Fabrik8

My BMW-specific knowledge is really limited, so I need help on this one.

I haven't actually been out to look at the car yet, but I want to be armed with enough info to check the likely suspects first. Car belongs to a friend who just bought it and doesn't know much about BMWs yet.


Car was run out of gas about a week ago, because the gauge isn't apparently that accurate at the low end of the scale (or maybe it is, and most other cars aren't?). Filled the car up, let the pump prime, and it started back up after a few tries. Told my friend to change the fuel filter, hasn't had a chance in the last 6 days. No problems until today.

Today, car was stumbling and then shut off. Cranks fine, won't run. I had my friend take off the rear seat bottom to hear if the fuel pump is priming, but it's either not priming or it's too quiet to hear easily with the surrounding noise.

Like I said, I haven't attacked it with my ninja tools yet, so I don't know if the pump is getting power.



So, anyone have any intuition about what it might be? Any typical BMW-specific failure points that I should research and check? I'm going to need to hit the big things in a gas station parking lot, so my access to lots of things might be limited.

Halfrican

BUT BUT BUT!

You're like House?! You're sposed to know everythings!??!?!

blah

The good news is that the 2.5L in there is pretty much the same 2.5L that BMW came out with in the late 80's. There's no high tech bullshittery, it's just a normal engine.

Is the check engine light on? If so, was on before this incident? The only kinda weird thing is that there's a fuel tank breather valve located in the engine compartment and they have a tendency to do whatever they want (including taking a crap) at any time. It'll set off the CEL and it's about $70 for a new one.

But outside of the feul pump taking a crap, I got nothing. Like I said, it's a pretty basic engine setup and I'm sure you'll be able to track down anything wrong pretty quickly.

Fabrik8

No CELs, no nothing. I called around looking for a fuel pump (just to be prepared), and one of the dealerships said the pumps don't like to be run out of gas. So that's a clue. Anyway, in a few hours I'll go check it out.

Cobra4B

I mean most fuel pumps are cooled by being submersed in fuel and having fuel flow through them... running them really low or out of gas is akin to running your engine w/o coolant in it for a bit.... no?

marlinspike

A superior Mercedes fuel pump is designed as an external pump. Not only does it not hurt them to run dry, but it also allows them to get every last drop out of the tank.
Just saying.
But yeah, in-tank pumps generally rely on being in fuel for cooling. The BMW manuals actually point this out.

BAN HAMMER

this thread isnt real.

Trunk Impaired

Tell your friend welcome to the joys of BMW ownership (my sunroof got stuck in the fully open position last night) just take it to the dealership and put his ass out for a pounding when the bill comes back. It's the BMW way. Other than that I'd say read the factory or bentley manual on the car (it's sometimes helpful in diagnosing issues) but yes, running a BMW (or just about any car) completely dry is not good at all. Fuel pump is most likely the culprit, it's the only thing that really makes sense.

the law

Have you checked the Fuel pump relay? Use a jumper wire from pin 30 to 87, that should tell you if the relay is bad or not because that will give you power to your fuel pump. That way you can crank it and drive it home. If that's not the case then check the DME relay. I'm currently going through a similar situation but with a little twist. Let me know if that doesn't help, I can at least guide you in the right direction if I don't have a solution.

the law

Ohh I read it wrong, it might not be pin 30 and 87, I know it is for e36's but I'm pretty sure it'll do the same thing.