Last Updated on September 26, 2023 by Chase Manhattan
Harley Davidson motorcycles are known for their strong performance and reliable engines. However, just like any other vehicle, they can sometimes encounter problems. One of the most common issues experienced by Harley Davidson owners is related to general fuel injection problems, but more specifically the fuel pump. In this article, we’ll explore some of the most common fuel pump problems and their symptoms, as well as how to diagnose and fix them, whether you’re a DIY enthusiast or prefer to take your bike to a dealer.
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What’s The Most Common Harley Davidson Fuel Pump Problem?
While there are numerous signs & symptoms of a bad or failing fuel pump, there is one predominant failure seen in Harley Davidson motorcycles:
Harley Davidson Fuel Pump Not Coming On
One of the most common problems is a fuel pump issue where it fails to turn on. This can result in your motorcycle not starting, or stalling while running. There are several potential reasons for this issue, including a blown fuse, faulty fuel pump relay, or a dead fuel pump motor. Checking and replacing the fuse or relay, if necessary, is a relatively simple fix. However, if the fuel pump motor itself has failed, you’ll likely need to replace the entire fuel pump assembly.
Other Potential Signs Of Harley Davidson Fuel Pump Problems
In addition to the fuel pump not coming on, there are several other symptoms that may indicate a problem with your Harley Davidson‘s fuel pump. These can include:
Sputtering On Acceleration
If your motorcycle sputters when accelerating, it could be a sign that the fuel pump is not providing a consistent flow of fuel to the engine. This can result from a failing fuel pump, a clogged fuel injector or fuel filter, or damaged internal components within the pump assembly.
A weak or failing fuel pump can make it difficult for your motorcycle to start, as it may not be providing enough fuel pressure to the engine. This can be caused by a malfunctioning fuel pump relay, a clogged fuel filter, or a failing fuel pump motor.
Surging At Idle or Constant Throttle (Bouncing RPMs)
Surges in engine speed, also known as a high idle, while maintaining a constant throttle or during idle can be indicative of a fuel pump issue. This typically occurs due to erratic resistance within the fuel pump motor, which can cause fluctuations in fuel delivery.
Reduced Fuel Efficiency
A failing fuel pump can lead to reduced fuel efficiency, as it may not be providing the proper fuel pressure to the engine. This can result from a malfunctioning fuel pressure regulator or a clogged fuel filter, both of which can impact fuel delivery.
Overall Reduced Performance
If your Harley Davidson motorcycle is not performing at its optimal level, it could be due to a fuel pump issue. A malfunctioning fuel pump can cause the engine to struggle under heavy loads, making it difficult to maintain speed or accelerate.
Sporadic or Rough Idle (Dying RPMs – Bogging)
A rough or sporadic idle can be a sign of a failing fuel pump. This is often caused by fluctuations in fuel pressure, resulting in an inconsistent flow of fuel to the engine. This can lead to stalling, bogging, or a rough-running engine.
If your motorcycle stalls randomly while running, it could be due to a fuel pump problem. In many cases, this is caused by a clogged fuel filter or a failing fuel pump motor, both of which can impact fuel delivery.
Fuel Pump Whining (As It’s Dying)
A high-pitched whining noise coming from the fuel tank can be a sign that your fuel pump is failing. This noise is often caused by the fuel pump motor struggling to maintain the proper fuel pressure, resulting in increased stress on the motor.
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How To Test and Diagnose A Harley Davidson Fuel Pump Problem
If you’re not comfortable diagnosing or fixing a fuel pump problem on your own, it’s always a good idea to take your motorcycle to a professional Harley Davidson dealer or repair shop. They’ll have the specific knowledge, tools, and expertise to properly diagnose and repair any fuel pump issues your motorcycle may be experiencing. However, for the handier of us all, you can test and diagnose your fuel pump following the step by step instructions below.
Step 1: Gather Necessary Tools and Materials
Before you begin diagnosing and repairing your Harley Davidson fuel pump, gather the necessary tools and materials, including:
- Fuel pressure gauge
- Fuel pump repair kit (if needed)
- Safety glasses
Step 2: Identify Symptoms
Pay close attention to the symptoms your Harley Davidson motorcycle is exhibiting. Common signs of a faulty fuel pump include:
- Hard starting or failure to start
- Poor performance or stalling
- Reduced fuel efficiency
- Strange noises coming from the fuel tank area
Step 3: Check for Power and Ground at the Fuel Pump
For a greater understanding of A Harley Davidson charging system, I recommend taking a glimpse of our troubleshooting guide which will cover all the components of the system prior to any diagnostics.
- Turn off the motorcycle, and ensure it is in a stable position.
- Locate the fuel pump by referring to your Harley Davidson’s service manual.
- Using a multimeter, check for power and ground at the fuel pump’s electrical connector. If there is no power or ground, inspect the wiring, fuses, and relays for any issues. Repair or replace as necessary.
Step 4: Test Fuel Pressure
- Connect a fuel pressure gauge to the fuel rail, following the manufacturer’s instructions.
- Turn on the motorcycle, and observe the fuel pressure reading.
- Compare the reading to your Harley Davidson’s service manual specifications. If the pressure is too low or too high, this may indicate a problem with the fuel pump.
Step 5: Inspect Fuel Pump Components
- Turn off the motorcycle, and disconnect the battery.
- Remove the fuel pump from the tank, following the instructions in your Harley Davidson service manual.
- Inspect the fuel pump components, such as the filter, strainer, and wiring. Look for any signs of damage, wear, or clogging.
Step 6: Repair or Replace the Fuel Pump
If you have determined that the fuel pump is the cause of the issue, you can either repair it with a fuel pump repair kit or replace it with a new pump.
- If repairing the pump, follow the instructions provided in the repair kit to replace any damaged or worn components.
- If replacing the pump, install the new pump according to your Harley Davidson service manual.
Step 7: Reassemble and Test
- Reinstall the fuel pump into the tank, and reconnect all electrical connections.
- Reconnect the battery, and turn on the motorcycle.
- Test the motorcycle for proper performance. If the issue persists, consult a professional mechanic for further diagnosis.