Yamaha T8 Troubleshooting
| Engine Model: Yamaha T8 |
| Engine Type: 4-stroke 2-cylinder SOHC gasoline outboard engine |
| Total Displacement: 12 cu.in (197 cc) |
| Rated Engine Power: 8 Hp (5.9 kW) at 6000 rpm |
| Fuel System: Carburetor |
____________________________________________________________________________________
| Engine difficult to start or will not start |
Empty fuel tank - Fill fuel up.
Improper fuel grade - Use correct gasoline grade.
Water or air in fuel system - Remove air or water from system.
Damaged spark plug wiring connection - Inspect spark plug wiring connection, change or repair.
Spark plug is faulty - Replace spark plug.
Clogged fuel filter - Install new filter.
Problems with carburetor adjustment - Adjust as required.
Fuel lines clogging - Fuel lines must be clean.
Closed or restricted fuel tank air vent - Fuel tank air vent need to be opened or cleaned.
Fuel pump defective - Install new pump or repair it.
Choke cable is not adjusted properly or worn - Change cable or adjust correctly.
Excessive valve clearance - Adjust valve clearance.
Improper valve timing - Adjust valve timing correctly.
| Engine starts and stalls immediately |
Faulty spark plug - Change spark plug as required.
Dirty or defective carburetor - Clean or install new carburetor.
Damaged ignition coil - Replace ignition coil as necessary.
Fuel tank air vent restricted or closed - Open or service air vent.
Faulty fuel pump - Install new fuel pump or rebuild it.
Choke system is damaged - Check and repair choke system.
Valve clearance is wrong - Check and adjust.
Valve timing is improper - Adjust valve timing correctly.
Valve springs are bad or broken - Replace valve springs.
Stuck valves - Service the valves.
| Engine runs intermittently |
Defective ignition - Inspect ignition system and change failed components.
Fuel pump is defective or dirty - Service or change fuel pump.
Problems with carburetor adjustment - Adjust as required.
Restricted fuel lines - Fuel lines must be clean.
Fuel tank air vent restricted or closed - Fuel tank air vent need to be opened or cleaned.
Dirty fuel filter - Change fuel filter.
Gaskets are defective - Replace gaskets.
Water intake is blocked - Clean and wash as required.
Choke system malfunction - Check and repair choke system.
Engine overloaded - Reduce load.
Too lean fuel mixture in carburetor - Use proper settings.
Incorrect ignition timing - Ignition timing needs to be set properly.
Damaged thermostat - Install new thermostat.
Water pump is defective - Change water pump as required.
Propeller selection improperly - Install correct propeller.
Propeller bent or damaged - Replace propeller.
Outboard engine is positioned too low or too high - Position the engine correctly.
Engine oil level is low - Fill the crankcase with engine oil.
Faulty oil pump - Change oil pump.
Dirty water intake screen - Clean and wash as required.
Improper valve setting - Adjust valves as required.
| Engine knocking sound or abnormal noise |
Low octane fuel - Use proper gasoline.
Excessive engine load - Load reducing required.
Too low idle RPM - Correct idle settings.
Fuel pump is defective or dirty - Clean or change fuel pump.
Worn main bearings or crankshaft - Repair or replace defective parts.
Damaged cylinder bore or piston rings - Change faulty parts.
Carburetor is dirty or incorrectly adjusted - Clean or properly adjust carburetor.
Fuel pump is faulty or clogged - Service or replace fuel pump.
Ignition failure - Inspect ignition system and change failed components.
Cylinder head gasket is blown - Install new cylinder head gasket.
Powerhead parts are worn out - Defective components need to be replaced.
Valves are stuck or burned - Clean or change valves.
Propeller selection improperly - Check the propeller size.
Propeller bent or damaged - Have propeller repaired or replaced.
Outboard motor mounting height is set incorrectly - Have motor adjusted to proper transom height.
Incorrect trim angle - Make the correct trim angle adjustment.
| Engine using too much gasoline |
Carburetor main jet adjustment is improper - Adjust it correctly.
Spark plug is defective or loose - Spark plug need to be tightened or replaced.
Sleeve, piston, or rings are damaged - Replace faulty components.
| Excessive motor vibration |
Damaged or improper size of propeller - Have propeller repaired or replaced.
Propeller shaft malfunction - Have propeller shaft replaced.
Weeds clogs the propeller - Remove weeds from propeller.
Engine mounting bolt is not tightened - Tighten bolt.
Steering pivot is loose or damaged Tighten correctly or replace.
Low battery output - Recharge the battery.
Battery drains quickly - Service battery or replace it.
Faulty battery terminals or disconnected cables - Check wiring and clean or replace terminals.
Damaged starter motor - Starter should be replaced.
| Trim motor runs but trim system does not move up or down |
Low oil level - Checking oil level and add if necessary.
Damaged pump assembly - Inspect pump and change as required.
Manual shut-off valve leaks - Valve need to be closed or changed.
Motor or pump driveshaft faulty - Change worn component.
| Trim does not fully up or down |
Damaged pump assembly - Change pump.
Tilt ram piston ball is displaced - Clean or repair.
Tilt ram piston O-ring damaged - Install new O-ring.
Insufficient oil - Checking oil level and add if necessary.
Lower check valve is not properly secured in port side trim ram - Install valve correctly.
____________________________________________________________________________________
| Outboard Engines Technical Specifications |
| Small Engines Technical Specifications |
| Car Engines Technical Specifications |
| Industrial Engines Technical Specifications |
