How to Repair a Fuel Line in a Car

by Paul Vaughn
gas pump image by jedphoto from

Fuel lines develop leaks when part of the line rubs against anything metal under the vehicle. Typically the frame rail is responsible for most of the rubbing damage. Fuel line fittings can also be a cause of a leaking fuel line if they were cross threaded when they were installed. Fuel line leaks cannot be repaired and need to be replaced with a new line. Cutting parts out of the damaged line and replacing with fittings at the leak will cause the lines to be too short to mount properly.

Step 1

Position drip pans under each fuel line connection and under any leaking fuel. Wear safety glasses when making a visual inspection of the damage. Depending on how low your vehicle sits, you may need to use a hydraulic jack and jack stands to raise the vehicle high enough to get underneath on a creeper.

Step 2

Use your open end box end wrench, turning counter clockwise, to loosen the fuel line connections. Allow any residual fuel to drain onto the drip pan. Disconnect the fuel line female fitting from the male fitting on both of the ends of the fuel line.

Step 3

Use your flat-tip screw driver to loosen any mounting clamps holding the fuel line in place. Remove the fuel line and perform a visual inspection of the entire fuel line. If you find rubbing damage, locate the source of the rubbing under the vehicle. Look for shiny spots where the fuel line was mounted.

Step 4

Visually inspect the fuel line fittings. Look for stretched or damaged threads that need to be replaced before installing the new line. Install the new fittings at this time by using your open end box end wrench and turning counter clockwise to unscrew the female fitting. Install the new fittings with the same wrench, turning clockwise until the fitting is snug. Do not overtighten the fittings, as this will cause the threads to stretch and fail to make a good seal.

Step 5

Purchase new fuel lines from a parts store. Give the year model of your vehicle so you can get a fuel line that is already bent to match the old fuel line. You can also buy straight fuel line and use a tubing bender to match the new line with the old one. You will need new ferrals at each end of the new line. Allow 1/16 of an inch to stick out from the ferral so that the fitting makes a good seal.

Position the new line so that it conforms to the location of the mounting clamps and end fittings. Use your flat-tip screw driver to secure the clamps to the fuel line. Use your open end box end wrench to tighten both fuel line fittings. Do not overtighten the fittings, as this will prevent them from making a good seal.


  • Do not overtighten fittings as this will cause leaks.
  • Make sure all the residual fuel has drained from the line you are working on.
  • Use a backup wrench to hold the male fitting in place while unscrewing the female fittings.
  • Dispose of residual fuel in the drip pans following OSHA guidelines.


  • If any fuel gets in your eyes, flush with clean water for 15 minutes and call 911.
  • Do not do this procedure near an open flame such as a gas water heater.
  • Be careful when loosening the fuel line fittings not to make a spark. Fuel vapors are highly flammable.

Items you will need

  • Safety glasses
  • Drip pans
  • Open end box end wrench
  • New fuel line
  • Replacement fittings
  • Flat-tip screw driver

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