wife ran out of gas on interstate.... - United Bimmer Community

**bcaughhorn** · 02-17-2012, 10:56 PM

my wife called me and told me she was sitting on the side of the interstate. the car said it had 51 miles left but acted like it was out of gas. so i went and put a couple gallons in and sure enough it fired rite up.

what will cause the computer to be off like this? the needle was on 1/8. i have ran it down around 8 miles left a few months ago so this is something new. anybody have any ideas on it????

DEATH2000 · 02-18-2012, 10:13 AM

Possibly something with the fuel pump or a sensor in their. If it failed it may have said you had more gas then you thought.

**Manolito** · 02-19-2012, 11:30 PM

The problem is the fuel transfer pump. The fuel tank has two sides, but the fuel pump picks up only from the passenger (US) side of the tank, so if the fuel does not transfer over to that side, you run out of fuel before the tank registers empty. When you add even a little fuel, you are adding it to the side where the main pump is, so the car starts.

On an e36, I understand that the fuel transfer pump is a jet pump that uses the fuel coming back from the fuel rail as its power source. On an e46, it looks to me like there is no fuel coming back from the fuel rail (it comes back only as far as the fuel filter) so I don't know what powers the transfer pump.

My boss's '03 lost its transfer pump while his wife was driving. He had it fixed at the dealer so I never got to see the details.