When a fuel pump pressure drop is diagnosed, there are some essential tasks to perform in order to locate the source of potential problems within the overall fuel delivery system. The operating pressure for a normal fuel pump generally varies from 35 to 65 psi depending on the make and model of the vehicle. If the fuel pressure is any lower than this, it could cause the engine to lose performance and stall and could also make restarts difficult. Auto research shows that inadequate pressure accounts for almost 20% of fuel system symptoms, so diagnosing is a necessity.
The first thing to do is properly check the fuel pressure with a dependable gauge. Connect the gauge to the service port on the fuel rail, then turn the ignition key to "on" but do not start the engine. The gauge will read the chosen pressure. If the pressure is low, check for drop in pressure when running the engine. Wear and tear on a fuel pump means the internal parts function less efficiently which can cause a pressure drop. Studies have reportedly revealed that a potential rate of 30% fuel pumps can experience performance loss due to utilization for period of just five years.
The next is the fuel filter. A restricted filter can choke off fuel supply across it, resulting in substantial pressure drop frequently falling through 10 to 15 psi. Use a filter that has not been replaced in the last 30,000 miles can lead to problems with fuel delivery. The American Automobile Association (AAA) reports that lack of maintenance to the fuel filter is among top causes of fuel system failures.
Keep An Eye On Electrical Stuff An erratic or weak connection could impede the flow of electricity to your fuel pump, which would keep it from functioning properly. Inspect the fuel pump relay and associated wiring harness for any damage. Investigation revealed about 25% of fuel pump failures as having failed due to electrical issues. Electrical resistance should be less than 0.1 ohms; if it is higher, chances are you have a problem.
Also, put the fuel lines and injectors into consideration. Blockage or some kink in the fuel line will narrow flow, so as to pressure. A study by the Society of Automotive Engineers shows that one in every six fuel delivery problems is caused by a line blockage. Pressure also will drop when the compressor needs maintenance, if there are any leaks, cracks, or corroded connections.
Finally, if you test the fuel pump directly, this may reveal some important clues. If the pump works at volume above 60 psi and it goes below to 30 psi when under load, then it means that it is in a faulty condition. They can fail for a variety of reasons such as wear, heat and contamination, usually falling between 100-200,000 miles before they quit working altogether. According to automotive professional John D. McClusky, "knowledge of the fuel system in your vehicle is crucial for maintaining its performance."
Checking these components one by one will allow you to come with the true cause of a fuel pump pressure drop. An effective Fuel Pump ensures that your vehicle is always operating within its best efficiency and reliability.