Everything You Need to Know About Motorcycle Fuel Pumps

Fuel pumps measure the correct quantity of fuel and deliver the same to the engine cylinder at the right time. The exact quantity of fuel that’s supplied to the cylinder depends on the load and speed requirements. This is what makes these pumps so integral — and it’s also why you should attend to motorcycle fuel pump repairs sooner rather than later.

Since it’s so essential to your motorcycle, we’ll talk a bit about the design of the fuel pump. The more familiar you are with this component, the more easily you’ll be able to identify the motorcycle fuel pump repairs you need.

The Inner Workings of a Fuel Pump

The plunger is one of the most important parts of a fuel pump. This is what’s responsible for injecting the gas to the cylinder. This plunger works through a cam and tappet mechanism at its bottom. There are many plungers in the fuel pump, one for each engine cylinder. So, if there are four engine cylinders, the fuel pump should have four plungers. Each plunger comes with a vertical groove that’s rectangular in shape.

The working mechanism starts due to the pressure of the fuel against the spring. This lifts the delivery valve off its seat and the fuel is moved to the injector. To start off, the plunger is at the bottom and the fuel is forced into the barrel. Next, the plunger is pushed up by the movement of the cam and this closes both the parts. In this movement, the fuel located just above it gets compressed and, in turn, this lifts the delivery value. Eventually, the fuel goes to the injector.

The plunger moves even higher up due to the pressure and the fuel gets transported to the upper part of the plunger. Thus, fuel is delivered at every stroke of the plunger and it is in accordance with the spill port’s communication. This communication can be adjusted by changing the position of the helical groove that in turn, can be adjusted with the rotation of the plunger.

Ergo, this is how the fuel pump injects fuel to the engine cylinders. Now that you know how this component works, let’s look at a few common motorcycle fuel pump repairs and their corresponding problems.

Symptoms of a Fuel Pump Problem

Here’s a look at some of the common motorcycle fuel pump problems and the symptoms you should watch out for.

  • Whining Noises: One of the first symptoms you see from motorcycle fuel pumps is the whining noise. In fact, an old pump may produce a whirring or whining sound while running while the newer ones will give out a humming sound. These sounds indicate very low fuel levels, a damaged motorcycle fuel pump, or poor quality of fuel inside the pump.
  • Sputtering Sounds: One of the most common things that warrant might a motorcycle fuel pump repair is a sputtering noise, especially when you drive at high speeds. This could often be caused by dirty fuel filters or a faulty fuel pump that’s unable to supply a steady stream of fuel to the engine.
  • Surges: Sometimes, the vehicle behaves as if you’ve pressed on the gas pedal even if you haven’t. This causes a random surge in speed and is extremely dangerous — as it can get your vehicle out of control. Again, this could be due to a dirty filter or a faulty fuel pump.
  • Low Mileage: If you think you’re filling fuel more often than usual, you should consider motorcycle fuel pump repairs. It is often because a valve inside the fuel pump may not open at the right time and this can cause more fuel to pour into the injection system. Also, the excess fuel that gets injected doesn’t get stored, so this wastes the fuel.

These are some of the common problems you may face related to fuel pumps when you own a motorcycle. Since research shows that four-fifths of the most common automotive repairs are related to durability, you’ll want to prioritize regular maintenance and sourcing the highest quality parts (and repairs) for your vehicle.