Mercury Force 90 Troubleshooting
| Engine Model: Mercury Force 90 |
| Engine Type: 2-stroke inline 3-cylinder gasoline outboard engine |
| Total Displacement: 71.1 cu.in (1.16 L) |
| Rated Engine Power: 90 Hp (67 kW) at 5500 rpm |
| Fuel System: Side-draft carburetor |
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| Engine doesn't start or starts hard |
Empty fuel tank - Add gasoline.
Low-quality gasoline - Change gasoline.
Air in fuel system - Bleed fuel system.
Faulty spark plug wire connection - Check spark plug wiring connection, repair or change.
Spark plug is damaged - Spark plug need to be replaced.
Fuel filter is plugged - Fuel filter needs to be replaced.
Carburetor problems - Carburetor diagnostics required.
Fuel lines are dirty - Service fuel lines.
Fuel tank air vent clogged or closed - Open or service air vent.
Low fuel pump pressure - Replace or rebuild fuel pump.
Worn or defective reed valve - Install new reed valve.
| Engine starts but stops suddenly |
Spark plug is damaged - Install new spark plug.
Dirty or defective carburetor - Service or change carburetor.
Faulty ignition coil - Ignition coil should be replaced.
Fuel tank air vent restricted or closed - Open or service air vent.
Fuel pump pressure is low - Replace or rebuild fuel pump.
Ignition system is defective - Check ignition system and replace faulty parts.
Fuel pump is faulty or clogged - Check fuel pump and replace if necessary.
Carburetor is not working properly - Inspect and adjust.
Dirty fuel lines - Clean fuel system lines.
Closed or clogged fuel tank air vent - Open or service air vent.
Plugged fuel filter - Fuel filter needs changing.
Gaskets are worn - Install new gaskets.
Engine is overloaded - Reduce engine load.
Too lean carburetor mixture - Use proper settings.
Incorrect ignition timing - Set the ignition timing correctly.
Thermostat failure - Replace thermostat.
Defective water pump - Water pump need to be replaced.
Propeller selection improperly - Replace propeller.
Propeller bent or damaged - Replace propeller.
Outboard motor is mounted too high or too low - Mount the motor as required.
| Abnormal engine noise or knocking |
Stale or low octane fuel - Use proper fuel.
Engine overload - Load reducing required.
Incorrectly adjusted low idle speed - Adjust idle speed.
Clogged or damaged fuel pump - Clean or install new fuel pump.
Worn main bearings or crankshaft - Replace crankshaft or bearings.
Piston rings or cylinder bore are damaged - Replace defective parts.
Improperly adjusted or dirty carburetor - Adjust carburetor properly or service it.
Clogged or defective fuel pump - Clean or change fuel pump.
Ignition failure - Check ignition and replace faulty components.
Gaskets are defective - Replace gaskets.
Powerhead components are faulty - Replace defective parts as required.
Propeller selection improperly - Install correct propeller.
Damaged or bent propeller - Replace propeller.
Motor mounted at incorrect height on transom - Adjust the outboard motor height correctly.
Incorrect trim angle - Adjust trim angle.
| Excessive fuel consumption |
Incorrect adjustment of carburetor main jet - Adjust it correctly.
Spark plug is defective or loose - Tighten or replace spark plug.
Piston, sleeve, or rings are damaged - Change faulty parts.
Propeller bent or damaged - Replace propeller.
Damaged propeller shaft - Replace propeller shaft.
Weeds wraped around propeller - Clean the propeller.
Engine mounting bolt is not tightened - Tighten bolt.
Damaged or loose steering pivot Tighten or replace.
Battery voltage is low - Battery is drained, charge it.
Battery runs out quickly - Service or replace the battery.
Disconnected battery cables or bad terminals - Check cable connections and change or clean terminals.
Defective starter motor - Repair or change starter.
| Trim motor runs but trim system does not move up or down |
Oil level is insufficient - Fill up oil.
Pump assembly is damaged - Check pump and replace if necessary.
Manual release valve leaking - Close the valve fully or replace it.
Motor or pump driveshaft faulty - Change defective component.
| Trim does not fully up or down |
Pump assembly faulty - Change pump.
Tilt ram piston ball is displaced - Service or repair.
Worn tilt ram piston O-ring - Replace O-ring.
Low oil level - Check oil level and add oil as required.
Lower check valve not seating in port side trim ram - Install valve correctly.
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| Outboard Engines Technical Specifications |
| Small Engines Technical Specifications |
| Car Engines Technical Specifications |
| Industrial Engines Technical Specifications |
