1977–1989 Mercury Mariner 45–220 HP 2-Stroke Outboard Service & Repair Manual

This service and repair manual covers the listed 1977–1989 Mercury and Mariner two-stroke outboards, including inline and V6 powerheads with carbureted or EFI fuel systems. It provides teardown, inspection, reassembly, and adjustment procedures organized by engine and component design.

• Powerhead repair: Removal, internal inspection, and rebuilding for original inline, redesigned inline, and V6 engines, with component clearances and tightening sequences.

• Fuel systems: Overhaul procedures for carburetor types A–E, fuel-pump testing, 2+2 accelerator-pump operation, and EFI diagnosis and component replacement.

• Ignition and electrical: Thunderbolt CD testing, timing and synchronization, charging-circuit diagnosis, starter-motor repair, and ignition wiring diagrams.

• Oil injection: Auto Blend and Advanced Oil Injection troubleshooting, warning-circuit checks, oil-pump adjustment, and system service.

• Lower units and cooling: Cam-Shift and E-Z Shift overhaul, gear shimming, backlash checks, water-pump replacement, and thermostat testing.

• Power trim and tilt: Hydraulic and electrical troubleshooting, bleeding, and component service for the manual’s A, B, and C system designs.

• Controls and recoil starters: Commander control-box disassembly and reassembly, plus hand rewind starter overhaul, spring-tension adjustment, and shift-interlock checks.

It is suited to mechanics and experienced owners who understand two-stroke operation and can use the specified measuring equipment; the EFI section recommends professional testing of suspected electronic components before replacement.

Carburetion, EFI, and Oil Injection

Carburetor identification illustrations distinguish Tillotson/Walbro Mercarb, center-square-bowl, WME, side-bowl/back-drag, and V6 dual-float designs before their individual overhaul sections.

Jet-size/elevation charts support selection for the applicable carburetor and operating altitude. Rough-idle troubleshooting also considers intake-manifold leaks and unequal cylinder compression.

The 100 HP and 115 HP four-cylinder 2+2 system has its own accelerator-pump fuel-flow diagram. EFI coverage includes a fuel-flow and sensor-signal schematic, injector tests, pump-ground diagnosis, vapor-separator service, and throttle-position-sensor adjustment.

The EFI electric booster pump and ECU are sealed replacement components, not internally rebuildable units. Opening the booster pump destroys its airtight seal and creates a fuel-system hazard.

Auto Blend warning-horn checks distinguish versions with and without an electronic module. Advanced Oil Injection coverage follows the remote tank, engine-mounted reservoir, check valves, and mechanically driven metering pump through diagnosis and service.

Thunderbolt Ignition and Electrical Diagnosis

Separate procedures address distributor-type Thunderbolt CD ignition and flywheel CD ignition with a coil for each cylinder. Stator, trigger, coil, and switch-box tests help isolate ignition faults before components are replaced; idle-stabilizer and spark-advance-module checks are also covered.

Timing and carburetor synchronization are divided by powerhead configuration and V6 serial-number group. The electrical chapter adds rectifier tests, harness inspection, and Bosch, Delco Remy, and Prestolite starter-motor repair.

Powerhead Overhaul and Cooling

The engine chapters distinguish original crankshaft-mounted reeds from the redesigned inline reed-block arrangement, with separate V6 rebuilding procedures. Piston and cylinder specifications, reed-stop data, and staged tightening sequences accompany inspection and assembly.

Flywheel removal calls out the crankshaft protector cap C-91-24161; the manual warns that incorrect pulling or hammering can damage the crankshaft, bearings, or flywheel. Cylinder inspection also distinguishes steel sleeves from chrome-plated bores, which cannot be treated as ordinary honing or rebore jobs.

Thermostat and poppet-valve diagnosis addresses overheating and restricted cooling flow. Compression checks, spark-plug evaluation, seasonal maintenance, and winter storage are covered elsewhere in the manual.

Gearcases, Trim Systems, and Controls

Lower-unit identification separates Cam-Shift Types I and II from E-Z Shift, including differences between older driveshafts and the Alpha/MR design. Gear-contact-pattern illustrations and backlash tables support the matching shimming procedure, helping avoid applying one gearcase design’s setup to another.

Trim/tilt service distinguishes twin-cylinder, three-cylinder, and single-cylinder arrangements. Type B and C wiring drawings support electrical fault tracing; the Type B hydraulic pump is a replacement-only component. Commander control wiring accompanies mechanical control-box service.

Hand rewind starter coverage distinguishes the two designs used on the four-cylinder 45 HP and 50 HP engines. The appendix also supplies metric conversions and lower-unit capacity and gear-ratio tables.

Pressurized fuel, trim hydraulics, and a raised outboard require the service precautions described for each system.

A Preview of Cooling and Oil-Warning Specifications

These examples are a small selection of the manual’s cooling-system and warning-circuit data.

For larger outboards using the described water-pressure gauge, the water-pump check specifies at least 5 psi at full throttle, including turns and other maneuvers. The thermostat bench test specifies an opening temperature of 140–145°F.

For Auto Blend units with the directly battery-fed warning horn, the positive supply lead contains a 0.5-amp fuse. The troubleshooting section treats this circuit separately from versions using an electronic module.

Searchable Text, Bookmarks, and PDF Contents

Search and diagram detail: Embedded OCR text supports searching, and bookmarks lead to the chapters, appendix, and wiring section. Recognition errors can affect searches for numbers and labels. Small wiring labels require zooming.

The download contains one printable English-language PDF with 609 pages: 576 chapter pages, a one-page Engine Finder, five contents pages, and a 27-page appendix. All of these pages are included in the total.