Car shuts off when foot is not on gas

[nailtech33]

my BMW shus off when i have to stop. D you know why

[shorod]

Welcome to the forum!

Is it because you turn off the ignition?

Seriously, a bit more information would be helpful here. Is this an manual or automatic transmission? Does this only happen when the car is warmed up? Does it occur more when the car is cold? Only after it's been raining? Only if the A/C or defroster is turned on? Only after a trip on the highway, only after the first stop of the day, then it's fine? Does the car start back up just fine, or will it stall unless you put the car in neutral until you're ready to accelerate?

Also, you should consider searching the forum specific to your BMW for other instances of this issue. A search may review the 50 other owners of your model BMW have had to replace their Idle Air Control valve to solve similar issues. If your search of the BMW forum does not yield any results, be sure to provide specifics of your car (year, model, engine, transmission) as well as any of the details to some of the questions above. Have you tried checking the engine computer for codes? If yes, what codes were present?

-Rod

[HITKHILADI]

Hey I have a 2002 325XI Automatic. Recently my car shut down on the highway when I had just less than a 1/4 tank of gas. Usually it would go another 50 miles after the gas light comes up. My car takes about 16 gallons..and when I filled it up it only took about 13 gallons. My engine was warm & I had the heat on also. Please let me know whats causing these symptoms. Thank you.

[shorod]

Welcome to the forum! Once it stalls, does it start right back up? Does it stall randomly, or always when you are coming to a stop/accelerating from a stop/coasting? When was the battery last replaced? What have you checked? Does it idle smoothly? When was the last tune up performed?

-Rod

[HITKHILADI]

Once it stalls it comes to dead Stop slowly..then I tired to crank it several times it won't. I went and opened up the gas cap and it started back up. So I think its something to do with the Fuel System. When its filled up..its fine. It happens mostly when am accelerating on low fuel from a Stop/Coasting. The battery as never been replaced..Idling is smooth/normal. Changed all the belts recently..also the Thermostat. Haven't changed the spark plugs or other tune ups yet.

[MagicRat]

So, the problem only happens when the fuel level is getting pretty low, correct?
I think there is something wrong with the fuel pick-up tube or baffles (if any exist) inside the gas tank.
Any change in speed or cornering can cause the fuel to slosh around the gas tank when the level is low. Possibly the sloshing fuel is exposing the bottom of the pick up tube to air, which would cause you to lose fuel pressure and thus the engine would stop running.
When you stop and the fuel settles, the pick up tube is now covered and the problem goes away.

Frankly, I think the fuel pump/sending unit should be removed from the gas tank to inspect for damage.

Also, when the sender is out, look inside the gas tank for foreign objects. I once had some joker place a plastic bag inside my truck's gas tank, which created a fuel starvation problem which was hard to diagnose.

I don't know about your car, but my BMW had an access door to the sender unit in the trunk floor. It made servicing this item quite easy. Just be careful because obviously gasoline is very volatile.

[shorod]

I suspect a weak fuel pump. The fuel pump is surrounded in fuel when the tank is full, which helps keep the pump cool. When the level is low, the pump holds more heat and, if it's wearing out, that can cause inconsistent fuel pressure. I've heard of others testing fuel pump health by checking for easier starting by opening the fuel cap, but I'm not sure I understand why that helps. I suppose the pump doesn't have to work as hard to pick up fuel, it's not pulling a vacuum, but instead allowed air to easily replace the fuel it's trying to pump.

-Rod

[MagicRat]

Originally Posted by shorod

, the pump holds more heat.

Silly me, I dismissed that thought when thinking about this because I am freezing my automotive nay-nays off right now.

Of course this car is in West Palm Beach, so a heat problem is much more likely.