2001 Chevy blazer Xtreme: Wont start.Replaced and checked fuel pump,relay fuse,spark plugs and wires,timing chain,coil,ignition module,heres the thing,the pump comes on,gas is spurting out of test valve,I can put gas in the TBI and it runs for a second lets me rev it up then dies.I even cleaned the injectors I'm stumped can you help me?