Purchased 1991 Z-28 No motor + trans that owner switched to carb. + installed inline pump,i installed new drivetrain + runs perfect then i parked the car for a few months + car will not start + out of gas because pumps work for 5 seconds when security light is on then quits when light goes out,so disconnect inline pump and run fuel line to gas can + rewire that pump to fan + it runs perfect like before but the in tank pump only gets power when the security light is on so is this a coincident because when i hook all fuel lines back on inline pump cannot pump fuel from tank thru intank pump that shuts off in 5 seconds but i never had this problem driving it before

 

Oil pressure switch. If you don't generate any oil pressure in the first few seconds of cranking, or if the switch is bad, ( seems more likely for your description ) then the fuel relay circuit stops sending power to the pump.

 

i ran separate power to the intank pump + had separate to inline pump,car ran fine until carb ran out of fuel,does anyone know if you can suck thru intank pump if its not working