How to install fuel pump in chevy 2003 astro van pump not putting out fuel i put new relay in. no sound coming from old pump no fuel coming through line. i disconnected fuel filter and left line open. i turned on ing. switch nothing flowing from pump

Its either got a clogged fuel filter or the fuel pressure regulator is bad.

You removed the relay and put back in, and it can start? It could be a relay going bad or a wiring terminal connection where the relay plugs in. I would try a new relay and see if problem goes away. Clean the terminals with an electronic cleaner spray, where the relay plugs in.

chk in line fuel filter for obstruction, also could be a lot of sediment in the tank clogging up the filter. Hope this helps you resolve your problem.

I'd check for a fuse to the pump relay.

my chevy full size van 5.7 litre has fuel coming from the fuel pump all the way to the engine but wont run. It will run if i put gas into the intake manualy. I put new relay and changed filter. fuel pump is working

fuel pump relay is under the hood in the fuse/relay box. information is in your owners manual.
when was the last time you replaced the fuel filter, maybe its plugged?

Sounds like dirty gas and the fuel filter is clogged...try changing the fuel filter...some are under the car, but most are mounted against the firewall in the engine compartment.

Check to see if the fuel pump is kicking in,
when you turn the key on without starting the van you should hear it kick on for about 2 seconds,

It could be...
A clogged fuel filter...
Blown fuse for the pump..or bad pump relay..
No gas
Bad fuel pump

What does the van do when you try to start it? Does it try to turn over or does nothing happen when you turn the key?

Injectors or Carb? is there fuel presurt to the line near the engine and what is the presure.
The mechanoc was it a shop or buddy at home? Can you hear the fuel pump run when the key is turned on?