Assuming the guy that said no spark was correct, that would be your issue. Why no spark, you need to diagnose. Crank Position sensor going bad would cause a no-spark situation. So would a bad coil.
You can check the fuel pressure easily enough via the schrader valve behind the throttle body.
You can have a buddy turn the key from OFF to RUN (not crank), and put your finger on the Auto Shut-down Relay (ASD). In run, it should click on for about 2 seconds, then click off. In crank it should click on and stay on but you won't be able to tell because the engine is rocking. FYI, Auto Shutdown supplies power to the fuel pump and the coil.
It's not easy to test the coil or crank sensor. You need special tools, like noid lights and digital multimeters. Do you have these tools?
'91 Frankenheep YJ. 4.0, 4" BDS, Richmond 8.8, Titan 12k, 35" KM2's, rust.
'88 YJ, 4.2/4.0 head, +4½" & shackles, BFG 33's (sold)