To wonderboy918 & pdqman.
Willy made an interesting observation,while not being a fan of pumping air into the colon, he is correct.
[quote author=willy link=topic=30194.msg284502#msg284502 date=1269626477]
If the check valves on either side of the bulb are functioning properly there should be no problem sucking up the enema solution. At times, when the water is gone from the bag I will pump the bulb a few times and inject air into the colon. If the higginson is working at all you should be able to pump plain air.
[/quote]
These thoughts come to mind which you might find helpful:
1) If the valves are working properly,air or liquid will pass one way only.
2) The check valve(s) could be stuck open, some bulbs have two.
3) Some higginson 'type' bulbs have no check valves and won't work period.
4) At no time should the hose need to be clamped for the higginson to function.
It is not unheard of or uncommon to have these things occur, and is easily and readily resolved. The thrill of getting a rush of water on demand from a constant flow, a bulb's worth or partial is just that, thrilling. Another fun thing is just laying there pumping liquid in at your leisure as slow as you prefer if you like real slow fills that aren't from a hung bag and gravity is doing it's thing. I have done it both ways depending on my mood, in-line from a hanging bag for a "rush" or laying back and pumping a "leisurely" flow as slow as I like it. It definitely makes it worth the effort of checking into it.
Another thought, a very nice one way siphon bulb such as one used for pumping outboard motor fuel can be picked up at a variety of local stores. They are very sturdy,relatively inexpensive,have good long lasting valves, just be certain it is new and has never been used. Rubber has a porosity to it's surface and you don't want leftover residue from fuel or other chemicals going into your body, water will evaporate & dry leaving nothing harmful, other substances do not readily do so, and even if they do, will leave a residual film of whatever the chemical was. Hope this helps, if not, that's OK.
G.N.