The Mazda 6 is a mid-sized, front engine, front wheel drive sedan introduced by Mazda in 2002. Variations include a five-door hatchback and a five-door station wagon. The Mazda 6 was named one of the year's ten best vehicles in 2003 by "Car and Driver" magazine. Like any vehicle, however, your Mazda 6 may develop problems in areas such as fuel delivery. If it suddenly seems sluggish while accelerating or getting poor gas mileage, you may have a problem with your fuel delivery system that you should check out.
Investigate possible fuel delivery problems in the Mazda 6 if the engine starts running rough, stalls in traffic or won't start at all. These can be other signs of a fuel delivery issue.
Relieve fuel system pressure. Take off the fuel filter cap and disconnect the fuel pump relay next to the engine. Start the Mazda 6 and let the engine run until it stalls from lack of gasoline. Turn the ignition off and disconnect the negative battery cable.
Disconnect the fuel pressure sensor vacuum hose. Check for fuel in the line. If there is fuel present in the line, the fuel delivery problem is likely caused by a faulty fuel pump pressure regulator. If there is no fuel in the line, reattach the vacuum hose and continue with the fuel delivery diagnostic.
Twist off the fuel pressure test port cap and attach a pressure gauge to the fuel pressure valve. Reconnect the negative battery cable, start the engine and let it idle. Check the gauge. It needs to read 33 psi. Disconnect the vacuum hose again and check the gauge again. This time it needs to read 43 psi. Pressure that's too high indicates a malfunctioning pressure regulator. A low pressure reading indicates a clogged fuel filter or a broken fuel pump that needs to be replaced.
Cut the engine, relieve system pressure again and remove the negative battery cable so you can safely remove the fuel filter and check for clogs.
Loosen the filter fittings and the mounting bracket. Remove the fuel filter.
Examine the filter for clogs and replace it with a new one if necessary. If there are no clogs, the fuel delivery problem is probably caused by a faulty fuel pump.