Won’t start

[Sruiz25]

I own a 1988 325 and while I was driving the car just turned off and now it won’t start, I can hear spinning.

[my1stE30]

many possibilities, but the first two that come to mind are a failed fuel pump or a failed Crankshaft Position Sensor (CPS) ....

... if a failed CPS then you will have no spark and no power to the fuel pump when the engine is cranking. This is an electrical issue so when the CPS fails while driving the tach will drop suddenly to zero even when the car is coasting to a stop

... if a failed fuel pump then there may be still some fuel pressure but the pressure would have dropped below some threshold value to properly operate the injectors and the tach would continue to read the rpm and only slowly decrease as the car coasted to a stop

so... check for spark and if you can measure the fuel pressure when the engine is cranking

both of these issues are common for the 30 yr old E30s

[323i E30]

^ With a failed crank sensor you will see no movement of the tach needle while trying to start. That's a nice check.

A broken timng belt will also immediately kill the engine of course. Take off the oilcap and look inside while someone else is trying to start the car.
When you see no movement in there you have a problem.