bmw 2002

Gas Tank Replacement/Refurb

Mar 23, 2008

     After one very nice start, Webby has since refused to fire up.  I checked the timing, the plugs, the engine's compression, and the carb is brand new.  It should work.  Fuel, compression, and spark:  that's all you need to get an engine to start, right?  Compression and spark are fine, and I thought that the fuel was, too.  Not so.  The gas tank smelled like turpentine and there was no movement of fuel through the clear plastic fuel filter.

     Sitting under the Arizona sun for three years, Webby's gas tank went dry.  When I refilled it with gasoline, the crud inside dissolved and clogged up the system.  The engine fired up the first time because it took a while for the crud to dissolve.  But sloshing around on a cross-country shipment and months of sitting were enough for that new gas to mix with the old crud and turn into something completely different.  I decided to swap out the gas tank with one not full of mystery material.

Draining the gas tank.  The siphon worked fairly well, though I did have to help it out using the "suck and spit" method (um, that didn't come out right).  There was a good five gallons in the tank . . . and gasoline isn't brown.

emptying gas tank

I pulled the tank and you can see the original malaga paint color underneath where it sat.

gas tank removed

Peering into the old gas tank you can see the residue of the gas that evaporated.

inside gas tank

Here's a close-up of where the tank sat.  You can see the original gasket between the body and the tank and why this is a common spot for water to collect and form rust.

gas tank gasket

On the right is the sender unit from Webby's gas tank, sitting next to the hole in the tank that it used to fill.  On the left, a sender from a tank that wasn't left to dry out when full of gas.  The residue is tacky like tar and can be scraped off.

nasty sender unit

I cleaned off the dirt and old gasket material then masked, primed, and painted the area where the gas tank rests.  I did this to give a better surface for the new seal around the tank.  It's the shiniest part of the car and it's about to get covered up!

gas tank surround painted

I used closed-cell foam as a seal between the body and tank.  It won't hold water and the adhesive on each side will give a good seal.  Not shown, on the right I put another line of gasket closer to the hole in the body, giving a better seal than stock.

ball joint removed

A fresh tank sourced.  I cleaned it off and ground off as much gunk as I could using a wire toothed brush.  Here it is being primed before painting.

new gas tank primed

The "new" tank actually comes from a late-model '02.  To my knowledge, the only difference between early and late model gas tanks is the length of the filler tube.  So I used a hacksaw to shorten the filler tube to match Webby's rubber spout (which attaches the tank's filler tube to the car — what you put the pump into at the gas station).

filler tube shortened

After cutting the filler tube, the tank fits well using Webby's rubber spout.  All that's left is to replace a few short lengths of fuel line, then hopefully fresh fuel will be flowing and the engine will fire up nicely.

 Yeah, we'll see about that!  Such luck would not be in keeping with this restoration's theme.