Dropping a cylinder when the car reaches 1/4 tank of gas

aj330ci · 03-01-2010, 01:53 PM

Ok, this is a really strange thing that has been happening to my car for the past few months, and just happened last night, so I'm kind of worried.

I drive a 2004 BMW M3.

When my car reaches right around 1/4 tank of gas left, it feels like the car drops a cylinder. Same feeling as like a coil pack going out. The car loses basically all acceleration, and if you try to get it moving, it just spits, sputters, and dies on you.

After I go to the gas station, fill the car up with gas, and let it run for a little while, it works just fine again. I did some reading on the Internet, and I know how the car is behaving is like a coil pack going out, but I doubt that's it since it only happens when the car reaches 1/4 tank of gas left.

I also know the gas gauge isn't wrong because when I stopped and filled it up, I put 12 gallons in on a 16 gallon tank, with the 4 gallons being the 1/4 tank that was left.

Does anybody have any ideas what could be going wrong with the car? The solution right now is to just keep it above 1/2 tank of gas at all times, but that's just until I can get it to the shop.

Thanks for any and all help!

Justin@SharkInjectorDirect · 03-01-2010, 02:13 PM

It sounds like it could be a failing fuel pump.

As the fuel level gets lower, it has to work harder to pump the fuel to the engine bay.

Think of it this way. Lets say you were on a 5 story building and there was a bucket of water on the ground level. Imagine trying to suck the water up to your level thru a straw. Now imagine the bucket of water was 6" below your mouth. Much less effort is needed.

ChasCan · 03-01-2010, 02:16 PM

Maybe something simpler? Fuel filter?

aj330ci · 03-01-2010, 02:22 PM

Quote:

Originally Posted by Justin@SharkInjectorDirect

It sounds like it could be a failing fuel pump.

As the fuel level gets lower, it has to work harder to pump the fuel to the engine bay.

Think of it this way. Lets say you were on a 5 story building and there was a bucket of water on the ground level. Imagine trying to suck the water up to your level thru a straw. Now imagine the bucket of water was 6" below your mouth. Much less effort is needed.

I was kind of thinking fuel pump as well. Guess all I can do is drive the 2 hours to the dealership, and let them take a look at it. Oh the joys of BMW maintenance, lol!

TKC · 03-01-2010, 02:24 PM

This might help you.

Good luck

http://forum.e46fanatics.com/showthr...highlight=fuel

aj330ci · 03-01-2010, 02:31 PM

Quote:

Originally Posted by TKC

This might help you.

Good luck

http://forum.e46fanatics.com/showthr...highlight=fuel

Wow AMAZING write-up! Thanks!

Justin@SharkInjectorDirect · 03-01-2010, 06:42 PM

Quote:

Originally Posted by ChasCan

Maybe something simpler? Fuel filter?

A fuel filter would most likely exibit issues all the time. It would not really be dependant on the fuel level.

But, it never hurts to change the fuel filter.

03-01-2010, 01:53 PM	#1
aj330ci Registered User Join Date: Apr 2006 Location: Willmar, MN Posts: 85 My Ride: 2004 BMW M3 View My Garage	Dropping a cylinder when the car reaches 1/4 tank of gas Ok, this is a really strange thing that has been happening to my car for the past few months, and just happened last night, so I'm kind of worried. I drive a 2004 BMW M3. When my car reaches right around 1/4 tank of gas left, it feels like the car drops a cylinder. Same feeling as like a coil pack going out. The car loses basically all acceleration, and if you try to get it moving, it just spits, sputters, and dies on you. After I go to the gas station, fill the car up with gas, and let it run for a little while, it works just fine again. I did some reading on the Internet, and I know how the car is behaving is like a coil pack going out, but I doubt that's it since it only happens when the car reaches 1/4 tank of gas left. I also know the gas gauge isn't wrong because when I stopped and filled it up, I put 12 gallons in on a 16 gallon tank, with the 4 gallons being the 1/4 tank that was left. Does anybody have any ideas what could be going wrong with the car? The solution right now is to just keep it above 1/2 tank of gas at all times, but that's just until I can get it to the shop. Thanks for any and all help! __________________ 2009 VW GTi 2004 BMW M3 Silver Gray - Dinan Stage II SOLD 2003 Silverstone Nissan 350Z SOLD 2003 BMW 330CI - Topaz Blue SOLD

03-01-2010, 02:24 PM	#5
TKC Registered User Join Date: Nov 2005 Location: San Jose, CA & Dallas, TX Posts: 20,197 My Ride: 330cic & R6 View My Garage	This might help you. Good luck http://forum.e46fanatics.com/showthr...highlight=fuel __________________ EUROPROJEKTZ - Director, NorCal Chapter

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03-01-2010, 02:13 PM	#2
Justin@SharkInjectorDirect Past Site Sponsor Join Date: Jan 2010 Location: Utah Posts: 114 My Ride: Many Cars View My Garage	It sounds like it could be a failing fuel pump. As the fuel level gets lower, it has to work harder to pump the fuel to the engine bay. Think of it this way. Lets say you were on a 5 story building and there was a bucket of water on the ground level. Imagine trying to suck the water up to your level thru a straw. Now imagine the bucket of water was 6" below your mouth. Much less effort is needed.

03-01-2010, 02:16 PM	#3
ChasCan Registered User Join Date: Jan 2010 Location: Connecticut Posts: 1,066 My Ride: 2001 330xi View My Garage	Maybe something simpler? Fuel filter?