On Draining the Gas Tanks

Assuming we're talking about the SI/II/III XJ6 here, there is a way to drain the fuel tanks. I wrote about this to David Brown just the other day.

At the bottom of the rear wing, a few inches behind the rear wheel well, you'll find a round plastic plug about 1.5" or 2" in diameter. This conceals the sump plug on the tank. To get that plug out you'll need to loosen a few of the screws that secure the bottom of the rear wing. Start with the ones closest to the plastic plug, and loosen them till you can push that plug upwards and to one side. Those screws are real tough - they're the anti-backout kind and they're not going to be happy about moving. You'll need the right size of screwdriver too - #3 or 4 I believe.

Open the fuel filler cap to release any built-up pressure. Once you get the plug moved aside, you'll see the tank sump plug beneath some foam padding. Loosen it and watch the yucky gas run out. The same is true on both sides.

BE SURE TO DO THIS OUTSIDE, AWAY FROM THE HOUSE.

You might want to get new seals before you start - no sense starting a leak problem.

Best of luck.

Absolutely do get the new seals ahead of time. On my car, the bottom of the right side tank was badly rusted and the turning force required to remove the plug caused the seam to split and a large leak to start. Ultimately this required replacing the tank which is a fairly big project and not cheap.

If you do get the plug out, it is a good idea to run a couple gallons of sacrificial gas through the tank to flush out some of the sludge in the bottom.

I will have to think some more to jog my memory, but off the top of my head, I will share what little I know.

The hardest part of the fuel tank removal is getting the filler necks off, usually they are "bound" up pretty good do to corrosion, and this tends to make removal a pain. The neck O.D. mates to the tanks I.D. and is sealed with an o-ring. I just busted my tanks loose per the manual, and let the weight of the tank be supported by the neck, then I started working the neck back and forth until it came loose, (make sure there is something under the fuel tank to absorb any sudden movement) I would not advise this method, if your paint was good, as it can scratch the filler neck wells, and due to water entrapment, this area needs all the paint it can get. If you are very adept at prying, it is also possible to alternate between the twisting motion and prying up against the neck, (with something narrow enough to fit as needed on the body, to pry against.

My car is a series 1, so yours should be a little less entrenched. I can't help you on the trim, as the filler assembly is one piece on a S1.

Basic overview, as it applied to my car. Remove rear bumper, check for wiring to disconnect. Pull the interior trim panels on both sides of the boot, and its best to remove the bottom trim, and interior trunk floor. Remove screws holding lower quarter panel on, and panel itself. Drain fuel. Disconnect qty. sending unit wires, and any and all lines, vent & fuel. At this point there should just be the main threaded rod and three (maybe four) bolts supporting the tank to the body, and of course the bloody filler neck. I removed the roll pin holding the fuel cap on, so as to have more room, and of course the retaining screws.

I would look closely at the interior and exterior of your tanks for rust, especially the tops. It is also a good time to replace any old vent lines, especially if your car has the "anti-siphon" lines in the C-pillar. There are flex lines that connect the tanks to the hard lines, it can cause a fuel smell in the interior. I would look at your qty. sending units also, but normally these can be accessed from the wheel wells. And you are fortunate, in that they are inexpensive for your S3.

You may want to start researching your parts order, as if you replace all the seals, etc. there is more nick nacks then you would expect. My thinking would be to have the lower qtr valences painted off the car, and clean up the interior of the qtr pnl well your in there, and throw some primer on it. Of course this is all based on my car, which after 25yrs had some surface rust in the area. The water drains tend to get pluged, I put low psi air on mine, and all sorts of critters where relocated to the far corner of the garage.

If you find any chunks of metal shaped like hershey's kisses, let me know what they are? I found six in my two tanks. I have been informed they may be part of the anti-siphon system, but I don't really need to know if this is true or not, as I am gutting out my entire fuel system, and modifying it.

Well I hope this helps, I am sure I have left something out, and your model may very well be different then mine. I enjoyed most of the process, with the exception of the two gallons of very old stinky fuel that came out at the most unfortunate time, It is a fairly rewarding job when your done though.