Signs Your Fuel Pump is Failing
In the old days a fuel pump was a mechanically operated rubber diaphragm that physically pulled fuel from the tank and pushed it towards the carburetor. These systems ran at very low pressures of about 4 to 6 PSI (pounds per square inch).
On modern vehicles the fuel pumps are often tank mounted and electrically powered. They produce much higher fuel pressures than their old-fashioned counterparts. In this article we will discuss the operation and some warning signs that problems are developing. Learn what you can do to support a long, healthy life from your own fuel pump and things to look out for if you need to replace one.
Fuel Pump Location and Operation
Electric fuel pumps can be located inside or outside of fuel tanks. On most domestic vehicles you’ll find the in tank version so we will focus on these types here. Although be aware that some manufacturers mount the fuel pump in-line between the tank and injectors. On rare occasions you’ll find vehicles that have both, in tank and in-line systems working together.
Many automotive manufacturers install fuel pumps in tank as a way of keeping it lubricated and cool. Gasoline is a petroleum product and provides excellent lubrication for the internal components. Another advantage of this location is pressurizing the entire fuel line from its beginning at the tank to the end where it feeds the injectors. Line pressure is important to reduce evaporation from heat better known as vapor lock. Some find the in tank location an interesting choice since electric motors are known for small sparks between the armature and brushes. Spark and fuel would not appear to be a safe situation but the location is safe because there is not enough oxygen to support ignition or combustion inside the tank.
Fuel Pump Problems and Warning Signs
Fuel pump problems are usually indicated by low system pressure or completely inoperative units causing a vehicle not to start. Many manufacturers include an easy access port on the fuel rail near the injectors. This is where you connect a fuel pressure gauge to test system pressure. Evaluating obtained readings is an excellent way to diagnose problems. Car makers will supply specifications and an operating range. Low readings could be a sign of a weakening pump or a clogged fuel filter.
In tank fuel pumps will have a screen mounted at the inlet where it draws in fuel. This is known as a sock. In addition to this fine mesh screen manufacturers add a fuel filter mounted in the rail to stop any debris from working its way up to the injectors. Clogging of the screen or the filter can reduce pressure and cause low readings. Although not as common as low test readings it is also possible for the pressure to be too high. This usually indicates a faulty pressure regulator or an obstructed return line. Vehicle specific auto repair manuals will provide specifications along with diagnostic procedures for various results.
Noisy pump operation is another warning sign that there may be problems developing. Manufacturers go to great lengths to insulate the passenger compartment from normal noise created by electric pumps. Insulating mats between the tank and the body absorb most sounds. As the internal components begin to wear these parts can generate increased noise levels that surpass the sound deadening materials ability to suppress it. Being able to suddenly and easily hear the fuel pump running could be a sign of developing problems.
How to Protect Your Fuel Pump from Premature Failure
Many automobiles go to the junkyard with the original fuel pump installed. This is a good goal to shoot for. When it becomes necessary to replace this auto part there are a lot of variables involved that can reduce the quality of the replacement. This can cause a situation where repeat fuel pump failures haunt particular vehicles.
Some of the variables include the replacement parts themselves. There are many manufacturers of varying quality that are producing these replacement pumps. Select new original manufactured parts as opposed to re-manufactured aftermarket when possible. Another variable is the location of the fuel tank. Some automakers make it very difficult to remove. Difficult procedures increase chances of human error that can cause problems requiring additional service appointments to correct.
Now that we are motivated to protect this vital component lets finish with how we can achieve this. As mentioned above, cooling and lubrication are provided by the fuel sitting in the tank. Running the vehicle out of fuel and running the pump in a dry state can greatly reduce its lifespan. It is important to keep fuel in the tank. The amount is not as important as completely running out, as even a small amount is good enough for cooling and lubricating.
The other thing we can do is to religiously replace our fuel filters at its recommended mileage. When this filter becomes a restriction the pump has to work harder to feed the injectors and maintain proper pressures. Another thing we can do is to add a locking gas cap to prevent vandalism. Things can be put in the tank that will destroy a healthy fuel pump. Controlling what is going in the tank allows for maximum life out of the originally installed fuel pump.