I had this problem, there is a small canister near the MAP sensor, one pipe goes to the engine, the other to the brake system. If the pipe has come off look down and under the brake distribution block you should see it T'ed in.

Its worth a check, good luck.

(My motor had burnt out so had to replace that first, if you can hear the motor running, it should be ok, but with the pipe off the canistor the motor will keep running and burn it out!)

Gav