Chevrolet Repair: 1992 gmc sonoma 4.3z fuel pump, gmc sonoma, tank assembly

Question
VAN,    AFTER PULLING TANK TO GAIN ACCESS TO FUEL PUMP, I REMOVED PUMP AND BENCH TESTED WITH 12V.   PUMP OPERATED. DID NOT HEAR PUMP RUN IN TANK BEFORE I PULLED TANK !?!?  HOOKED PUMP BACK UP TO HARNESS AND GROUNDED--WHEN I TURN THE KEY ON , IT RUNS FOR 3-4 SEC AND SHUTS OFF....TRUCK WOULD NOT START AT ALL BEFORE I DID ANY OF THIS !  IS THERE ANY WAY OF KNOWING IF THIS PUMP IS BAD(INTERMITTANTLY) OR DOES IT SOUND LIKE SOME OTHER PROBLEM ?    THANKS FOR ANY HELP !

                               JIM

Answer
Hi Jim,
That ground wire may be the problem...it needs to be well connected.
I have removed and replaced pumps that I was sure were good, and found the problem to be the wires from the pump to the top of the tank assembly. There was rust on the inside of the top, and the rivet was loose where the wire connects.
It sounds like it is operating normally for you now. The three seconds is what it should do.
A pressure tester connected where you can see it can help, as well as a test light to see if voltage is getting back there, when the pump isn't running.
I doubt intermittent inside the pump, but that is possible also.
Good luck,
Van