Mercury MerCruiser 262 CID (4.3L) Inboard Engine Service Manual (P/N 90-861328-1)

• Official Mercury Marine factory service manual, P/N 90-861328--1, issued November 1999 as Service Manual No. 25. The supplied file is a 790-page PDF covering GM V-6 262 CID (4.3L) marine engines.

• Model coverage includes MCM 4.3L, MCM 4.3LH, and MCM 4.3L EFI engines in Alpha and Bravo applications. Separate belt-routing information is provided for S/N 0L619083 and below and S/N 0L619084 and above, the break associated with the later alternator arrangement.

• Covers engine removal, installation, and alignment, followed by internal engine repair procedures for the cylinder heads and valves, hydraulic roller lifters, pistons and connecting rods, crankshaft and bearings, camshaft, timing chain, balance shaft, oil pump, and rear main seal.

• Electrical sections address PG260-series starter overhaul, Thunderbolt V ignition diagnosis and timing, Mando and Delco-Remy charging-system testing and alternator repair, instrumentation, senders, switches, and the audio warning system.

• Fuel-system coverage spans the Mercarb 2-barrel, Weber 4-barrel, SAV1 emissions configuration, and throttle-body EFI. Procedures include carburetor disassembly and adjustment, Cool Fuel system repair, injector and throttle-body service, fuel-pressure testing, and EFI sensor replacement.

• Diagnostic material includes MEFI 1 and MEFI 3 connector and circuit identification, scan-tool specifications, trouble-code charts, intermittent-fault diagnosis, system and ignition checks, and symptom-based troubleshooting for hard starting, hesitation, stalling, loss of power, backfire, and detonation.

Coverage and Shop Use

Mercury states that this manual was written for dealer mechanics and company service personnel. It assumes prior familiarity with MerCruiser or comparable marine-engine service, normal mechanic’s hand tools, and the specified Mercury or supplier tools. That makes it a shop-level overhaul and repair manual rather than introductory training material.

Both seawater-cooled and closed-cooled installations are covered. The cooling chapters include seawater-pump output testing and overhaul, thermostat testing, heat-exchanger repair, system pressure testing, cylinder-head-gasket leak checks, draining, flushing, and Alpha/Bravo-specific flow diagrams. Exhaust-manifold, elbow, riser, shutter, and bullhorn service is followed by drive-shaft, output-shaft housing, bearing-support, and power-steering pump repair.

Engine and Fuel-System Depth

The engine chapter goes beyond routine maintenance. It provides bearing- and piston-failure analysis, cylinder-head and valve conditioning, valve-guide bore repair, valve-spring testing, crankshaft inspection, timing-chain deflection checks, and balance-shaft service. Component-specific torque tables, wear limits, clearances, fluid data, and inspection specifications accompany the repair procedures.

Carburetor sections contain exploded views and full overhaul coverage, including float, choke, accelerator-pump, idle-mixture, and high-altitude calibration work. The SAV1 chapter adds emissions-system troubleshooting and its propane-assisted idle-setting procedure. EFI coverage explains ECM operation, speed-density control, spark and fuel management, connector service, electrostatic-discharge precautions, and the individual MAP, TP, ECT, IAT, knock, and IAC circuits.

Schematics, Test Charts, and Special Tools

Representative visual references include the Starting and Charging Harness, Fuel and Ignition System Harnesses, Dual Station Wiring, MEFI 1 and MEFI 3 wiring-system diagrams and ECM connector charts, Alpha/Bravo cooling-flow and draining diagrams, and component exploded views for the carburetors, throttle-body EFI, starters, alternators, drive shaft, and power-steering pump.

The manual identifies the required diagnostic equipment and part numbers, including the Quicksilver Digital Diagnostic Terminal 91-823686A2, Fuel Pressure Gauge Kit 91-16850A5, EFI Timing Tool 91-805747A2, Timing Light 91-99379, and Quicksilver Alignment Tool 91-805475A1.

Repair Cautions and Scope

Engine alignment is one area where the factory procedure matters: the manual warns that substituting or forcing the alignment tool can damage the gimbal bearing or engine coupler. It also requires replacement EFI injectors to carry the identical part number and calibration; a similar-looking injector with the wrong flow rate can cause performance problems or ECM damage.

Alpha and Bravo references apply to engine installation, belt routing, cooling, draining, capacities, and related interfaces. This publication is not a complete Alpha or Bravo sterndrive overhaul manual, and propeller service is referred to separate sterndrive literature.

Fuel, ignition, and electrical work requires battery isolation and a well-ventilated engine compartment because an improperly installed marine component or an electrical spark can ignite fuel vapor. Cooling water must be supplied whenever an engine-running test is performed to avoid seawater-pump and overheating damage.