1990–1996 Mazda 121 Workshop Manual - Volume 1 of 2 (P/N 1249-10-90J)

• Document and vehicle coverage: Two-volume, 771-page PDF set for the Australian-market Mazda 121, dated October 1990 with Mazda document number 1249-10-90J. Volume 1 contains 390 PDF pages; Volume 2 contains 381. The stated application begins with VIN JM0 DB1031 00 100001.
• Engine and lubrication work: Covers tune-up checks, compression testing, timing-belt and cylinder-head-gasket service, crankshaft oil-seal replacement, engine removal, stand mounting, full disassembly, inspection, repair, reassembly, and installation.
• EGI-S and engine electrical diagnosis: Provides symptom-based fuel-injection troubleshooting, self-diagnosis checks, ECU and sensor testing, fuel-pressure procedures, plus battery, charging, ignition, alternator, distributor, and starter service.
• Manual drivetrain and chassis repair: Details B5M-R transaxle removal and overhaul, differential and shift-mechanism service, clutch work, drive shafts, wheel hubs, steering, brakes, wheel alignment, and suspension.
• Body, canvas top, and climate systems: Includes doors, glass, locks, trim, instruments, lighting, wipers, audio, canvas-top electrical and mechanical repair, heater service, and air-conditioning diagnosis and component service.
• Important scope limits: The supplied volumes do not contain the Section K F4A-EL automatic-transaxle repair chapter or the separately published Section Z Wiring Diagram, form 5181-10-90J. F4A-EL technical data, special-tool listings, and system-specific circuit diagrams are still included.

Powertrain, Maintenance, and Mechanical Repair

The engine material is built around the B3 inline four-cylinder, 1323 cc, belt-driven 16-valve OHC engine and its EGI-S fuel-management system. Scheduled service includes pre-delivery inspection plus valve-clearance, drive-belt, oil-and-filter, cooling, ignition, fuel-and-emission, clutch, brake, steering, suspension, drive-shaft-boot, and chassis-fastener checks.

Repair depth goes well beyond routine maintenance. The engine chapter covers on-vehicle timing-belt, cylinder-head-gasket, and crankshaft oil-seal work, followed by engine removal and internal overhaul of the cylinder head and valve train, camshaft, pistons and rods, crankshaft and bearings, oil pump, and cooling components. The clutch chapter addresses pedal and cable adjustment, cover and disc inspection, release parts, pilot bearing, and flywheel service.

For manual-transaxle cars, Section J documents the B5M-R structural layout and power flow, oil service, removal, disassembly, inspection, adjustment, reassembly, and installation. It also covers gears, shafts, synchronizers, bearings, the differential, shift rods and forks, interlock parts, oil seals, bearing preload, and shim selection. On automatic cars, this set supplies F4A-EL specifications and tool references, but not the complete automatic-transaxle repair section.

Diagnostics, Chassis, Body, and A/C

The EGI-S chapter is organized for fault isolation. Its diagnostic index addresses starting faults, unstable idle, stalling under accessory loads, hesitation, surge, loss of power, backfire or detonation, fuel or exhaust odor, oil consumption, and poor fuel economy. Supporting material covers the ECU, injectors, crank-angle and airflow sensors, throttle and oxygen sensors, relays, switches, evaporative-emission components, fuel-pressure testing, and the Mazda Self-Diagnosis Checker/System Selector workflow.

Axle and steering coverage includes front hubs and steering knuckles, rear axles, tripod-joint drive shafts, wheel bearings, manual rack-and-pinion steering, and engine-speed-sensing power steering, with hydraulic bleeding and pressure testing. Brake and suspension chapters address master-cylinder and booster diagnosis, front-disc and rear-drum service, the parking brake, wheels and tires, alignment, struts, springs, lower arms, stabilizers, the rear torsion-beam axle, and trailing-arm bushings.

Body material covers the hood, doors, window regulators, glass, locks, trunk lid, mirrors, trim, seats, seat belts, instruments, lighting, wipers, rear-window defroster, horn, and audio. A dedicated canvas-top section adds circuit diagnosis, switch and motor testing, limit-switch and control-unit checks, guide-rail and frame work, adjustment, and hole and tear repair. Heater and A/C coverage includes diagnostic checklists and flowcharts, heater and blower units, the cooling unit, condenser, receiver/drier, pressure switch, magnetic clutch, and compressor service.

Specifications, Diagrams, Special Tools, and Repair Cautions

Technical Data tables collect component-specific torque specifications, fluid grades and capacities, pressure-test data, clearances, wear limits, adjustment values, and electrical test specifications. Particularly useful illustrations include the EGI-S system diagram, vacuum-hose-routing diagram, B5M-R power-flow view, starting-system circuit diagram, canvas-top circuit diagram, and A/C connector-location and diagnostic flowcharts.

The Special Tools section identifies Mazda SSTs by number. Examples include the 49 0107 680A engine stand, 49 9200 020 V-ribbed-belt tension gauge, and 49 SE01 310A clutch centering tool. Additional listings cover transaxle, brake, axle, steering, suspension, diagnostic, and A/C equipment.

The manual flags assembly errors that can cause real damage. Its oil-pan notes warn against prying at the cylinder-block joint and explain that old sealant left on reused bolts can crack the bolt hole. The steering chapter warns that hammering the shaft during steering-wheel removal can collapse the steering column.

Brake hydraulics, fuel-pressure work, steering, compressed springs, and refrigerant service require appropriate equipment and safe workshop practices. Work beyond your training or available tooling should be handled by a qualified automotive technician.