Mercury 350 MAG MPI - User Manual

Other manuals for Mercury 350 MAG MPI

Installation Manual77 pages

Questions and Answers

B
biancamoodyAug 16, 2025
What to do if Mercury 350 MAG MPI Engine will not start or is hard to start?
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  shannon97Aug 16, 2025
  If your Mercury Engine won't start or is hard to start, consider these potential causes: * Improper starting procedure: Refer to the starting procedure. * Empty fuel tank or closed fuel shutoff valve: Refill the tank or open the valve. * Choke not operating correctly (Carburetor Models): Inspect choke linkages for free movement. * Engine flooded: Wait at least 5 minutes before attempting to restart. Refer to Starting Procedures. * Faulty ignition system component: Service the ignition system. * Clogged fuel filters: Replace the filters. * Stale or contaminated fuel: Drain the tank and refill with fresh fuel if contaminated. * Fuel line or tank vent line kinked or clogged: Replace any kinked lines or use compressed air to clear obstructions.
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xmitchellAug 19, 2025
What to do if Mercury 350 MAG MPI Engine starter motor will not crank engine, or cranks slow?
- S
  Sherry BrownAug 19, 2025
  If the starter motor on your Mercury Engine won't crank the engine or cranks slowly, check the following: * Ensure the battery switch is turned on. * Make sure the remote control is in the neutral position. * Check and reset any open circuit breakers, or replace blown fuses. * Inspect all electrical connections and wires (especially battery cables) for looseness, dirt, or damage. Clean and tighten any faulty connections. * Test the battery and replace it if it's bad.
K
Kendra FisherAug 22, 2025
Why Mercury 350 MAG MPI runs rough, misses and/or backfires?
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  Anthony WilliamsAug 22, 2025
  If your Mercury Engine runs rough, misses, or backfires, here are a few things to check: * Idle speed too low (EFI Models): Have the EFI system checked by an Authorized MerCruiser Dealer. * Choke not operating properly (Carburetor Models): Check choke linkages for binding or obstruction. * Ignition System Fault: Service the ignition system. * Clogged fuel filter: Replace the filter. * Stale or contaminated fuel: If contaminated, drain the tank and fill with fresh fuel. * Kinked or clogged fuel line or fuel tank vent line: Replace kinked lines or blow out lines with compressed air to remove any obstruction. * Flame Arrestor plugged with foreign material: Clean the Flame Arrestor.
T
Theresa FosterAug 28, 2025
What causes poor performance in a Mercury 350 MAG MPI Engine?
- R
  roberto88Aug 28, 2025
  Poor performance in your Mercury Engine can stem from several factors: * Throttle not fully open: Inspect the throttle cable and linkages for proper operation. * Damaged or improper propeller: Replace the propeller. * Excessive bilge water: Drain and check for the cause of entry. * Boat overloaded or load improperly distributed: Reduce the load or redistribute it more evenly. * Boat bottom fouled or damaged: Clean or repair as necessary. * Flame Arrestor dirty: Clean the Flame Arrestor.
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greggdavisAug 31, 2025
What to do if Mercury 350 MAG MPI Engine battery will not come up on charge?
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  Wyatt ThomasAug 31, 2025
  If the battery on your Mercury Engine won't come up on a charge, consider these possibilities: * Excessive current draw from the battery: Turn off any non-essential accessories. * Loose or dirty electrical connections or damaged wiring: Check all associated electrical connections and wires (especially battery cables). Clean and tighten faulty connections. Repair or replace any damaged wiring. * Alternator drive belt loose or in poor condition: Replace and/or adjust the belt. * Unacceptable battery condition: Test the battery.
D
David LawrenceSep 3, 2025
What causes excessive transmission fluid temperature or slipping transmission in Mercury 350 MAG MPI?
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  Donna WarnerSep 3, 2025
  If you're experiencing excessive transmission fluid temperature or a slipping transmission in your Mercury Engine, check these potential causes: * Low fluid level: Maintain the correct fluid level. * Transmission shift lever not positioned properly: Inspect the shift linkages and shift lever positioning. * Fluid cooler hoses kinked: Straighten the hoses or replace them if damaged.
J
jenniferburnsSep 6, 2025
Why Mercury 350 MAG MPI Engine remote control operates hard, binds, has excessive free-play or makes unusual sounds?
- R
  rodriguezjuanSep 6, 2025
  If the remote control for your Mercury Engine operates hard, binds, has excessive free-play, or makes unusual sounds, consider the following: * Insufficient lubrication on shift and throttle linkage fasteners: Lubricate them. * Obstruction in shift or throttle linkages: Remove any obstruction. * Shift or throttle cable kinked: Straighten the cable or have a dealer replace it if damaged beyond repair.
C
Carla JeffersonSep 9, 2025
What causes low engine oil pressure in Mercury 350 MAG MPI?
- E
  elewisSep 9, 2025
  If your Mercury Engine has low oil pressure, here are some possible reasons: * Insufficient oil in the crankcase: Check and add oil. * Excessive oil in the crankcase: Check and remove the required amount of oil. Investigate the cause of excessive oil (improper filling, faulty fuel pump, etc.). * Diluted or improper viscosity oil: Change the oil and oil filter, using the correct grade and viscosity oil. Determine the cause for dilution (excessive idling, faulty fuel pump, etc.).
J
Jennifer PadillaSep 12, 2025
What causes insufficient temperature in Mercury Engine?
- J
  Jonathan DavisSep 12, 2025
  If your Mercury Engine has insufficient temperature, the cause may be a faulty thermostat. Replace it.
B
Brent WagnerNov 24, 2025
What causes excessive Mercury Engine temperature?
- R
  Robert OwenNov 24, 2025
  Excessive Mercury Engine temperature can be caused by: * Water inlet valve closed: Open the valve completely. * Drive belt loose or in poor condition: Replace or adjust the belt. * Seawater pickups obstructed: Remove the obstruction. * Faulty thermostat: Replace the thermostat. * Coolant level low: Check for the cause of the low coolant level and repair. Fill the system with the proper coolant solution. * Heat Exchanger Cores plugged with foreign material: Clean the Heat Exchanger. * Loss of pressure: Check for leaks. Clean, inspect, and test the pressure cap. * Kinked, collapsed, or broken hose: Straighten or replace the hose. * Transmission fluid cooler and/or engine oil cooler plugged with foreign material: Disconnect hoses from coolers and flush out with a water hose...

