Mercury 350 L6 Verado Problems
| Engine Model: Mercury Verado 350 L6 |
| Engine Type: 4-stroke inline 6-cylinder supercharged gasoline outboard engine |
| Total Displacement: 158.5 cu.in (2.6 L) |
| Rated Engine Power: 350 Hp (257 kW) at 6400 rpm |
| Fuel System: Sequential multi-point electronic fuel injection (EFI) |
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| Engine will not start or difficult to start |
No gasoline in tank - Fill gasoline up.
Low-quality gasoline - Use quality fuel.
Dirt and debris in fuel system - Remove debris and dirt.
Damaged spark plug wiring connection - Check spark plug wiring connection, repair or change.
Damaged spark plug - Spark plug need to be replaced.
Fuel filter is dirty - Fuel filter needs to be replaced.
Vapor separator needle valve is bend or wear - Change vapor separator needle valve.
Dirty fuel lines - Clean fuel system lines.
Fuel tank air vent clogged or closed - Open or service air vent.
Fuel feed pump defective - Replace or rebuild fuel feed pump.
Worn or improperly adjusted choke cable - Adjust correctly or replace the cable.
Incorrect valve clearance - Adjustment procedure required.
Valve timing is incorrect - Set the valve timing correctly.
Fuel pressure is low - Inspect fuel system for leaks or inspect low pressure fuel pump.
Fuel injector is clogged or malfunction - Replace or clean as required.
Fuel regulator is defective - Replace fuel regulator.
ECM is faulty - Change electronic control modul.
| Engine starts but stalls immediately |
Faulty spark plug - Spark plug need to be replaced.
Vapor separator needle valve is worn or defective - Change vapor separator needle valve.
Ignition coil is not working - Replace ignition coil as necessary.
Fuel tank air vent restricted or closed - Fuel tank air vent need to be opened or cleaned.
Fuel pump is faulty - Repair or change fuel pump.
Choke system is damaged - Inspect and replace choke system components.
Valve clearance is wrong - Adjust valve clearance.
Wrong valve timing - Adjust valve timing correctly.
Broken or loose valve springs - Change valve springs.
Valves sticking - Valves must be cleaned.
Bad compression - Inspect and replace defective parts.
Plugged fuel filter - Fuel filter needs to be replaced.
Fuel injector is faulty or clogged - Clean or install new injector.
Insufficient engine oil - Fill the crankcase with engine oil.
Oil pump is defective - Replace oil pump.
Water intake is clogged - Need to wash or clean.
Defective thermostat - Install new thermostat.
Defective water pump - Install new water pump.
| Engine runs intermittently |
Ignition system malfunction - Inspect ignition system and change failed components.
Dirty or defective fuel pump - Service or replace fuel pump.
Vapor separator needle valve is bend or wear - Replace needle valve.
Restricted fuel lines - Clean fuel system lines.
Fuel tank air vent clogged or closed - Open or service air vent.
Plugged fuel filter - Change fuel filter.
Intake manifold is air leaking - Install new gasket.
Water intake screen is dirty - Need to wash or clean.
Throttle valve and throttle link are defective or worn - Replace faulty parts.
Fuel injector is faulty or clogged - Replace or clean if necessary.
Engine is overloaded - Load reducing is recommended.
Fuel injector or fuel pump is clogged - Replace or clean as required.
Bad ignition timing - Adjust ignition timing correctly.
Damaged thermostat - Replace thermostat.
Water pump failure - Water pump need to be replaced.
Incorrect propeller selection - Install correct propeller.
Damaged or bent propeller - Replace propeller.
Outboard motor is positioned too low or too high - Mount the motor as required.
Engine oil level is low - Fill up the engine oil.
Defective oil pump - Replace oil pump.
Water intake is blocked - Wash or clean as required.
Valve setting is improper - Adjust valves correctly.
Stale gasoline - Use correct gasoline.
Excessive engine load - Load reducing required.
Low idle speed setting is incorrect - Adjust as required.
Dirty or damaged fuel pump - Test fuel pump and change if necessary.
Main bearings or crankshaft wear - Worn parts replacement required.
Piston rings or cylinder bore are worn - Change faulty parts.
Dirty fuel lines - Fuel lines need to be cleaned.
Defective fuel injector - Inspect fuel injector and change as required.
Fuel pump is dirty or defective - Service or change fuel pump.
Ignition system problems - Check ignition system and replace faulty parts.
Cylinder head gasket is blown - Change cylinder head gasket.
Faulty powerhead parts - Defective components need to be replaced.
Stuck or burned valves - Clean or change valves.
Incorrect propeller selection - Replace propeller.
Damaged or improper size of propeller - Replace propeller.
Outboard engine mounting height improperly - Have motor adjusted to proper transom height.
Incorrect trim angle - Adjust trim angle.
| Engine uses too much fuel |
Dirty or faulty fuel injector - Replace or clean as required.
Defective or loose spark plug - Spark plug need to be tightened or replaced.
Worn piston, rings, or sleeve - Change faulty parts.
ECU is not functioning - Install new ECU.
| Engine vibrates excessively |
Propeller bent or damaged - Have propeller repaired or replaced.
Damaged propeller shaft - Propeller shaft needs to be replaced.
Weeds clogs the propeller - Remove and clean propeller.
Engine mounting bolt is not tightened - Tighten the bolt as required.
Damaged or loose steering pivot Tighten correctly or replace.
Low battery output - Low battery charging, charge as required.
Battery drains quickly - Service battery or change it.
Bad terminals or disconnected battery cables - Check cables and clean or change terminals.
Faulty starter motor - Repair or install a new starter.
| Trim motor runs but trim system does not move up or down |
Insufficient oil - Checking oil level and add if necessary.
Pump assembly is damaged - Check pump and change if required.
Manual release valve leaking - Close the valve or change it.
Faulty pump driveshaft or motor - Change worn component.
| Trim does not fully up or down |
Pump assembly is faulty - Replace pump.
Tilt ram piston ball is in wrong position - Service or repair.
Tilt ram piston O-ring is worn - Change O-ring.
Oil level is insufficient - Need to add the oil.
Lower check valve not seating in port side trim ram - Install valve correctly.
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