What should be done before starting the engine after installing a new fuel filter?

• A. Prime the fuel system
• B. Bleed air from the fuel lines
• C. Check oil pressure
• D. Run the engine at idle

Answer: (A)

Priming the fuel system is needed after installing a new fuel filter because air trapped in the filter and lines can prevent fuel from reaching the injectors. By priming, you push fuel through the new filter and hoses and remove air, building proper fuel pressure so the engine can start smoothly. After you prime, the engine should fire as normal; without priming, you may crank without starting due to air pockets in the fuel system. Bleeding air from the lines is related to this process, but priming is the step that ensures the system is filled and pressurized before starting. Checking oil pressure or running the engine at idle before it starts isn’t appropriate pre-start actions.