Budget M3

Warning: Not a Porsche story...purists may logoff now....european car enthusiasts, please read on and offer your expert opinions

So I filled up the 1985 M635 this morning and took her out with the local BMW CCA chapter for a nice drive and museum tour, followed by lunch....just under 100 miles roundtrip, mostly freeway. The weather today was HOT HOT HOT (106F / 41C) , and the 1980's air conditioning was barely up to the task. With all of the vents pointed at me alone in the car, the AC kept me cool enough so as to be moderately comfortable. The car's cooling system, however, was solid and the temp needle only barely moved past the halfway point on the entire trip.

Upon arriving back home I pulled into my driveway quite pleased with the way the old girl had performed on such a challenging hot day. I turned off the car and KA-BOOOOOOM! I immediately heard the dreaded sound of dripping fluid, so of course my first thought was that one of the cooling system hoses had let loose. After swearing at myself for being so foolish as to think a 27-year old car could be up to the challenge of extended driving on a Southern Arizona summer day, I got out of the car to inspect the damage. That's when I smelled gas....A LOT OF IT!

I went around to the rear of the car only to find the gas tank filler neck (with the gas cap intact) lying on the ground underneath the car. The gas filler flap that is normally closed is wide open, and the side of both my car and my garage are drenched with at least a gallon, if not two, of 91 octane. After running around like a mad man with a hose to rinse the car, house and driveway, I have a few minutes to think about what just happened. I am thankful that: 1) my wife was not with me—she would have been exiting the car on the side of the exploding gas tank and could have been seriously injured, 2) I parked in the driveway, not in the garage which would have created a huge mess and even more damage, and 3) my beloved Z1 was pushed far enough forward in the garage so as to escape the geyser of fuel that shot about 15 feet out the side of the 6'er.

I have never seen or heard of anything like this before, and am trying to figure out what in the world happened. My first thought of course is that the incident is heat-related,. however....Just last week I had all of the fuel hoses replaced. One of them was leaking, and since they are 27 years old, I wanted peace of mind so replaced them all at the same time. My usual independent mechanic whom I trust did the work. I had driven the car several times since the repair without incident, mostly short trips of less than 20 miles. Is it possible that they somehow closed off a vent somewhere in the process of replacing the fuel lines? My euro-spec car does not have a charcoal canister on the tank like US models do.....could that be a contributing factor? Could my fuel pump relay be the culprit (not shutting off the fuel pressure and somehow over-pressurizing the tank)? Were there likely any warning signs that I inadvertently ignored before the tank exploded?

The gas was cleaned up at this point, but here is the aftermath exactly as I found it...

fuel door w filler neck


filler door


filler neck w gas cap

Anyone ever seen or heard of something like this happening before?

s4treg

Probably better put as Holy sh$t!

I'm subscribed to this thread, definitely want to see/hear what caused this.

Budget M3

Having it towed to the shop tomorrow. Will let you know once we figure it out. Latest speculation as to possible causes:

1. bad vapor expansion tank or blocked tubing to expansion tank (and when the fuel lines were replaced, the excess pressure no longer was able to seep out through the old lines)
2. misrouted fuel lines when they were replaced (unlikely, but possible)
3. poor installation of original fuel filler neck when the car was federalized for import

Stay tuned...

dcrasta

Bad or removed Fuel Evaporator system.

This is supposed to regulate the flow of air into the fuel tank and allow for the recovery of gasoline vapors, however a lot of people remove these Emissions controls.

http://forums.pelicanparts.com/101-p...ol-system.html

Whiplash_89

Pretty crazy.

Budget M3

Seems very possible in this case, but can't imagine why in the world woudl someone remove it?

Budget M3

Car went back to the shop and is still undergoing troubleshooting. It is clearly something with the venting system. They owe me a call tomorrow with the "official diagnosis".

s4treg

still subscribed.