Chevrolet Repair: fuel, steel line, pulsator

Question
ive got a 92 chev k2500, 5.7 throttle body f/i. cranks but no start. i wanted to verify if i was getting fuel, so i disconnected the return fuel line first(just because i wasn't sure which was which) and cranked it over. it sputtered to my surprise and acted like it was going to start. so i tightened the line and after a few seconds it started. i let i run for a min, sprayed some cleaner in in the t/b. then shut it down to see if it would start. cranks but no start again. then i loosened the fuel pressure line and cranked it and verified that i do pump fuel during cranking. i repeated the return line procedure that worked in the first place. cranks but no start. im wondering if i have an air lock issue in the tank or a leak in the in tank pump that's sucking air? not sure what it is. if you could help that would be great. need to get to work!!

Answer
Actually Don, GM had a TSB posted on the fuel pump pulsator (in tank)on those trucks. It is the rubber or plastic line going from your pump to the steel line inside the fuel tank. They get cracked and leak causing a lack of or poor fuel pressure, which in turn causes a hard or no start condition. an easier check than dropping the fuel tank is to check fuel pressure (9-13 psi key on engine off). Unfortunately gm never installed a test port on these engines and you'll have to get a gauge that goes between the fuel line and the engine where you disconnected it. I hope this is some help to you.