THE DISSECTION OF AN ELECTRIC FUEL PUMP

Fuel pumps may come in huge boxes when you order them for your vehicle. Instead of just replacing the fuel pump, you need to replace the entire module or hanger. There are some units that are "open", which allows you to see the pump, sock, filter and wiring, and there are some that are "closed", which shows a large plastic cylinder.

FUEL PUMP DISSECTION

A electric fuel pump is composed of several parts that are contained in a cylindrical metal tube. The inner workings of a fuel pump may never be seen, but knowing what they contain can give you some insight into why they fail. The following components are usually found in fuel pumps:

• In the event of an engine shutdown, the check valve in the fuel pump holds pressure so that the engine will start quickly when you start your vehicle again.
  
  
• In the event of a fuel blockage, the relief valve prevents the fuel pump motor from overheating, thereby protecting the fuel delivery system
  
  
• Radio frequency interference filter: This prevents radio interference from interfering with the operation of fuel pumps.
  
  
• A brush provides low-resistance operation to electric motors. Fuel delivery becomes more difficult as the brushes wear out. The pump may eventually stop working due to bad brushes.
  
  
• A balanced armature helps to minimize fuel pump vibrations and noise.
  
  
• Filter for internal combustion engines. A fuel filter is located inside most fuel pumps to remove any debris from the fuel tank.

FUEL PUMP MODULES

The pump itself cannot be replaced if you are quoted the price of an entire unit when purchasing a fuel pump. Some manufacturers sell the entire unit or just the pump itself, but keep in mind that other parts do wear out and malfunction over time, so you may save money by replacing the entire unit rather than just the pump.

The following parts are usually found in a fuel pump module:

• A fuel pump positive wire, a fuel pump negative wire, a sender positive wire, and a sender negative wire make up the wiring at the top. A harness plug connects the fuel pump unit to the wiring harness.
  
  
• An outlet on the fuel module receives fuel from the fuel supply line, which connects to the fuel pump.
  
  
• Unused fuel can be returned to the tank through the fuel return line. A return system is not used by all fuel pumps.
  
  
• Your fuel level is determined by a fuel level sender on the fuel pump. Senders read float positions and send the information to fuel gauges. Fuel gauges will not function properly if the float is broken or the arm of the float is bent.
  
  
• There is a fuel pump located here. A fuel pump module from the inside
  
  
• Fuel pump socks are filters located at the bottom of the pump. Before debris reaches the pump and fuel lines, it strains most of it from the bottom of the tank.

A malfunction in one of these parts can prevent your fuel pump from working at all, from working intermittently, or from working at the wrong pressure. A vehicle that doesn't have the correct fuel pressure will run poorly, since fuel injectors require a certain amount of pressure to feed fuel to the engine, which is typically between 40 and 60 psi.