I have a 1985 Nissan pickup with a z24 engine that isn't firing on the exhaust side. Any ideas?

check wiring.

I already checked the wiring and everything was okay. Fire going to the distributor but not coming out. No fire coming out of the plug wires.

here try this and let me know what you've found. mws919
Disconnect a clutch switch harness connector.
Disconnect a vacuum hose from vacuum switch and connect a proper vacuum hose and suitable vacuum source to vacuum switch.
Connect timing light to the exhaust side of high tension cable.
Apply vacuum of 5.91 inches Hg to vacuum switch and start engine.
Reduce vacuum gradually and check that timing light does not brighten and dim when vacuum reaches approximately 3.15 inches Hg. If it does, check individual components and replace as necessary.
Connect timing light to intake side of high tension cable and apply vacuum of 5.91 inches Hg to vacuum switch.
Reduce vacuum gradually and check that spark timing advances. If not, replace IC unit in distributor.