Fuel Pump Pulsator Operation:
A small accumulator mounted between the fuel pump outlet and the fuel pressure regulator. Most are mounted in the fuel tank between the fuel pump outlet and the fuel supply line. It reduces the fuel pressure variations that occur as the fuel injectors open and close, and to reduce operating noise. Usually built-in grommets seal the unit to the tubing ends. Some are made into a section of flexible fuel line located in the engine compartment. Failure of the in-tank units would result in increased noise or loss of fuel pressure or volume, depending on the type of failure, the external units could develop fuel leaks detectable by smell or visual inspection. The pulsator isn't a routine maintenance item, although replacing the in-tank unit is recommended with a fuel pump replacement.