1993–1999 MerCruiser 4.3L (262 CID) Marine Engine Service Manual #18 (P/N 90-823226-1)

Mercury Marine Service Manual No. 18 covers the 1993–1999 MerCruiser MCM 4.3L (262 CID) V-6 balance-shaft marine engines listed above, including carbureted and EFI Gen+ Alpha/Bravo variants. This is the 1996 publication, identified as 90-823226--1.

Supplied as one 643-page PDF in English.

• Engine service: Engine removal and installation, cylinder-head and rotating-assembly overhaul, balance-shaft service, and separate Gen+ repair specifications.

• Ignition and charging: Thunderbolt IV/V troubleshooting, distributor service, starter-motor repair, Mando alternator testing, and instrumentation diagnosis.

• Carburetors and EFI: MerCarb/Weber overhaul, VST and Cool Fuel service, diagnostic trouble-code charts, and throttle-body injection tests.

• Cooling and exhaust: Seawater pickup pump output testing, closed-cooling pressure checks, heat exchanger repair, and manifold, elbow, riser, and collector service.

• Power steering and maintenance: Pump replacement, hose routing, system bleeding, engine coupler spline lubrication, winterization, and recommissioning.

• Wiring and test references: Alpha/Bravo harness diagrams, ECM connector charts, system-specific diagnostic flowcharts, and component torque and inspection tables.

Written for Mercury Marine dealers, mechanics, and service personnel familiar with the recommended procedures and the required standard and special tools.

Engine Repair and Installation

Engine removal and installation are separated into Alpha and Bravo procedures, with mounting requirements and engine-to-gimbal bearing alignment instructions. The manual specifies Quicksilver alignment tool 91-805475A1 and explains how forcing the tool can damage the gimbal bearing or engine coupler.

Internal repair covers cylinder-head and valve conditioning, hydraulic roller lifters, crankshaft and bearing inspection, and balance-shaft gears. Gen+ head-bolt angle tightening and intake-manifold sequences are distinguished from standard-engine procedures.

The tables give cylinder bore limits, piston-to-bore clearances, and crankshaft journal dimensions, with main bearing clearances separated into production and service limits. Timing-chain deflection checks are also included.

Ignition, EFI Diagnosis, and Wiring

Thunderbolt IV and V sections cover ignition timing and fault isolation. Starting and charging chapters include PG260/Delco-Remy starter overhaul and Mando alternator component tests; instrumentation coverage extends to gauges, senders, and audio warnings.

EFI fault tracing: Scan-tool and non-scan charts cover code reading and clearing, no-start conditions, fuel delivery, and Idle Air Control (IAC) operation. ECM connector/pin-voltage charts help separate wiring and sensor faults before an Engine Control Module (ECM) or Knock Sensor (KS) module is condemned.

Specified diagnostic equipment includes Quicksilver scan tool 91-823686A2. Alpha/Bravo harness views distinguish VST and Cool Fuel installations; the four-part EFI wiring diagram supports circuit tracing.

An IAC service caution identifies pintle handling that can damage the valve's worm drive.

MerCarb, Weber, and Fuel Delivery

MerCarb two-barrel and Weber four-barrel sections cover disassembly, inspection, reassembly, and float, choke, accelerator-pump, and idle adjustments. Vapor Separator Tank (VST) fuel-flow diagrams and throttle-body exploded views show how the EFI fuel components are arranged.

Bodensee/BSO-SAV: Dedicated coverage explains the emissions-version Weber WFB carburetor, Positive Crankcase Ventilation (PCV), Ported Vacuum Switch (PVS), and propane-assisted idle setting.

Working around inboard fuel vapors and high-output ignition systems carries inherent fire and shock risks. Follow the manual's ventilation and electrical-isolation precautions.

Seawater Cooling, Closed Cooling, and Exhaust

Water-flow diagrams distinguish coolant-fed and raw-water-fed exhaust manifolds. Tests address thermostat operation, heat-exchanger leaks and blockage, and head-gasket leakage; belt-driven seawater-pump repair covers both one-piece and two-piece pump bodies.

Exhaust service includes manifold/elbow inspection, riser installation, and collector shutter replacement. The Alpha drive's internal seawater-pump repairs are referred to the separate Stern Drive Service Manual.

Power Steering and Service Limits

Pump, pulley, hose, and cooler replacement procedures sit alongside serpentine-belt routing views. The dual-engine priority-valve kit 79691A1 has its own installation instructions.

This is an engine manual: sterndrive overhaul and the steering system testing/repair referenced in Section 8A require the appropriate separate Stern Drive Service Manual.

PDF Search, Navigation, and Included Pages

The page total includes the five-page cover/front-matter block twice, 23 section dividers, and 27 intentionally blank pages. Embedded bookmarks link to sections and procedures, and the main text supports search; some labels inside diagram images are not searchable. Small wiring labels are best read with zoom.