92 Lumina Cranks But Wont Start

I have a 92 Lumina 3.1 L. It occassionally won't start at random times of the day. And on other day's theres no problem at all. It will Crank But Wont Start, sometimes it starts 5 minutes later but sometimes it can be Hour's.
When it first started 2 month's ago it happened a few times and wouldnt start at all. we could get it started buy hitting the fuel tank with a mallet but then that didnt work and we got the fuel pump replaced.The mechanic that did it told me that after he replaced the fuel pump it still didnt start but he said he checked all fuses(even the ones in by the engine) and he said he tried again and it started.So we brought it home and its been a month and most of the time it starts but about 1-2 times a week it doesnt. Mostly after getting gas for some reason .So I dont know whats going on and I hoped somebody could give me some advice. Thanks

try spraying some starter spra down the Throttle body while crranking it see if it start with that

when you do get it started how does it run? rough at all?

It started last night finally at 5 p.m and it ran fine. And it started this morning and its still running fine it just randomly wont start. Could it be the ignition module going bad. But to answer your questions when it does start it always runs normal.

Both the ignition module and crank sensor will cause intermittent random non-starts, as well as a bad ECM and fuel pressure regulator. Is the check engine light on? If so, pull the codes and post them here. If not, you need to check to see if you're getting spark when it doesn't start. If not, take the cover off and "tap test" the ECM (its under the hood, in the passenger side fenderwell). IF tapping on the ECM gets the car to start, you need an ECM. If tapping the ECM doesn't change anything, either the crank sensor or Ign module are bad. IF you're getting spark, my guess would be a fuel pressure regulator going bad, as you say you already replaced the fuel pump. A new part doesn't eliminate the fuel pump, as new parts fail too, but it reduces the likelyhood.