The car turns over, tries to catch, but won’t start. No codes are stored or given, and the battery is brand-new. The car has not been driven in two months, but is well maintained and stored in our garage. Any thoughts on what the problem could be?
First find out if it is spark of fuel - that cuts the problem in half.
Fuel: shoot some starter fluid into the intake - if it fires up even briefly then the problem is fuel. (You can actually start by listening for the hum of the fuel pump when you turn the key - last position before crank).
Spark: a spare spark plug or spark tester can be used to check for spark.
If you have a way to get there, stop at an auto parts store - you can get both starter fluid & a spark tester there.
Once you know which, you can report back.
If you can hear the fuel pump spin up for a second after you turn the key to the on position, the next suspect would be the crank position sensor. I don’t know where they put it on the e46, but on the previous model it was on the front of the engine near the air conditioning compressor, as I recall. Access from beneath. Tough to get hold of, very tight clearances in there. If you can get to its lead, unplug it and make sure it is not corroded. That is a very weak signal, so a tiny bit of corrosion will stop you.
That’s a great lead…the fuel pump does spin up, so that might be it. Other than checking for corrosion, is there a way to test it conclusively?
Don’t know, but this reminds me that I need to buy the Bentley manual for my wife’s 330 before I need it. Her car has been so trouble-free for 70k miles, I have never been motivated to spend the money.