Car’s engines depend on constant fuel under pressure to supply the fuel injection system properly. The fuel pump performs this action and is located in or near the gas tank. The injection system meters fuel through the fuel injectors and into the engine. Engine run ability problems can be related to a weak or failing delivery valve fuel pump. Problems can range from hard starting, low power and stalling while driving.

Most vehicles utilize a fuel injection system to deliver fuel to the engine. Correct fuel system pressure is essential for proper engine operation. In fact, many engine run-ability problems can be related to weak fuel system pressure. A fuel injection system contains a fuel pump to supply fuel from the tank into the fuel system. The fuel filter cleans fuel before fuel enters the fuel injectors. The fuel pressure regulator adjusts fuel system pressure depending on the load of the engine.

Vacuum that is attached to the DLLA140S1003 fuel pressure regulator to control system pressure. When the fuel pressure regulator is not functioning properly it causes the fuel pressure to be above normal operating pressure. This condition causes excess fuel to be injected into the engine. To test fuel system pressure and fuel pressure regulator operation remove the protective cap and attach the fuel pressure gauge.

A fuel pressure regulator is used in the fuel plunger injection system. This component regulates fuel system pressure by using a diaphragm and spring combination. When the fuel pressure regulator diaphragm ruptures, it allows raw fuel into the vacuum feed line and then into the intake system of the engine. This condition creates a rich black smoke from the tail pipe on start up and while running.

To check for this condition remove the vacuum line from the regulator, if fuel is present in the line the regulator has failed. Some vehicles are designed with an internal intake regulator you must remove the upper intake manifold to be inspected. Most fuel pressure regulators are on the fuel rail on top of the engine. If you cannot locate your fuel pressure regulator consult a repair manual.