The accumulator is a pressure reservoir that has a diaphragm with a spring behind it to hold a small amount of pressurized fuel in the system to smooth out spikes in delivery and to provide residual pressure. It is generally located in the area of the fuel pump and fuel filter. It will generally have a large line connected to the fuel line on the discharge side of the fuel pump and a small vent line attached to a steel nipple on the back side (in some cases this will be vented to the atmosphere) and usually vented back to the fuel tank or fuel intake on the fuel pump. Disconnect this vent line and plug it so it does not leak and run the fuel pump. While the fuel pump is running if fuel leaks out of the steel nipple the accumulator is bad and must be replaced.