92 Would not start. Help

Ok, I have been fighting this problem for the past 3 weeks. On start up it does not want to start or will not start. It turns over great. Checked fuel pressure and was below 20psi. So I replace the Fuel filter, Fuel pump, Also replace TPS, Spark plugs, and wires. This morning when out to go to work. and it turn over but would not start. push on the valve on the fuel rail and got very little fuel out of it(just like before I put the new fuel filter and pump in). What am I missing? If it starts it runs great. But today I just could not get it to start.

Also it seems like the longer it sets the worse it is to start.
Any help would be great!

Thanks for looking.

92 4.0L auto. 197,345

The fuel pump check valve must be leaking, causing fuel pressure to bleed off back into the tank.

How would I go about checking that, and where is it?

thanks for the reply.

i've been having a similar problem..cranks over but won't start, a couple of times itwouldn't crank either....but wiggling the steering column and it starts...so i'm suspecting the ignition switch is going bad...