1996 BMW 840 - How to remove old gas?

How do I get the old gasoline out of the tank that’s been sitting for over 2 years ?
I tried getting a hose down the spout where you put gas in but the hose won’t get in. It goes a couple inches and then it stops.

I am not sure about your car. but if it has a fuel filter you can disconnect it and hook up a hose to the side closest to the tank and run the other end of the hose to a gas can. then turn the key forward and let the fuel pump, pump it into the gas can.

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I can tell you how I got the old fuel out of a '97 328i.
I got an old round 12 volt plug from my junk drawer and crimped a couple of round crimp wire splices onto the ends of its wires.
Then I screwed the core out of the shrader valve on the fuel rail where you can check the fuel pressure. I slipped a hose over that schrader valve and ran it to a gas can.
Then I snapped up the back seat and removed the cover over the fuel pump (passenger side below seat). I unplugged the fuel pump and attached my 12 volt supply to the fuel pump power connections. It pumped most of the fuel from the tank.
My tank had two lobes, and it moves fuel from the driver side lobe to the passenger side where the fuel pump is located only when the engine is running, so when I just pumped the passenger side dry with the engine not running, I still had 3-4 gallons in the driver side lobe…

I take a the hose from my fuel pressure gage, hook Schrader end on the Schrader on the fuel rail and the other end to gas can. Jumper 30, 87 at fuel pump relay. Do not run dry for too long to protect pump. Do not jump relays if your not confident in your experience. Jumping wrong terminals can do damage at the speed of electricity.

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You could also have the car towed to a shop, and pay them to do it.

Remember, you can’t just pour old gas down the drain or out into the street. Or at least…you shouldn’t. A shop will have a way to get rid of old gas.

Plus you’ll get to sit in their air conditioned shop and drink their coffee. The older I get, the more that makes sense to me…

You do realize that when the key is turned on, the fuel pump only runs for a second or two and then shuts off?


yes. they would have to keep doing it. but its easier if someone doesnt know electrical stuff and start hooking up wires to keep the pump running. plus there is less of a chance of running the pump dry and burning it up.

I was working on my car and took a break to mow lawn. And realized I had no gas for mower. I did have a FP test kit and pumped 1/2 gal into can. I had no 2 sec issue to deal with. I think I just turned key to on. Don’t recall

I’ve always hooked up a hose from the test port fitting (Schrader valve removed) and used a jumper wire on the fuel pump relay. Extreme care must be used of course to make sure there are no sparks near gasoline vapors.

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you have to remember, most people looking for help might not have the automotive knowledge that most of you have. me included thats why they come here. and they probably dont have or even know of the tool to remove the schrader valve. I was just trying to make it easier for them.

That’s been the best way to drain the gas tank on a fuel injected vehicle.


Don’t. Add a bottle of propanol (Iso-Heet, for instance) to scavenge moisture and a bottle of gas cleaner to dissolve varnish then drive. Use another bottle of gas cleaner the next time you fill up.

Excellent point Warrior! Come to think of it, I used to get valve cover caps with schrader tools on them all the time. Other than the ones rolling around in the bottoms of my tool box drawers, I have not seen one of those in 40 years.

I wouldn’t do that…gas with Ethanol (which I’ll assume it is since most gas sold today is E10) gets really nasty between 8 months and 1 year…as in it turns into a nasty varnish that doesn’t ignite very well. If it’s been sitting for 2+ years like the OP said, I wouldn’t risk running that crap through my lines and injectors even with Iso-Heet and Techron.

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I’ve gone 2 years between buying gas.

so you have a tanker truck in your back yard, do you. LOL

and you have an old as dirt 87 Toyota pickup truck with a carburetor…I’d be more willing to risk running untreated 2+ year old gasoline in something like that than a newer car. Plus you pre-treat your gasoline with Iso-Heet anyway, right?

Running the fuel pump to pump it out works if you know how. If you don’t know how, you’ve never done anything like that before, suggest to hire a shop to do this for you. Besides the many safety issues, as mentioned above, you’re probably going to have to take the drained gasoline to a shop anyway for disposal. If you don’t know how to do the fuel pump method, and still insist on doing it yourself, there’s usually a flexible rubber hose between the fuel filler pipe and the tank. You might can get a siphon hose into the tank via that pathway. I’m not recommending that method btw, just saying. The reason you can’t get a siphon hose through the normal fill up hole is probably by design, to prevent gas thieves from siphoning your tank.

The engine compression is book value. It gets NHTSA mpg. It passes biennial emissions tests with values low enough for a new car (sometimes after I make repairs.)

When I re-built the carburetor a few years ago it showed no sign of varnish.

Annually, in years that I buy gas.