Technician A says a rich air/fuel ratio may be caused by low fuel pump pressure. Technician B says a rich air/fuel ratio may be caused by a defective engine coolant temperature sensor. Who is correct?

Question

Quizplus · Accepted Answer

A rich air/fuel ratio is typically caused by too much fuel or not enough air. A defective engine coolant temperature sensor can cause the engine control unit to think the engine is colder than it is, leading to a richer mixture. Low fuel pump pressure would typically cause a lean condition, not a rich one.

Technician a Says a Rich Air/fuel Ratio May Be Caused