Rogviler

You can drain it just by disconnecting the fuel pump. You may have to jack up the right side of the car to get it all out. Once you get all the hoses off and the couple of bolts on the side it should come right out. The hoses on the bottom are accessible from the outside. Don't forget to take the filler cap off and take off the boot thing. You won't have to take the seat out unless you're running new wires for the pump.

-Rog

Audiutah

Tried to drain the gas tank. When i pulled the pump, the inlet side had what i would describe as black silicone and the tube from the tank would not flow. Got the tank pulled though and drained it through the filler neck. Stinky stinky. Its permeating from the garage into the house. Tomorrow i will pull the filter and accumulator and see if i can push some air through the lines. No pics as none of this work is sexy. Will be buying a fuel distributor and other fuel related bits from Chris on this forum. I should have more progress and updates in the next week or two.

Rogviler

Oh man, sounds like some solid old fuel gunk? It's definitely a good thing pulling that tank.

-Rog

Audiutah

UGGHHH, there is an 1/8" layer of tar sludge at the bottom of the tank. I snaked some 12 gauge wires up the drain to break it up but still no drain. Isnt there a bladder type screen at the bottom of the tank ? I have it soaking in fresh gas but wondering if it will even break it down. Any one brought a tank like this back to life ? or is it done ?

TEF1701

Yes there is a fine mesh screen connected to the main outlet tube. Check out the end of this thread.

https://www.audiworld.com/forums/audi-4000-coupe-gt-discussion-29/ignition-timing-all-screwed-up-2832269/

Rog steered me towards toilet bowl cleaner. The pictures speak for themselves. Buy the jumbo two pack of The Works from Wal-Mart. Plug all of the outlets, dump both bottles in with a three foot length of chain, and swish it around every 20-30 minutes for about two hours. Once you rinse it out with water, immediately fog the tank with WD40. Otherwise the tank will flash rust pretty quickly.

I had issues with sludge clogging the screen at the bottom of the tank. When the tank was full, it diluted it enough for the car to run. Once it got below 1/4 tank, it would clog the screen again. I was amazed at the results.

Audiutah

Made some progress over the last 2 weeks. Got the tank pulled and tried the toilet bowl cleaner and 5ft. of chain inside. Cleaner didnt really break down the tar sludge. Put 96 oz of Carb cleaner inside. Will see tonight if it is working. If not there is a radiator shop that will boil it and reseal for 170.00. Hoping i wont have to spend and go that route. Removed the pre filter, regular filter and accumulator. Pre filter is completely gummed up. Is there an aftermarket replacement i can get from a parts store ?? The regular filter and accumulator were clean. I blew the supply and return lines out and they are also clean. Found out my trunk light was staying on and draining the battery. I have no top cluster lights. Pulled two bulbs and they werent burnt out. Hoping i can troubleshoot that. Dimmer and headlight switch both work. Oh and i also got the fuel float ungummed and will have a working gas gauge. Chris Youngren is selling me the CIS parts that will hopefully get it running. Hes out of town till Nov 5th so i have to wait.

TEF1701

Holy crap! That's some thick crud if the toilet cleaner didn't touch it. Rog warned me of tank sealants, and I tend to agree. The research I've done has been very hit or miss. Sealants either work really well or not well at all.

Audiutah

Im closer to having all the gunk out of the tank. I dont plan on sealing the tank cause i would end up sealing the sock filter at the bottom of the tank. Any other suggestions beyond fogging the tank so it doesn't flash rust ? Or will a little surface rust not be a big deal considering there are 3 filters inline prior to arriving at the Distributor.