DIY - Lowering fuel pressure - B5/6/7, C5, and basically all other Audis

DIY/TECH/INFORMATIVE
#1

Why: This is a good safety step for working on fuel systems. Nobody like having gas go all over the place and there is of course the risk of fire.

Tools required:
Car key
Fuse puller (should be attached to the inside of the side dash board trim cover) or you can use needle nose pliers

Steps:
1. Open driver’s door all the way
2. Look at the left side of the dash that would be covered by the driver’s door. There is a big trim cover (half heart shaped) that has a notch where it meets the dash board.
3. Use the metal shank portion of the car key to pop the panel off the side of the dash by using that notch in the cover.


http://i284.photobucket.com/albums/ll37/Jimmybones777/20140902_153740_zps10510d9a.jpg

  1. Remove the little white fuse puller from the inside of the trim panel that goes on the side of the dash board.
  2. Use the fuse puller to remove the fuel pump fuse. Usually it is fuse #28 on most cars. Which is located on the very back row and three spots up from the bottom. The B8 and newer cars have the fuse in a different location but this procedure is basically the same otherwise.


http://i284.photobucket.com/albums/ll37/Jimmybones777/20140902_153817_zpseb6f33b6.jpg

  1. Try starting the engine. Some cars will only crank like most B5/C5s. Other cars will start and then die like most B6s. Most of the cars with FSI engines will start up and run so you need to press on the gas pedal until the engine dies. Once the engine dies try cranking it two to three more times just to be sure.

  2. Once you are done with other repairs and are ready to start the engine go ahead and put the fuel pump fuse back in. I like to cycle the key a few times so that the lights come on the dash but the engine does not crank so that the fuel pump can build up fuel pressure to the engine.

#2

Great post Jimmy. Something to add. When looking to start the car again. Make sure the battery is unplugged. Unplugging the battery resets the fuel pump prime cycles. What I do is I unplug the battery. Put the fuse back in shut the driver side door (important step) and then plug back in the battery. Now when you open the door the fuel pump will prime the fuel system. Since you drained the system lines it wont quite be enough. So get into the car shut the door (important step) and then turn the key to accessory without trying to start the car. Then turn the key off and remove the key. With the key removed open the driver door shut and open the door again. This will help cycle the pump two more times. Now when you turn the key to start it you should be good. The only last bit I do is. I turn the key forward for about 45 seconds anytime I have the battery disconnected. Turning the key forward but not starting the car will let the throttle body go through its adaption cycle.

#3

X2 Jimmy. Stuff like this is “common knowledge” to the old experienced techs, but is all too often overlooked by the DIY’er or home mechanic. Stuff like this is very valuable to the online community and it’s nice to have it clearly explained.