okay well then you can see if the venturi that comes with it originally in the box fits the intake, but you'll have to see, as it is designed to fit the outlet. Otherwise you can make your own venturi by using a piece of PVC or other tube, drill a hole in the top, and fit a piece of airline tubing in it. Make a |/ kind of cut at the end and face the flat part towards the outside, angled part towards the pump. That should work as a ghetto venturi. You'll probably want to put an airvalve on the airline, as you want to be able to control how much air gets in.
BTW, that is the ghettoest solution I can think of. I don't think they make venturis for maxijet pumps anywhere, otherwise I would suggest just buying theirs.
Hopefully some of that made sense.