine has an OHV (overhead valve) design and a vertical PTO shaft. This engine is equipped with float type carburetor and an electronic ignition system. The engine used a paper air filter with a foam pre-cleaner.
The cylinder bore is 87.30 mm (3.44 in) and the piston stroke is 77.7 mm (3.06 in). This engine output 15.6 PS (11.5 kW; 15.5 HP) at 3,300 rpm of maximum power.
Engine code identification:
28 - Total displacement,
Q - Basic design series,
7 - Vertical PTO-shaft,
7 - Plain bearing pressure lubrication,
7 - Electric starter.
| Engine starts hard or will not start |
No gasoline in tank - Fill it up.
Wrong grade of gasoline - Use quality fuel.
Air in the fuel system - Air bleeding.
Defective spark plug wire connection - Inspect spark plug wiring connection, change or repair.
Damaged spark plug - Change spark plug as required.
Dirty fuel filter - Install new filter.
Brake pedal not pushed down - Push the brake pedal down.
Carburetor problems - Carburetor diagnostics required.
Bad engine compression - Inspect cylinder block and replace worn components.
Choke cable is not adjusted properly or worn - Change cable or adjust correctly.
| Unstable engine running |
Plugged cooling fins - Clean and wash as required.
Defective ignition - Check ignition and replace faulty components.
Defective or stuck throttle cable - Change or service the cable.
Clogged air filter - Change or service air filter.
Clogged or damaged fuel pump - Test fuel pump and replace if necessary.
| Engine starts but then shuts off |
Damaged spark plug - Change spark plug as required.
Faulty or clogged carburetor - Clean or install new carburetor.
Ignition coil is faulty - Ignition coil must be replaced.
Worn or loose valve springs - Install new valve springs.
Stuck valves - Valves must be cleaned.
| Engine is overheated |
Engine oil insufficient - Fill up the engine oil.
Engine overload - Reduce load.
Cooling fins are blocked - Clean and wash as required.
Carburetor mixture is too lean - Set the carburetor properly.
Ignition timing is incorrect - Adjust ignition timing as required.
Valve setting is incorrect - Set the valves properly.
| Engine knocking or noise |
Stale gasoline - Use correct fuel.
Excessive engine load - Reduce load.
Insufficient engine oil - Check and refill engine oil.
Incorrect low idle setting - Correct idle adjustment.
Clogged or damaged fuel pump - Service or change fuel pump.
Worn crankshaft or main bearings - Need to install new components.
Incorrect valve clearance - Adjust to proper valve clearance.
Worn cylinder bore or piston rings - Change defective components.
| Engine lacks power |
Incorrectly adjusted or clogged carburetor - Adjust carburetor properly or service it.
Clogged air filter - Change or clean air filter.
Fuel pump is faulty or clogged - Service or change fuel pump.
Ignition system malfunction - Check ignition and replace faulty components.
Damaged cylinder-head gasket - Replace the gasket as required.
Stuck or burned valves - Replace or service valves.
Push rod is worn or damaged - Change push rod.
Worn cylinder block parts - Replace defective components as required.
Oil filter is dirty (if equipped) - Replace or clean oil filter.
| Engine uses too much fuel |
Throttle not fully open - Check throttle cable and adjust as required.
Carburetor main jet adjustment is improper - Adjust it correctly.
Loose or defective spark plug - Spark plug need to be tightened or replaced.
Stuck, burned, or worn valves - Clean or replace valves.
Worn piston, rings, or sleeve - Change defective components.
Incorrect valve clearance - Adjust to proper valve clearance.
| Excessive engine oil consumption |
Gaskets or seals can be faulty - Replace to repair leaks.
Worn valve stems and valve guides - Replace defective valves.
Piston rings are stuck or worn - Have piston rings replaced.
Damaged piston or cylinder liner - Inspect liner and piston, fit new parts as necessary.
Breather pipe or hose is clogged - Service or replace.
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