Failure to start/ beckfir from center of the car.

[Thornhill]

Hello everyone,
I'm new to this forum and this is my first post.  I've had my 318is for 10 years now, purchased from the original owner and always taken care of, yet she's getting older approaching 165K miles.

I have been planning a complete vacuum line overhaul for sometime now, and have finally found the time to do so. The last couple seasons, in weather below freezing, the car has struggled to start for me (once it has and is warmed up, she still runs like a raped ape). I attributed the starting problem to cracks in vacuum lines.

Well i tried to start it the other day, and the sound changed from the typical startup sound (the a da da da da vroom) to more of a vacuum cleaning sound (vra vra vra vra). Frankly, the sound seem to be coming from the underside of the car at the midpoint of the wheelbase.

Initially I thought I had flooded her in attempting to start her, so I took the plugs out and let her air out for a couple days. Just now, after installing the plugs and giving her a little shot of starting fluid in the intake, the car continued with the same recent noise when attempting to start, only this time it seemed like a mini backfire occured at the same underside position of the car mentioned earlier.

Any thoughts to what this could be and how to solve it? I hope I can solve this myself, because I always take it personally when I have to have a car towed due to my inability to fix it.

Thanks in advance for your suggestions.

RT

[Thornhill]

Oops, that title should read 'backfire'.