P1171 – Fuel System Lean Under Load (Ford)

Description

P1171 Ford indicates the engine is running lean under load.

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Symptoms

  • Hesitation
  • Poor acceleration
  • Knocking

Causes

  • Weak pump
  • Vacuum leak
  • MAF contamination

Diagnosis

  • Check fuel trims
  • Inspect MAF
  • Measure fuel pressure

Repair

  • Repair leaks
  • Clean MAF
  • Replace pump