A four-stroke cycle auxiliary diesel engine fuel cam has shifted from its original position during maintenance. To ensure correct timing of the fuel pump, the intake and exhaust valves should be in what position when approaching top dead center for injection?

Correct Answer: Option A — Intake and exhaust valves closed

When timing a four-stroke diesel fuel injection cam, the technician must verify the piston is approaching Top Dead Center (TDC) on the compression stroke. At this exact point, both the intake and exhaust valves are fully closed to trap the air charge.