Fuel Injection System - Diesel: Testing: MVS

1985 Cadillac Fleetwood Base, 4D LimousineSECTION MVS
  1. Allow engine to warm up. Shut off engine. Remove air cleaner cover. Place MAP sensor with leads and vacuum hose attached aside. Remove air crossover and install covers. Disconnect HPAA solenoid lead and MVS harness.
  2. Install MVS Test Harness (J-34678) and MVS Adapter Harness (J-64678-50) (Not needed on C series with internal EGR). Install tachometer. Start engine. Set parking brake and shift into "D". With alternator connected, set idle to 600 RPM (all V8), 675 (C Series with external EGR), 650 all others.
    Fig 1: C Series With Internal EGR Check MVS voltage as shown.
    G3349
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.