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24V Cummins Basic Diagnostics

(1 review)
Mopar1973Man

By Mopar1973Man

Use this article to diagnose driveability problems existing when a hard Diagnostic Trouble Code (DTC) is not present.

Engine Difficult To Start Or Will Not Start
(Exhaust Smokes While Cranking)

  • Check for low fuel level.
  • Check for low battery voltage.
  • Check for plugged fuel filter.
  • Check for poor quality or improper grade of fuel.
  • Check fuel tank venting.
  • Check for low fuel pressure.
  • Check for air in fuel system.
  • Check for fuel lift pump malfunction.
  • Check for fuel inlet restriction.
  • Check for kinked or restricted fuel line.
  • Check for kinked or restricted fuel return passage or fuel return line.
  • Check for incorrect injectors.
  • Check for incorrect injector shim thickness.
  • Check for injector malfunction.
  • Check for fuel connector leaking fuel.
  • Check for engine speed sensor and/or circuit malfunction.
  • Check for moisture in harness connectors or corroded terminals.
  • Check for internal engine damage.
  • Check for air intake restriction.
  • Check for exhaust restriction.
  • Check for fuel inlet temperature too high.
  • Check valve lash adjustments.
  • Check for ignition switch output voltage low and/or open.
  • Check starting accessories for cold weather such as engine block heaters or fuel heaters (if equipped).
  • Check fuel pump overflow valve.
  • Check for low engine cranking speed.
  • Check for electrical noise.

Engine Difficult To Start Or Will Not Start
(No Exhaust Smoke While Cranking)

  • Check for low fuel level.
  • Check for poor quality or improper grade of fuel.
  • Check for plugged fuel filter.
  • Check fuel tank venting.
  • Check for low fuel pressure.
  • Check for air in fuel system.
  • Check for fuel lift pump malfunction.
  • Check for fuel inlet restriction.
  • Check for fuel injection pump supply voltage open or low voltage.
  • Check for kinked or restricted fuel inlet line.
  • Check for kinked or restricted fuel return passage or fuel return line.
  • Check for incorrect injectors.
  • Check for incorrect injector shim thickness.
  • Check for injector malfunction.
  • Check for fuel connector leaking fuel.
  • Check for engine speed sensor and/or circuit malfunction.
  • Check for moisture in harness connectors or corroded terminals.
  • Check for Sentry Key Immobilizer Module (SKIM) issues.
  • Check for low battery voltage.
  • Check for ignition switch supply voltage low or open.
  • Check for electrical noise.
  • Check fuel injection pump.
  • Check ECM.
  • Check for internal engine damage.

Engine Surges At Low Or High Idle

  • Check for low fuel level.
  • Check for plugged fuel filter.
  • Check for poor quality or improper grade of fuel.
  • Check for fuel tank venting malfunction.
  • Check for low fuel pressure.
  • Check for air in fuel system.
  • Check for fuel lift pump malfunction.
  • Check for restricted fuel inlet.
  • Check for kinked or restricted fuel inlet line.
  • Check for kinked or restricted fuel return line.
  • Check for incorrect injectors.
  • Check for incorrect injector shim thickness.
  • Check for malfunctioning injectors.
  • Check for leaking fuel connection.
  • Check for faulty fuel injection pump.
  • Check for malfunctioning or out of calibration accelerator pedal.
  • Check for damaged vibration damper.
  • Check for engine speed sensor and/or circuit malfunction.
  • Check for vehicle speed sensor and/or circuit malfunction.
  • Check for incorrect transmission clutch operation.
  • Check for dragging brakes.
  • Check for transmission malfunction.
  • Check for cooling fan cycle time malfunction.
  • Check for turbocharger malfunction.
  • Check for Bus communication malfunction.
  • Check for moisture in harness connectors or corroded terminals.
  • Check for internal engine damage.
  • Check for electrical interference (noise).
  • Check for excessive load at idle.
  • Check for incorrect or malfunctioning clutch.

Engine Surges Under Load Or Operation Range

  • Check for low fuel level.
  • Check for plugged fuel filter.
  • Check for poor quality or improper grade of fuel.
  • Check for fuel tank venting malfunction.
  • Check for low fuel pressure.
  • Check for air in fuel system.
  • Check for fuel lift pump malfunction.
  • Check for fuel inlet restriction.
  • Check for kinked or restricted fuel inlet line.
  • Check for kinked or restricted fuel return line.
  • Check for incorrect injectors.
  • Check for incorrect injector shim thickness.
  • Check for malfunctioning injectors.
  • Check for leaking fuel connection.
  • Check for malfunctioning or out of calibration accelerator pedal.
  • Check for engine speed sensor and/or circuit malfunction.
  • Check for vehicle speed sensor and/or circuit malfunction.
  • Check for incorrect transmission clutch operation.
  • Check for dragging brakes.
  • Check for transmission malfunction.
  • Check for cooling fan cycle time malfunction.
  • Check for turbocharger malfunction.
  • Check for Bus communication malfunction.
  • Check for moisture in harness connectors or corroded terminals.
  • Check for internal engine damage.

Excessive Black Smoke

  • Check for dirty or plugged air filter.
  • Check for restricted/leaking air intake system.
  • Check for DTCs set or intermittent DTC malfunctions.
  • Check for ECM or PCM not calibrated properly.
  • Check for exhaust system restriction greater than specification.
  • Check for poor fuel quality.
  • Check for fuel injection pump malfunction.
  • Check for fuel injector malfunction or leak.
  • Check for fuel return system restriction.
  • Check for intake manifold restriction.
  • Check for manifold air pressure (boost) sensor circuit malfunction.
  • Check for raw fuel inside intake manifold.
  • Check for turbocharger air intake restriction.
  • Check turbocharger for excessive carbon build-up on compressor wheel and/or diffuser vanes, wheel
    clearance out of specification or damage

Excessive Blue Exhaust Smoke

  • Check for dirty or plugged air filter.
  • Check for air intake system restriction.
  • Check for air leak in intake between turbocharger and intake manifold.
  • Check for restricted exhaust.
  • Check for restricted turbocharger drain tube.
  • Check for plugged crankcase ventilation.
  • Check for worn or defective valve stems, guides or seals.
  • Check for improperly gapped, worn or broken piston rings.
  • Check for excessive cylinder bore wear.
  • Check for cylinder damage.
  • Check for piston damage.
  • Check for turbocharger failure.

Excessive White Exhaust Smoke

  • Check for air in fuel system.
  • Check for coolant leak into combustion chamber.
  • Check for DTCs set or intermittent DTC malfunctions.
  • Check for block heater malfunction in cold weather.
  • Check for engine coolant temperature sensor malfunction.
  • Check for ECM not calibrated properly.
  • Check for clogged or defective fuel filter.
  • Check for poor fuel quality.
  • Check for fuel heater or fuel heater temperature sensor malfunction.
  • Check for malfunctioning or loose fuel injector.
  • Check for fuel injection pump malfunction.
  • Fuel injector restricted or blocked fuel injection or supply lines.
  • Check for fuel transfer pump malfunction.
  • Check for Intake/exhaust valves not adjusted properly (tight).
  • Check for intake manifold heaters or intake manifold air temperature sensor malfunction.
  • Check for internal engine damage.
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