How To Tell If A Motorcycle Fuel Pump Is Bad?

This guide is going to help you a lot in solving the problem of a faulty pump. It is essential because a defective fuel pump will have a negative impact on the overall performance of your motorcycle and its engine.

It might also leave you in the middle of nowhere, all stranded up. Therefore, you need to understand that you have to identify this issue before dealing with more significant issues. So, how to tell if a motorcycle fuel pump is bad? Your fuel pump is present right in your motorbike’s fuel tank, which is the case with most modern motorbikes.

Most of them are categorized as positive displacement pumps that utilize the rotating gears for accelerating the fuel flow from the pump inlet to your motorbike’s pump outlet. Various issues can happen to this entire system, and we are going to explore them briefly in this guide and continue reading.

What Can Go Wrong with Your Fuel Pump?

Problem With Your Fuel Pump

So, how to tell if a motorcycle fuel pump is bad? Various issues can happen to your motorcycle’s fuel pump. As we have mentioned above, modern motorbikes come with pumps that use rotating gears to accelerate the fuel flow from the inlet to the pump’s outlet.

Therefore, with time, these pumps can wear out. They also have seals that can go bad, resulting in internal leakage, resulting in a reduced fuel flow. A faulty pump relay can also be the cause of your motorbike’s pump failure. This relay provides a continuous current to your bike’s fuel pump when activated and working properly.

This component is a highly essential part of your motorbike’s fuel system. It covers the pump inlet of your bike and prevents any contamination with the gasoline from entering into the fuel system of your motorcycle. There is another essential component of this fuel system and its pressure regulator.

When the pump creates any excess pressure and flows, the regulator comes into play its role and limits the pressure on the pump’s outlet. It will return any excess fuel to the gas tank. The fuel pressure usually remains between 35 PSI and 65 PSI for modern bikes.

How to Tell If A Motorcycle Fuel Pump is Bad?

Do you want to know what the symptoms of a bad fuel pump are? In this section, we will have a brief look at some of the symptoms associated with a bad fuel pump in your motorcycle.

Fuel tank whining noise

Noises from fuel tank

The most common symptom and usually the first one you will experience is a whining noise coming out of your fuel tank. This symptom is always associated with a bad fuel pump in almost all cases. This sound occurs when your fuel pump has worn out or is close to wearing out altogether.

Therefore, you need to replace it as soon as possible. You need to keep in mind that a normal fuel pump will cause a slight humming sound due to the electric motor. The whining sound that a bad fuel pump creates is entirely different from his humming sound.

Motorcycle doesn’t start

Motorcycle doesn't start

If your motorbike doesn’t start, it might be due to its problematic fuel pump or relay. Your motorcycle’s engine doesn’t start because it is not getting any pressurized fuel for the pump. In this scenario, your fuel pump will fail entirely and not put out any fuel at all.

Maybe it’s just putting out enough fuel to start the engine but doesn’t keep it running. No matter what the case is. Your motorbike’s engine won’t be running properly and consistently for you to ride.

Your bike’s fuel pump relay can be at fault as well. With a faulty pump relay, current will not be sent to the electric motors, and they won’t spin the gears present inside your motorbike’s fuel pump. It will prevent the fuel pump from properly working even if the fuel pump is working perfectly fine.

There are different symptoms for a bad fuel pump relay as well, and these are as follows,

  • Your engine begins to stall if it cuts out without any prior warning. It can be directly related to your pump’s relay.
  • If your relay is not working, then your engine might not start as well. And we have discussed these issues above.
  • Maybe your fuel pump is not producing any noise at all. Even a faulty pump will make some noise. As we mentioned above, there is a serious problem with your relay if there is no noise.

Different issues can cause your motorbike not to start. A dead battery can be an issue, or a weak connection between your battery terminals can be another issue. Faulty starter motors can be another issue. If your bike is not starting for some reason, you can get some professional assistance.

Poor performance under pressure

Motorbikes need most of their fuel when you accelerate them. They also need a lot of it when you load them up. In addition to that, they also need more fuel when they travel uphill. If your fuel pump is not functioning properly, it will cause the engine to fail.

The reason is that the pump cannot keep up with what is demanded by the engine. If you are experiencing that your motorbike’s engine is shutting down or maintaining a consistent power, then your fuel pump has gone bad, and you need to replace it as soon as possible.

Gas mileage getting low

Low Gas mileage

If your motorcycle has low mileage, there can be various reasons behind it apart from a bad fuel pump. But a bad fuel pump can still impact your motorcycle’s gas mileage. If your motorbike’s pressure regulator in the fuel pump is not bypassing the proper amount of additional fuel, the additional fuel will enter the fuel system. Eventually, it will ignite, or it will go out through the engine exhaust.

Engine begins to stall at high temperature

So, how to tell if a motorcycle fuel pump is bad? Your engine might begin to stall when you are riding your motorbike in high temperatures. This will happen if your engine starts to heat up extremely fast and immediately followed by a stalling engine. It means your fuel pump is deteriorating, and you need to replace it as soon as possible.

A jump in engine speed

 increased engine speed of motorycle

You might also notice a surge in speed while cruising along without making any adjustments to the throttle. It’s another one of the symptoms of a bad fuel pump. It can be a hazardous experience and can be caused by irregularities within the pump resistance. If your engine is surging, you need to investigate your fuel pump because it will be deteriorating and immediately replaced.

How to Maintain a Fuel Pump

Maintain a Fuel Pump

If you take care of your fuel pump, it will continue to perform for a long time to come. Most of these fuel pumps are made to work for at least 50,000 miles. But with proper maintenance and care, they can last even more than that. You need to keep your gas tank more than a quarter full at all times, and it will work like a charm in increasing the lifespan of your fuel pump as well as your filter.

If the fuel level drops under that level, the pumps begin to suck additional particles and contaminants lying around at the bottom of the tank. These contaminants and particles clog the filter up, or they might pass through and damage the internals of your motorbike’s pump.

Keeping its more than a quarter will also enable the electric motor to run the fuel pump continuously immersed within gasoline. So, the motor will transfer heat with gasoline, and it won’t overheat itself to keep the wear and tear under control.


What are the signs of your fuel pump going down?

You will notice sputtering in the engine, and your engine will begin to overheat as well. There will be low fuel pressure, and your engine will experience loss of power or surging at times. Your gas mileage will deteriorate significantly, or your engine will die and won’t turn over.

Is there a way to test the fuel pump relay?

You will need a digital multimeter to its lowest range (ohms scale), or you can set it to continuity. Now connect a lead to the power circuit and link the other one to the power terminal. Your meter must show infinite resistance (open load). If it’s not there, your fuel pump relay has gone bad.

What should I do to take care of my fuel pump?

You need never allow your tank to get below one-quarter of the entire tank. The fuel pump won’t take up any contaminants lying at the bottom of the tank, and nothing will go past the fuel filter, which will remain intact as well. This is the easiest way to maintain your fuel pump.


So, how to tell if a motorcycle fuel pump is bad? It’s not that difficult because your engine will start acting up, and you will notice the difference. Just make sure that you keep your engine properly maintained at all times.

The fuel tank needs to be at least 25% filled at all times, so the fuel pump doesn’t take in any contaminants from the tank. This way, you will keep your fuel pump and the relay in optimal condition.