failing fuel pump

5 Common Signs that Your Fuel Pump is Failing

Your car’s engine needs a regular stream of fuel to keep it humming along. The fuel pump feeds fuel to the engine at a reliable rate; without this pump, your fuel would just sit in your tank, useless and inert. If you’re attentive, you can catch the symptoms of a failing fuel pump and have it repaired or replaced before it leaves you stranded on the side of the road.

What is a Fuel Pump and What Does It Do?

Photo by Hoikka1 on Wikimedia Commons / CC BY-SA 3.0.

Photo by Hoikka1 on Wikimedia Commons / CC BY-SA 3.0.

The fuel pump is a device that moves fuel from your tank to the engine, supplying the fuel at a constant pressure to ensure that your engine runs smoothly. Depending on the age of your vehicle, you may have either a mechanical or an electronic fuel pump.

Mechanical pumps run off of the motion of the engine; a diaphragm mounted to the outside of the fuel tank expands and contracts, creating a low pressure system that forces the fuel out of the tank and into the engine.

Electronic pumps are typically located inside of the fuel tank and use electromagnetic motors to force fuel to the engine at high pressure. Mechanical pumps are usually found in cars that use carburetors, and electronic pumps are usually used with fuel injection systems.

Since mechanical pumps are driven directly by the motion of the engine and contain few moving parts, they tend to be reliable and relatively easy to diagnose and fix. Most problems with mechanical pumps occur when the diaphragm is damaged in some way, throwing the pressure system off balance. Electronic pumps are typically linked to electronic control systems and contain multiple moving parts; because of this increased complexity, these types of pumps are more prone to failure. Any one of several different parts can malfunction and lead to fuel pump problems.

Symptoms of a Failing Fuel Pump

Although mechanical and electronic pumps fail for different reasons, the symptoms of failure are similar for both types of pumps. If you notice any of the common symptoms of fuel pump failure while you’re driving, you may need to have your fuel pump inspected and replaced.

1. You Might be Experiencing Fuel Pump Failure if Your Car Jerks or Sputters at High Speeds

If you’re driving at freeway speeds and notice your engine sputter or jerk, you may have a failing fuel pump. This problem is caused when the fuel pump can’t deliver a smooth flow of fuel to the engine; periodically, your engine receives only air when it was expecting to receive fuel. This interruption in fuel flow causes your engine to skip several power strokes, forcing the engine to sputter and jerk. In the early stages of failure, this sputtering may only last for a minute or so before the engine returns to normal operation. Some drivers may confuse this sign with the effects of dirty gas, but modern fuel standards make a failing fuel pump more likely.

2. Your Fuel Pump Might Be Failing if You Lose Power When Accelerating / CC0 1.0. / CC0 1.0.

If you notice that your car often loses power when you try to accelerate from a stop, your fuel pump may be in trouble. Accelerating requires more fuel, forcing your fuel pump to work harder. If your pump is failing, it may not be able to keep up with this increased demand, starving your engine of fuel as it tries to accelerate. If your car acts like it’s about to stall when you try to accelerate from a stop, you may need to have your pump inspected.

3. Your Fuel Pump Might Be a Problem if you are Losing Power While Driving Uphill or Towing a Load / CC0 1.0. / CC0 1.0.

Certain driving activities, such as climbing a hill or towing a load, place an extra strain on your engine and demand more fuel to deliver the same performance. When your fuel pump isn’t on top of its game, it often can’t keep up with this increased fuel demand. These demanding situations increase the strain on your pump, causing the weak elements to fail. With the flaws in your weakened pump exposed, it isn’t able to maintain a steady flow of fuel to the engine, resulting in a loss of power.

4. Your Fuel Pump Might Be Failing if Your Engine Surges

Photo by Ernest on Flickr / CC BY 2.0.

Photo by Ernest on Flickr / CC BY 2.0.

As your fuel pump begins to wear out, its components often wear down at different rates. When this mismatch becomes great enough, the pressure in your fuel lines can become inconsistent. In these circumstances, drivers may find their cars suddenly accelerating for a few moments even when they haven’t pressed the gas pedal, a condition known as surging.

5. Fuel Pump Failure Might Be a Reason Why Your Engine Won’t Start / CC0 1.0. / CC0 1.0.

If you ignore all of the other warning signs of a failing fuel pump, it will eventually fail completely. Once your fuel pump has finally given up the ghost, no fuel will reach your engine. You may hear your spark plugs firing when you try to start your car, but without fuel, the engine won’t be able to turn over. Of course, there could be other explanations for your engine’s failure to start besides a failed fuel pump. To confirm that your pump has failed, check the pressure in your fuel lines with a fuel pressure gauge; if it reads zero, then your pump is likely dead. You can also check your car’s fuse box; a blown fuel pump fuse is another reliable symptom of a failed pump.

What to Do If You Think Your Pump is Failing / CC0 1.0. / CC0 1.0.

If you’ve experienced any of the symptoms of a failing fuel pump, it’s best to take your car to a professional repair shop. Some of the symptoms of a bad pump can also be caused by other mechanical problems, so the repair shop will perform a number of tests to isolate the true cause of the problem. If no other sources seem likely, they’ll confirm the fuel pump diagnosis with a number of procedures.

Most shops will begin by checking your car’s electrical system, especially the fuses that regulate power to your fuel system; blown fuses are fairly common and are cheap to fix. If the fuses aren’t damaged or fixing them fails to solve the problem, mechanics will next check the voltage on the pump itself. Using a multimeter, the mechanics will measure the voltage drop on different ends of the fuel pump to determine whether there are any problems within the pump itself.

Your fuel pump is an integral part of your car, supplying your engine with a steady supply of the fuel it needs to keep you moving. Like any device, however, fuel pumps can and do eventually wear out after thousands of miles of use. If your car struggles with weak or inconsistent power, it may be time to replace the fuel pump on your car.

Have you ever had to deal with a failing fuel pump?

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