by Christopher Howard

Created on: March 06, 2009

It's 7:45AM and you are supposed to be at work at 8. You get in your car and insert the key into the ignition. Low and behold, the engine just cranks and sputters. You shut off the key and try again. This time it starts but only runs for 10 seconds before it sputters and dies. With disgust you slam the door and call your boss and explain that you are going to be late to work. The tow truck finally shows up at 10AM and you finally get to work at 10:45. This situation happens all too often and is preventable.

Preventative maintenance on your vehicle can prevent you from being stranded. One component that can fail by not performing regular maintenance is your car's fuel pump. The most common reason fuel pumps fail (besides age and wear) is a plugged or restricted fuel filter. The fuel pump is forced to work harder in order to keep the fuel pressure within specification. To troubleshoot a fuel pump, you must first understand the types of pumps and how they work. This article is geared toward readers who are familiar with automotive terms and are mechanically inclined.

There are two basic types of fuel pumps. First, the oldest type of fuel pump is the mechanical style fuel pump. This type of fuel pump is mounted on the side of the motor and is driven by a push rod activated by the engine cam shaft. This type of fuel pump has a diaphragm that when worked back and forth, creates suction, drawing the fuel in and pushes it toward the carburetor.

The second type is the electric fuel pump. The electric fuel pump can be located in the fuel tank, in line with the fuel lines under the vehicle, or both. Electric fuel pumps typically have an electric motor inside that runs the pump.
The pumps typically run at a static pressure which requires a fuel pressure regulator to manage the fuel pressure.
They are activated by a fuel pump relay which turns on the fuel pump and primes the system when the ignition is turned to the on position. The relay can go bad causing the fuel pump to be blamed.

When a fuel pump starts to go bad, you may experience lack of power, no start, bucking, sputtering, or the engine may stop running. To trouble shoot this, automotive professionals will usually use a fuel pressure regulator to measure the fuel pressure. However, there are simpler ways to tell if you fuel pump is bad.

Mechanical fuel pumps are simple to troubleshoot. Most of the time you will experience lack of power or your engine will not run at all.
However, the most obvious way to tell if your

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