The 97-99 A8 is prone to two types of fuel leaks, one coming from the high pressure fuel line under the hood, and the other at the gas tank sending unit seal in the trunk. This procedure covers the high pressure fuel line under the hood. It is normally noticed during the cold winter months. The fitting leaks when very cold and fuel leaks out. It creates a smell of fuel in the passenger compartment. Once the fuel line heats up a small amount (such as after the car is turned off in the winter and the engine heat causes it to increase in temperature), it usually seals up.
Fuel leaks and lines are serious business. This procedure is for a repair of the line versus replacement of the entire fuel line system. The fuel lines (which are all together as a kit) from the dealer is about $800 for the parts. Then it has to be installed from the engine compartment back to the fuel tank. This procedure repairs the leak, costs about $10.00 and takes about an hour.
Audipages.com takes no responsibility for this repair! Use it at your own risk.
- 17 mm open ended wrench
- 14 mm open ended wrench
- Accetone or equivalent
- 80 grit sandpaper
- Fuel resistant epoxy kit
Supplies required for repair. Make sure that the epoxy kit is fuel resistant.
The fuel hose leaks on the high pressure side at one of the fittings. The fuel hoses are sold as one piece from the dealer, which include the supply, return and one other hose attached. It is a one piece kit that runs from the engine to the gas tank.
High pressure fuel line leak location. When it leaks, it just drips out. The fitting breaks down the pressure, so the leak is actually very low pressure.
Fuel line components.
Remove the low pressure fuel line from the fuel regulator. This is required to get proper access to the high pressure line.
Relieve the residual fuel pressure in the fuel line by cracking the high pressure line fittings. This is accomplished by using the 17 and 14 mm wrenches. Place a paper towel under the fuel line to capture the fuel that will drip.
Remove low pressure line, relieve high pressure line fuel pressure.
Remove the high pressure line, and clean with accetone. Using the 80 grit sandpaper, prep the surface by scuffing it with the sandpaper. Scuff the pipe and the fuel line fitting. After scuffing is complete, clean thoroughly with accetone.
Loosely attach the high pressure fuel line. Ensure that the angle on the line is correct for the engine plastic cover and that the low pressure line will not interfere.
Using the epoxy, place it on the fuel line. Perform this step in accordance with the instructions on the epoxy package. Let it cure in accordance with the instructions, preferably overnight. After the epoxy is cured, tighten the high pressure fittings and reinstall the low pressure line. Start the car and ensure there are no leaks. Reinstall engine plastic covers.