Summary

Identification Record

Engine and Component Identification

Form for recording engine and component identification details.

Serial Numbers

Understanding Serial Numbers

Explains the importance of serial numbers for service and product information.

Warranty Information

Owner Warranty Registration

Process for registering product warranties in the US and Canada.

International Owner Registration

Warranty registration procedures for owners outside the US and Canada.

MerCruiser Limited Warranty

Details warranty terms for MerCruiser gasoline engines, including exclusions.

MerCruiser International Warranty

Outlines warranty terms for MerCruiser gasoline engines outside the US and Canada.

3 Year Corrosion Warranty

Specific warranty coverage against corrosion failure for MerCruiser products.

Warranty Coverage

Lists services and damages not covered under the product warranty.

Transferable Warranty

Procedures for transferring the product warranty to a new owner.

Manual Guidance and Safety

Read This Manual Thoroughly

Emphasizes critical review of the manual for safe and proper operation.

General Information

Provides essential general information and highlights safety alerts like lanyard stop switches.

Operational Safety and Conditions

Exhaust Emissions and Carbon Monoxide

Advises on carbon monoxide risks and ventilation for engine exhaust.

Safe Boating Suggestions

Offers recommendations for safe boating practices and required equipment.

Conditions Affecting Operation

Discusses factors like weight distribution and boat bottom condition impacting performance.

Important Information

Operation and Maintenance

Details owner and dealer responsibilities for operation and routine maintenance.

Boat Operation Care

Covers launching, handling theft, and replacement parts for boat operation.

Maintenance and Troubleshooting

Offers DIY maintenance tips and guidance for diagnosing EFI issues.

Operation

Instrumentation Overview

Explains the function of various gauges and indicators on the boat.

Starting, Shifting, and Stopping

Guides the user through engine starting, gear shifting, and stopping procedures.

Engine Specifications

Lists technical specifications for different MerCruiser engine models.

Maintenance

Maintenance Aids and Schedule

Lists maintenance aids and refers to the schedule for service items.

Cooling System and Lubrication

Details procedures for flushing the cooling system and lubricating components.

Cold Weather Storage

Provides instructions for preparing the power package for extended storage.

Troubleshooting

Starting Problems

Helps diagnose and resolve issues related to engine starting or slow cranking.

Performance Issues

Addresses problems like rough running, misses, and poor performance.

System Faults

Covers issues like excessive temperature, low oil pressure, and transmission problems.

Owner Service Assistance

Getting Service

Guides on obtaining service from authorized dealers and service centers.

Parts Inquiries

Explains how to inquire about and order replacement parts and accessories.

Customer Service Literature

Obtaining Service Literature

Information on how to acquire manuals and literature from customer service.

Literature Order Form

Ordering Service Manuals

Form to order various manuals like operation, maintenance, and service manuals.

Mercury 350 MAG MPI Specifications

General

Engine Type	V8
Horsepower	300 HP
Ignition	Electronic
Alternator	65 amp
Cylinders	8
Displacement	5.7 L
Fuel System	Multi-Port Fuel Injection (MPI)
Emissions	EPA Certified