What Does a Fuel Pump Do?

At AAMCO Minnesota we work on many different makes and models of cars and trucks. We repair everything from air conditioning to transmissions, and fuel pumps are right in there with all the things about cars that we know and fix.

When your fuel pump starts to go, there are some warning signs that you can look for – but first let’s look at how a fuel pump works. It’s obviously an important part of any vehicle. It pumps the fuel from the fuel tank to the engine. If it goes out, your car doesn’t go – period. That’s when you have your car towed to your local Minnesota AAMCO.

In basic terms, an engine needs gasoline to run. That gasoline is stored in a tank at one end of the car. It has to somehow get to the engine at the other end of the car so it can be burned to create power to move the car. Image - mechanic fixing fuel pumpThe fuel pump basically forces the gas from the tank to the carburetor or fuel injector. If it’s not working properly, you can end up with either too little or too much gas being sent to the engine. This is due to too much or too little pressure in the fuel line. This leads to performance issues and eventual break down.

Types of Fuel Pumps

There are two types of fuel pumps: mechanical and electronic.

Mechanical Fuel Pump

A mechanical fuel pump uses the rotation of the engine to operate itself. It’s usually mounted on the outside of the gas tank and is generally less likely to fail than an electronic fuel pump – and easier to diagnose and repair. (We’ll get into that later.)

Electronic Fuel Pump

With the phasing out of carburetors in new cars and the use of fuel injection systems, a new kind of fuel pump was needed – the electronic fuel pump. Because mechanical fuel pumps can’t generate the pressure necessary for fuel injection systems to work. The electronic fuel pump is located in the gas tank itself. Because of its location and the how it works with the fuel injection system – all of which is regulated by a computer – it can be challenging to diagnose a problem and is sometimes more difficult and costly to repair.

Malfunctions in the fuel pump itself, however, are straightforward and result from issues in either the pumping or the creation of pressure. Here are some common signs that the fuel pump has a problem.

Signs of Fuel Pump Problems

There are a few symptoms that indicate a fuel pump is malfunctioning and that you should take your car to a Minnesota AAMCO mechanic for diagnosis and repair.

  • Loss of Power
    If your car just does not feel as “strong” as it should, the fuel pump is probably not pumping fuel as effectively as is needed. Not enough gas is getting to the engine as it works to climb a hill or pull a load. An older or weakened fuel pump just can’t keep up with the demand, which leads to power loss, particularly under stressful conditions.

    Eventually, this power loss will occur under normal operation. As you accelerate from a stop, the engine will sputter, causing the car to shudder and jerk as it tries to move forward. It feels as if the car is going to stall, but then it recovers and continues to accelerate smoothly.

  • Engine Sputter
    At high speed the engine will sputter or begin to jerk. This will occur after several miles of normal, smooth driving, then return to normal for a while, then happen again… and so on. Though many people blame it on “dirty” gas or a different brand or lower octane, the reality is most likely that the fuel pump can’t supply a constant stream of fuel to the engine at a consistently proper pressure, which causes the engine to intermittently sputter.
  • Engine Surge
    The opposite of sputtering and loss of power is known as engine surge, or surging. Your car will be moving at a normal, consistent pace and will suddenly surge forward, as if you stepped on the gas. This is simply due to age and wear and tear. The fuel pump has irregular electric current in its motor, which means it doesn’t have the power it needs in order to maintain the proper pressure through the fuel line. This is obviously necessary to maintain steady, safe speeds.
  • Engine Won’t Start
    Last, but not least, the symptom we all dread – the engine just will not start. Ignoring the aforementioned signs will result in this final condition. There is no fuel reaching the engine. You might hear a clicking sound at the engine, or nothing at all. This could be something as simple as a blown fuse; but if not, you’ll need to get to an AAMCO Minnesota mechanic to have the line pressure checked and a complete diagnostic done to identify the problem.

How to Fix Fuel Pump Issues

If you have a fuel pressure gauge, you can run a pump pressure test. This will help you determine if there is correct, adequate, and consistent pressure being put out by the pump to push fuel to the engine. The required pressure varies for different kinds of vehicle tasks, so it’s usually best to take your car to a mechanic to run the test.

At AAMCO Minnesota our mechanics know what causes fuel pump failures, what to look for, and how to fix them. A faulty fuel pump can affect the performance and lifespan your car’s engine, so be proactive and schedule an appointment at your local Minnesota AAMCO for an inspection. There could be a lot more going on, so the AAMCO multi-point inspection is always a good idea.

Other Articles About Car Maintenance & Repair

Reasons Your Car is Not Driving Smoothly

Signs Your Car Needs a Mechanic

Car Maintenance on a Budget


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Our mission is to provide the best auto repair and maintenance in Minnesota. With 6 convenient locations and nearly 50 years in business, you can count on your locally-owned Minnesota AAMCO Center to provide expert transmission repair, brake service, tune-ups, oil and filter changes, electrical system repair, fluid service, and much more for your car, truck, or SUV.

Our comprehensive 36-step ProtectCheck® Inspection, expert technicians, and no-nonsense pay-only-for-what-you-need approach makes us the most trusted name in car care. Come see why people who know go to AAMCO.

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