No Go on First Morning start...

[olsan100]

Hey guys. I tried looking for this through search, but I didn't come up with anything.

Anyway.. It seems like every morning, the first try at starting gives me a rough idle for a few seconds, then it quits. But, on the second try it goes just fine.

It's annoying more then anything, but I assume there must be some issue. It starts fine the rest of the day after that.

Any thoughts?

[theonlyrealperson]

I'm new to BMW's, but that sounds to me like a fuel pressure problem or water vapor in the fuel system.

Pressure in the fuel line declines overnight, when you first start the car in the morning the electric fuel pump doesn't have time to get the pressure where it should be. On the second time the pump has enough time to put the proper amount of pressure in the system.

I'd check for pinhole leaks in the fuel line, and failing that I'd test the fuel pump.

[theonlyrealperson]

Sorry, I should add that one way to test this (to see if it is the fuel system, at least), in the morning, turn the car on enough to engage the electrical system, but not quite enough to engage the starter and let it sit for a minute or two. (Or, if you can actually hear the pump, until it shuts off)

If it starts immediately after that and doesn't idle rough or shut off, then you're at least 80% sure it's the fuel system.

[brosher]

My first thought is fuel pump as well. It takes a lot more fuel pressure to start a car than it does to run. You can try turning the key on for a few seconds to prime the system, then start the car.

[SnakeyesTx]

Fuel pump check valve. Same thing I wanna get. BMA sells it for 7 bucks plus shipping, but I'm having difficulty getting their searchable part number. What happens basically is the fuel in the feed line is draining back into the tank and the pump doesn't have sufficient time to build up pressure again on the first crank. That's my theory and I'm sticking to it! :D

I have the same problem... also if I drive it for a while and let it sit for more than an hour it'll do the same thing. For 7 bucks, you can't lose.

[brosher]

Did you ever find such a part? I can't find anything like that when looking on realoem for my 540i.

[saj3n]

Fuel pump check valve.

Same part available for the 530i's? I believe we have the same problem right SnakeyesTx?