Car won’t start all of a sudden

[hp13]

I took my battery out of my E30 last night to charge up the battery and I went to throw it in my car to try starting it up and it started up perfectly fine as usual. I took the battery back out and left the car for a few hours and came back to start up the car and check on things. I put the same battery back in and the car won't start now. It cranks perfectly fine the battery is fully charged but there's no sputtering or anything, the car does not even try to start. I jumped the fuel pump relay and there's fuel. I also pulled out a spark plug and it smelled like gas which I assume is normal considering I was cranking it for a while. It is fairly cold outside but I don't understand how it went from starting properly to no sign of starting after taking the battery out and putting it back in. Any suggestions on what to check or test out are appreciated!

I have an M30 swap if that helps

[twright]

Sometimes if you only let the car run for a few seconds and then shut it off, it won't like that. Let is sit overnight and try it again.

[Panici]

Sometimes if you only let the car run for a few seconds and then shut it off, it won't like that. Let is sit overnight and try it again.

Just to elaborate on this:
Car is getting full cold start enrichment, and it's flooding when shut off right away.

If you pull the plugs and crank a bit it should help to dry things out. (Might be prudent to disable the coil so you're not throwing sparks at the same time)

Gas on the plugs should also evaporate away when they're on the bench.

My E36 will missfire on a cyl or two on restart if I have just fired it up to move in the driveway without letting it warm up at all.
It's a more modern platform so ECU should have tighter control of the fueling and not be starting pig rich like something older. I suspect weak coil packs or subpar enrichment tables on the RKtunes ECU (which came with the car).

[ForcedFirebird]

Not sure if you are running the late Motronic, if so, the blue coolant temp sensor dictates warm up enrichment. Same with the TPS idle setting. If both of those are malfunctioning simultaneously, the flooding is amplified. If you are using early model, the sensor is white. I know the blue temp off the top of my head, only because I just checked one at work, should be 300-320ohm at operating temp.

As mentioned, let the car sit, or clean/replace plugs. If you are stranded in this situation, often times you cam put the accelerator to the floor while cranking and it will clear out - might have to hold the key in start longer than you feel comfortable with, but usually, it eventually starts.

[hopeful]

Try jumping the battery post to the additional small wire, sounds like your fusible link might have blown... Search fusible link you might find it useful.