Fuel Line Leak Repair
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.
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.
Supplies and Tools Required
- 17 mm open ended wrench
- 14 mm open ended wrench
- Cutting tool for fuel line connections
- 5/16" fuel line suitable for fuel injection systems (4 feet will do both supply and return line)
- 2 hose clamps per line
Procedure
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.
Removal
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Remove the low pressure fuel line from the fuel regulator. This is required to get proper access to the high pressure line.
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Place a paper towel under the fuel line to capture the fuel that will drip.
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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.
Remove low pressure line, relieve high pressure line fuel pressure.
- Remove the high pressure line
Assembly
- Using a saw or other device, cut the fuel line fitting. Cut almost all the way through it and then use a pair of pliers to tear it apart. If you do the fender side first, you can then take it to your work bench and remove the fuel rail side next in a vice or other device.
- Cut the new 5/16" fuel hose to length
- Put a hose clamp on each end, and slide it over the barb fittings.
- Secure the hose clamp (make sure it's tight).
- Reassemble everything and you are done!
Source: www.audipages.com
Author: Paul Waterloo