1991 GMC Sonoma Service and Repair Manual

This factory service and repair manual for the 1991 GMC Sonoma covers a compact pickup with three overhead-valve gasoline engines to choose between: a 2.8L V6 of 173 cubic inches, a larger 4.3L V6 of 262 cubic inches, and a 2.5L inline-four of 151 cubic inches, all naturally aspirated. Two bodies are in scope, the two-door extended cab pickup and the two-door standard cab pickup, and two trims, Base and SLE. Each engine has its own specifications, torque values and diagnostic sequences.

Engines covered

• 2.8L V6 (173 cu in) — OHV, naturally aspirated, gasoline
• 4.3L V6 (262 cu in) — OHV, naturally aspirated, gasoline
• 2.5L inline-four (151 cu in) — OHV, naturally aspirated, gasoline

Body styles covered

• 2-door extended cab pickup
• 2-door standard cab pickup

Trims covered

• Base
• SLE

Known issues on the 1991 Sonoma. What the manual has to cover is breadth — three engines across two cab styles and two trims, each with its own service figures. Engine mechanical, fuel and ignition, transmission, brake, steering, suspension and body procedures are set out system by system, along with the torque values, wiring diagrams and diagnostic routines for the 2.5L four and both V6s.