On a van, if it still has it, there will be a pull handle next to the transmission dip stick. It is D-shaped, and it has a lawn-mower type throttle cable sort of thing that actuates the water drain. If you pull the handle, it will drain the bowl.
Most of them don't have this any more since it is a pain in the butt, and even if it does open the drain, it probably won't work to close the drain again.
If your van does have this, and it works, great. If not, then you have to remove the air box, and work your fingers behind the filter housing, and flip the yellow lever open.
Another hint about vans is that they have a resonator box attached to the intake tube. It is useless, and it's a pain in the a ss. I would suggest removing it by any means that please you (I usually use a large chisel and a hammer) and plug that hole on the side of the intake tube with spray paint can lid. It makes maintenance on top of the motor much easier. Another thing to do is loosen the clamp (slightly) that holds the intake tube onto the plastic housing on the driver's side valve cover. This will let you pull the tube out to check your fuel filter and such more easily. Just give the tube a tug, and it will pop off. Then to put it back on, it will slide pretty snugly back on the sleeve. When the engine vacuum gets a hold of it, it will hold in place perfectly. Not to mention that the front end of it is secured with the air box.