Mercury Mercruiser Marine Engine Number 23, GM V-8 454 CID (7.4L)/502 CID (8.2L) service manual (90-861326--1)

• Original OEM publication (Technical Code / Part No. 90-861326--1, Edition March 1999) straight from the manufacturer.
• 1,027 pages (Book 1 of 2) packed with original manufacturer specifications, reference data, and exploded views.
• Covers various V8 sterndrive and inboard variants of the Gen. VI and L-29 series, including the 454 Mag MPI and 502 Mag MPI.

Marine System Coverage

This documentation breaks down the core systems of GM V8 marine engines. It provides exact service and maintenance data, including specific intervals for standard and Horizon models. You will find detailed technical breakdowns of drive components, engine removal procedures, and inboard transmissions like the Velvet Drive or Hurth. The manual dives deep into complex electronic fuel injection (MPI and EFI) setups. It also covers both closed freshwater cooling and conventional seawater systems, exhaust configurations, and hydraulic power steering. Need to trace a fault? The electrical wiring diagrams, harness routing details, and systematic trouble code diagnostics for the engine control unit give you the foundation to understand the entire onboard electrical system. Always exercise extreme caution and adhere to standard shop safety practices when handling marine fuel components or working near moving drives to prevent injury.

Specifications and Engine Characteristics

Verifying compatibility is crucial. This text provides the extensive spec tables and operating data required by technically minded owners and marine mechanics. It lists precise machine characteristics, such as the exact 4.47 x 4.00-inch bore and stroke for the 8.2-liter engines. Propshaft horsepower figures are detailed across the board, ranging from 275 HP for strict SAV1 Lake Constance standards up to 415 HP. High-density reference values are packed into every section. You get exact tightening specs, like the 31 Nm (23 lb-in) requirement for specific power steering hose fittings. Fluid capacities, detailed electrical reference values for all sensors, ignition timing specs, and essential connector pinouts are all clearly laid out. The publication even calls out specialty equipment, like the Quicksilver Alignment Tool (91-805475A1), to help you match the right documentation to your exact boat project.