turn over but ,won't crank up on 1998 BMW 328is

put another engien in it ,drove it for about a week ,now it turn over but won't crank up.what can cause this to happen?

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1 answer
Many, many things i.e fuel pump, crank sensor, out of gas etc, etc.
Really need to have the car diagnosed properly.

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https://repairpal.com/directory?address=35456&car_brand_names=BMW