chevy gear heads

Checked for spark , spark coming off coil wire, then checked spark plug wire, pulled spark plug wire off at distributor spark came out of distributor cap to spark plug wire. So appears to be getting spark. Next, I took off fuel filter under vehicle, turned over engine didn't appear to be pumping fuel out of open line. Fuel filter was changed last season didn't appear to be clogged up and I could blow thru it freely, reinstalled filter.When engine start it runs good, you just do not know if it is going to start or not. Today I started it up ,it fired right off and ran. after about a minute I turned engine off tried to restart and all it did was turn over, have tried it several times today it will l not start. By the way Coil is external.