Astros/Safaris stock fuel pumps have been known to fail after 100k miles. Usually the pumps don't stop completely, instead they get too weak to start or run the van. The pumps most ofter can still be heard working which leads to mis-diagnosis of the no start and lots of needless parts swapping. The best way to check a fuel pump is to use a fuel pressure gauge on the fuel pressure check valve located in the fuel line on the rear of the engine, driver's side under the interior engine cover. 1996 and later vans need 58-64 psi to start and will run in the mid to upper 50s.
For many a dead pump seems too much to bear, as the dealer will want somewhere in the neighborhood of $900 to replace it. All pumps can be replaced for less than $350 by anyone with the ability to turn a wrench. A word of warning though, stay away from non ACDelco/Delphi pumps that are available at the chain auto parts stores, as they do not last as long as the stock pumps resulting in yet another pump replacement.
Fuel Pumps / Assemblies
http://www.gmpartsdirect.com
http://www.rockauto.com
ebay Fuel pumps
While there are some merchants that do sell ACDelco/Delphi pumps, there are several more that can confuse you into buying lower quality pumps by listing the ACDelco/Delphi part numbers. Usually with these sellers there will be a list of compatible part numbers instead of just the specific ACDelco/Delphi number. When in doubt, question the seller before committing to the purchase.
Also note, that for the newer vans that usually require replacement of the entire fuel pump assembly there are a few sellers offering cheap rebuild kits. On the Astro/Safari forums only one person is known to have tried a rebuild kit so far and while it's still working, it is not recommended for long term reliability as of yet.
Fuel Pump Replacement Instructions
Disconnect the wiring harness.
If still present, remove the L shaped plastic shield from the passenger side of the gas tank.
In the space between the tank and the drive shaft close to the floor, disconnect the fuel supply and return line connectors. These would have been made visible by the removal of the shield. While repair manuals call for a special tool to release these connections, it's possible to release them by pressing the tabs with a couple screwdrivers.
Disconnect the fuel filler neck.
Support the tank. A couple cam-buckle straps have been proven to be well suited for lowering and raising the tank.
Undo one bolt per tank strap and rotate the strap clear of the tank. The passenger side bolts usually come out easier since they don't get as much wheel spray.
Lower the tank. (1 gallon of gas weighs about 6.1 lbs, so 27 gallons of gas weighs about 165 lbs)
Transfer the fuel lines to the new pump module. (1996 and newer)
Remove the fuel pump retaining ring. Might be a twist or snap ring depending on year.
Remove the old fuel pump module.
Replace the fuel pump and strainer(1995 and older)
Reverse to install.
Make sure you don't cross the fuel lines as two have the same size connectors and the van won't run right.
Install a new fuel filter (These should be changed at least every 20k miles)
Fuel Tanks
1985-1989 - 17 gallons (I4 engines)
1985-1996 - 27 gallons (V6 engines)
1997-1999 - 25 gallons
2000-2005 - 27 gallons
Source: http://car-part.com/ and http://www.kbb.com/
Fuel Filler Neck Hose
Size 2" ID x 6 3/8"
NAPA - NBH 1045