How many fuel injectors does it take for my van

Are they getting gas?... if so bad injectors maybe clogged
If no pressure to fuel rail then clogged fuel filter or bad fuel pump

Impurities getting into injector (you may need to replace your fuel filter) and/or water in the fuel.

And you know the fuel filter is good? Could be injector problem: just as a check, spray some starting fluid into the intake and see if engine runs a few seconds. If it does, it is a fuel problem. Check injector fuse, as a start. Check fuel pressure. Check injector circuit. If engine won't start with starting fluid, check if you are getting spark. Problem may be in the ignition system.

Unless you have a clogged fuel line going into the throttle body, something got missed.
With the key on, can you ground one of the injectors and make it spray ?

install a fuel pump guage and check pressure at key on and start, it should hardly vary, it the pressure is constant check the injector signal with a noid light, while you are at it check spark(no spark no injector signal) you won't find a relay fuse

This van is TBI right? then its only 14psi of fuel pressure. to check fuel presssure a adapter is needed at the filter. I would verify fuel pressure first.

SOUND LIKE SEVERE ENGINE MISFIRE HAVE VAN SCANNED AUTO ZONE WILL DO IT FOR FREE .BUT MAKE SURE FUEL FILTER NOT STOPPED UP MAKE SURE PLUGS AND WIRES IN GOOD SHAPE.FILL FUEL TANK UP.PUT A BOTTLE FUEL INJECTOR CLEAN IN FUEL TANK.TO CLEAN OUT FUEL INJECTORS WHILE YOU DRIVING THE VECHICLE.ALSO BAD COIL OR COILS WILL CAUSE ENGINE TO MISFIRE SHAKE.

THE FUEL IS PRESSURIZED BY A FUEL PUMP INSIDE THE FUEL TANK, THE INJECTORS ARE OPENED AND CLOSED ELECTRICALLY BY THE FUEL INJECTION COMPUTER KNOWN AS THE ECM, THE COMPTER/ECM RECIEVES INFORMATION ON WHEN TO INJECT FUEL AND FIRE THE SPARK PLUGS FROM THE CRANKSHAFT AND CAMSHAFT POSITION SENSORS, HOPE THIS HELPS

it is most likely the pump because with a clogged injector it would still get gas in the other 5 injectors

check harness to the injectors seen aot of these where the harness gets short to grond at the base of the throttle body to air cleaner and they saty wide open! check that harness!