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Fuel Pumps for BMW 325i

A failing fuel pump can seriously impact the fuel efficiency and performance of your vehicle. If your BMW 325i has a faulty fuel pump, the solution is usually replacement of the unit. You can find the right pump for your car and learn more about it here.

How do fuel pumps work?

Fuel pumps are pumps specially designed to move fuel, whether gasoline or diesel, from your car's fuel tank to the combustion chambers in its engine. Most modern automobiles have two fuel pumps: one mounted inside the fuel tank and one mounted on the engine. Fuel injection engines have a high-pressure fuel pump that can move fuel at a high volume into the engine's intake manifold or fuel injectors. The fuel tank pump assists by moving fuel out of the tank and into the fuel line.

What types of fuel pumps are available?

Fuel pumps come in a few different designs, some of which have become obsolete. Over the years, they've been refined to just a couple different variants, which are often both present in newer cars.

  • Fuel tank pump: These pumps are mounted inside a car's fuel tank and provide the back pressure for the feed into the engine's combustion chambers. They usually double as the fuel level sensor as well, using a plunger or float to measure how much fuel is remaining in the tank.
  • High-pressure pump: These pumps are specially designed to feed fuel to each of the engine's combustion chambers at the pace the engine is running at. They are precision components that must keep to the correct timing and amount of fuel for the engine to run smoothly.
How can you diagnose a faulty fuel pump?

A failing pump can be difficult to diagnose because the symptoms can seem like more common problems like a bad ignition coil or spark plug. Here's a couple of common symptoms you may experience with a bad fuel pump.

  • Misfiring, shuddering, or stalling: When a high-pressure pump begins to fail, it may be due to clogging or a failing fuel pump mechanism. Clogging can cause misfiring because it will stop fuel from reaching one or more cylinders, but the others will continue to fire normally. If the pump weakens or stops intermittently, you may experience shuddering and stalling, as the engine isn't able to run at all.
  • Runs poorly on the freeway: If you notice that your engine runs poorly at high speeds but runs fine in town, the problem may be the fuel pump in the tank. Because it isn't providing enough back pressure to deliver the amount of fuel needed on the freeway, that's when you notice problems with the engine.
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