Using a Harley Fuel Pressure Tester

There are a handful of reasons that an injected fuel system may have a low or fluctuating output.

There may be a pinhole in an aging fuel line. The fuel filter may be clogged. The fuel pump regulator may be bad. The pump itself could fail.

To perform a correct fuel pressure test, you will need to purchase, rent, or borrow a quality Harley fuel pressure tester gauge with the correct adapters to fit your Harley-Davidson output fittings. Your factory service manual is also an important tool to have nearby when diagnosing a failing fuel system.

Begin the test by removing your fuel pump fuse and running the m/c until it stalls. This will diminish or eliminate the fuel pressure in the system and allow you to safely unplug the fuel delivery line from the fuel tank. Before disconnecting this line, Mike recommends that you spray it with a little light penetrating oil. This will help you to work past any corrosion in the fitting and allow you to remove the line without damaging the O-ring inside the tank fitting. Disconnect this line by pulling up on the fitting and down on the line.

Next, you will plug in your fuel gauge and reinstall the fuel pump fuse to its correct location. Now, start your motorcycle and record the reading on the fuel gauge. Use your service manual to complete the diagnosis based on your reading.

Correct fuel pressure is vital for complete fuel system function and operation. Listen to Mike’s advice in this video—grab your fuel pressure gauge and your service manual. This is everything you need to perform this test the way the techs do at the dealerships.

You are completely prepared to perform a fuel pressure test using a Harley fuel pressure tester gauge on your Harley-Davidson.

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