cylinder 5 misfire, heavy white smoke

[lightning666]

DTC is telling me cylinder 5 misfire, and i accidently deleted another code, but it would idle for a bit and was just blowing white smoke non stop at idle. BUt now it wont start. Any ideas whats wrong, truck is stranded, gotta get it running.

[lightning666]

just drained the water seperator and some really nasty stuff came out of there, looked like rusty water. I had also just filled up the tank, truck had been parked for 4 days, and only drove like 2 miles and this started happening.

[firefighter317]

ive seen on some with metal tanks, the inside of the fuel tank rusts out and the rust gets up and clogs the pickup screen on the fuel pump.