Question

You're diagnosing a hard-starting vehicle and installing a fuel pressure gauge. When the engine is shut off, the fuel pressure drops rapidly. Technician A says that a fuel injector could be leaking. Technician B says that the fuel pump may have a defective check valve. Who is correct?

A. Both Technicians A and B
B. Technician A
C. Neither Technician A nor B
D. Technician B

Answer 1

Both technicians A and B

When the engine is shut off and the pump stops running, by default, the system should hold the residual for a few minutes. If the pressure starts dropping immediately, the vehicle may have a leaking injector, a leaky fuel pump check value, problems with the FPR itself, or a leaky fuel pressure regulator.