To check the fuel pressure you need a fuel pressure gauge. You can purchase one from any auto parts or store. There is a fitting on the fuel supply manifold (tube that supplies fuel to the injectors). You remove the cap and screw the adaptor for the pressure gauge onto the fitting. Start the engine and read the pressure. Then stop the engine and read the pressure and leave theengine stopped and the gauge connected for about 30 minutes. The pressure should hold without dropping for at least 30 minutes. If it drops rapidly or is too low, you may have a faulty pressure regulator, fuel pump, or check valve. The pressure regulator has a vacuum line that runs to the intake manifold. If the regulator is bad, it can leak fuel through the diapragm into the manifold and further the problem by "flooding" the engine after sitting for a while.