The Ford Focus is a compact car that debuted in North America in 2000 as a sedan, three-door and five-door hatchbacks and wagon. The line of Focus vehicles was narrowed over time to only the sedan and coupe. The Focus made Car and Driver magazine's "Ten Best" list for 2000, 2001, 2003 and 2004.
Check the fuel delivery system of the Ford Focus if the engine is running rough, hesitating, stalling out while driving or not starting at all.
Release fuel system pressure. Remove the fuse for the fuel pump from the battery junction box. Start the engine and let it run until it stalls and quits. Crank the engine for five seconds to release the pressure. Disconnect the negative battery cable.
Disconnect the vacuum line from the fuel pump pressure regulator and check for fuel in the line. Refer to the owner's manual for the line's location if you aren't sure which one it is. If there is fuel present in the line, the engine problems are likely caused by a faulty fuel pump pressure regulator. If there is no fuel in the lines, reattach the vacuum line and continue with the Ford Focus fuel delivery diagnostic.
Twist off the fuel pressure test port cap and attach a fuel pressure test gauge to the fuel pressure valve. Reconnect the negative battery cable and start the engine. Let it idle and then check the pressure gauge. It needs to read between 35 and 60 pounds per square inch. Pressure that's too high is an indicator that the pressure regulator is malfunctioning. Pressure that's too low indicates that the fuel filter is clogged or that the fuel pump is malfunctioning and needs to be replaced.
Cut the engine. Relieve system pressure again and remove the negative battery cable again so you can safely remove the fuel filter to check for clogs. Raise the Focus up and access the fuel assembly. Removing the evaporative emissions (EVAP) vapor line, the fuel filter lines, the fuel filter bracket assembly and finally the fuel filter. Visually check the filter for clogs and replace it with a new one if necessary. If there are no clogs, the fuel delivery problem is likely caused by a faulty fuel pump.
Install or reinstall the filter. Install the fuel filter into its bracket assembly. Connect the fuel filter lines and the EVAP vapor line. Lower the Focus and reconnect the negative battery cable. Start the engine and visually check for any leaking fuel.