________________________________________________________________________________________
| Home / Outboard Engines / Mercury Engines / Mercury 15 Hp |
Mercury 15 Hp Troubleshooting
| Engine will not start or starts up hard |
Empty fuel tank - Add fuel.
Low-quality gasoline - Change fuel.
Clogged fuel system - Remove clogging.
Faulty spark plug wire connection - Inspect the spark plug wire connection, replace or repair.
Defective spark plug - Spark plug need to be replaced.
Dirty fuel filter - Change fuel filter.
Incorrect carburetor adjustment - Adjust carburetor idle mixture screw.
Dirty fuel lines - Service fuel lines.
Fuel tank air vent restricted or closed - Open or service air vent.
Fuel pump pressure is low - Change or rebuild fuel pump.
| Engine starts and immediately shuts off |
Defective spark plug - Spark plug need to be replaced.
Carburetor is clogged or faulty - Replace or service carburetor.
Faulty ignition coil - Ignition coil should be replaced.
Fuel tank air vent restricted or closed - Open or service air vent.
Low fuel pump pressure - Install new fuel pump or rebuild it.
Thermal relief valve not functioning - Install new relief valve.
| Unstable engine running |
Ignition system is defective - Check ignition and replace faulty components.
Dirty or faulty fuel pump - Clean or install new fuel pump.
Carburetor settings incorrect - Adjusting as required.
Fuel lines clogging - Fuel lines need to be cleaned.
Closed or clogged fuel tank air vent - Open or service air vent.
Fuel filter is clogged - Change fuel filter.
Worn gaskets - Install new gaskets.
| Engine keeps overheating |
Engine is under excessive load - Reduce engine load.
Carburetor is running lean - Set the carburetor correctly.
Wrong ignition timing - Set the ignition timing correctly.
Faulty thermostat - Install new thermostat.
Damaged water pump - Change water pump as required.
| Abnormal engine knocking or noise |
Stale fuel - Use proper gasoline.
Excessive engine load - Reduce load.
Low idle speed setting is not correct - Correct the settings.
Fuel pump is faulty or clogged - Clean or install new fuel pump.
Crankshaft or main bearings wear - Need to install new components.
Damaged cylinder bore or piston rings - Change faulty parts.
| Engine power is insufficient |
Improperly adjusted or dirty carburetor - Adjust the carburetor correctly or clean it.
Clogged or damaged fuel pump - Service or replace fuel pump.
Defective ignition - Check ignition system and replace faulty parts.
Gaskets are damaged - Replace gaskets.
Worn powerhead components - Replace defective parts.
| Excessive fuel consumption |
Improper adjustment of carburetor main jet - Adjust main jet as required.
Loose or faulty spark plug - Re-tighten or replace spark plug.
Worn sleeve, rings, or piston - Replace faulty components.
| Trim motor is running but system can't move |
Insufficient oil - Check oil level and add oil as required.
Defective pump assembly - Inspect pump and change as required.
Leakage of manual drain valve - Valve need to be closed or changed.
Broken motor or pump driveshaft - Replace worn component.
| Trim cannot be fully up or down |
Pump assembly is faulty - Change pump as required.
Tilt ram piston ball is displaced - Clean or repair.
Worn tilt ram piston O-ring - Replace O-ring.
Oil level is low - Check oil level and add oil as required.
Lower check valve not seating in port side trim ram - Secure valve properly.
________________________________________________________________________________________
________________________________________________________________________________________
| Engines Technical Specifications |