2007 Chev Express G2500 crank no start

hello everyone 

I have a problem here this 2007 chev express van was towed in this past Monday with a no start. l was away Monday and the apprentice diagnosed it as a fuel pump. so when l came in the next day the boss put me on it . found out fuel pump didn't fix it . So l got the power probe out and found out there was .5 volts at the fuel pump and l had ground.

so here's what l did
-cleaned both frame grounds on left side of van
-back probed wire at ecm for the fuel and had 12v
-checked for voltage at relay in power distribution box had 12v on pin 87
-back probed grey wire that runs to fuel pump and got 1.5v coming out.
-check braided ground wire from block to frame near RF wheel it was good.

so I called the power distribution box. got new box and put it in and had 9.5 volts at fuel pump and 8.5 volts when cranking. put battery charger on through lunch and came back and had 12.5volts at pump so l was like good it'll start but when l plugged in pump the grey wire at pump flipped to ground when l backed probed it. 

today when l came in l had 1.5 volt at pin and 1 volt cranking. so l wanna know what I'm missing or do l have another issue.

wrote:

-checked for voltage at relay in power distribution box had 12v on pin 87
-back probed grey wire that runs to fuel pump and got 1.5v coming out.


 

Is the 1.5v coming out, with the relay energized. If so, there is your problem. With the relay energized, verify 12v coming in on relay pin 87. You should, also, have 12v coming out on relay pin 30.

What voltages do you have on pins 85 and 86?