electric fuel pump
Simply put, the purpose of a fuel pump is to draw fuel from the fuel tank then to deliver it to a fuel injector or carburetor. All vehicle engines operate by way of a mechanical pump or via a fuel injected pump. Chances are if your engine requires a mechanical pump it is quite old and has fuel pumping at a low pressure from a fuel tank to the carburetor. Most likely your engine uses a fuel injected pump as do most modern engines and transfers fuel at high pressure into the fuel injection system from an electrical pump mounted either inside or outside the fuel tank.
Typical Fuel Injection System
Mechanical Pumps
Before electronic fuel injection, most carbureted vehicle engines used mechanical fuel pumps to move fuel from the fuel tank into the fuel sections of the carburetor. However, more recently, as vehicle engines shifted from carburetors to fuel injection, mechanical fuel pumps are increasingly being replaced with electric fuel pumps. This is because electronic fuel injection systems generally run more effectively at higher fuel pressures than mechanical pumps
Fuel Injected Pumps
Fuel injection pumps, which are usually electric, are located within the fuel tank or near the gas tank in order to maintain a steady amount of fuel and to utilize the fuel in the tank to cool the pump. Fuel injection pumps are part of an electronic system, which means that they are controlled by a computer system that oversees key factors including the air to fuel ratio, the contents of the exhaust gases and the actual position of the throttle.
When Fuel Pumps Fail
There are a couple of reasons why your fuel pump will fail, be it electric or mechanical. Electric fuel pumps can experience wear and tear on the armature, brushes or bearings. In addition, roller gears and pump vanes can also wear down. This will cause a gradual loss of pressure and poor engine performance. Some causes of fuel pump failure can include rust or dirt because they can get past the inlet filter sock, which is designed to filter these sediments. When this occurs the fuel pump will break down because of contaminants that have infiltrated the pump and cause it to jam. This will result in having the motor overheat and burn out. Sometimes a fuel pump will not work properly if it is not given the proper amount of fuel needed to run adequately. Your vehicle’s fuel pump relies on fuel running through it to cool and lubricate it. Starving your fuel pump for fuel can cause your vehicle's fuel pump to fail prematurely. Mechanical fuel pumps usually rupture the diaphragm that is used as the pump, and will leak a small amount of fuel externally (from the weep hole) or just not have pressure.
How to Replace a Fuel Pump Outline
To replace your fuel pump first start with a nearly empty tank then make sure that the transmission is in park, the parking brake is activated and the front wheels are secured. Next elevate the vehicle with at least two jack stands for safety and disconnect the filler neck from the fuel tank itself. This can be done by removing the hose clamp that holds the hose to the fuel tank. Then remove either the rear or front two bolts that fasten the fuel tank to the vehicle and gently lower one side of the tank. At this point you should be able to reach the fuel line and wiring connectors, which should be disconnected prior to removing the two other bolts. Now you can remove the fuel pump from the tank and insert a replacement pump. When replacing your fuel pump opt for the same type of pump. Installing a different type of replacement pump can create difficulties. Your fuel pump is a vital component of the fuel system, so its electrical draw, flow and pressure characteristics must be in specification with the remainder of your vehicle’s system. Having a different fuel pump substituted for another can result in a mismatch, creating durability, noise and, most importantly, engine performance problems. Always check the system fuel pressure after a fuel pump replacement. It is also a good idea to replace the fuel filter and the fuel pump relay when replacing the pump, due to the extra amperage an old pump can draw through the relay.
Fuel Pump Best Practices
When selecting the correct fuel pump for your vehicle’s engine, be sure to have the engine size, year, make and model of your vehicle. Having this information handy will allow you to obtain the correct fuel pump specifically calibrated to your engine's performance specifications. In addition, make sure the fuel tank is clean. Although this should be self evident you must inspect the fuel tank carefully to make sure there is no dirt or rust inside and clean it as needed. Be sure to check the fuel lines for cleanliness as well at this point. The reason for these examinations is to prevent the most prevalent cause a fuel system failure, dirt. Take an extra few extra minutes and replace the fuel filter when replacing the pump.
Basic Maintenance
The main preventive maintenance you can do with a fuel injection system is to keep your throttle body clean and your fuel filter changed.
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