ON THE TOP OF THE CANNISTER IS THE PURGE VLV THE VERY TOP VACC LINE HAS TO BE HOOKED TO A PORTED VACC SOURCE SUCH AS THE DIST VACC LINE THE BOTTOM FITTING ON THE SAME VLV HAS TO GO TO THE MANIFOLD VACC PORT , THE OTHER LINE ON THE CANNISTER GOES TO THE VENT ,INE BACK TO THE TANK, IF THE VLV IS STUCK OPEN IT WOULD MAKE THE ENG IDEL TOO HI AND MAYBE STUMBLE OFF IDEL, AS THE THROTTLE IS OPENED THE PORTED VACC OPENS THE VLV AND LETS MANIF, VAC PURGE THE CANNSITER , THOSE THINGS RARELY GO BAD , UNLESS IT HAS PLUGGED VENT LINE IN THE BOTTOM OF THE CANNISTER , JUST MAKE CERTAIN THAT THE TOP VACC LINE DOES NOT HAVE MANIF, VACC ON IT , ALLSO IF YOU WANT TO MAKE IT IDEL REAL SMOOTH, ON THE NO 1 INTAKE RUNNER THERE IS A SMALL ABOUT 1/8 INCH DIA, HOSE PLUGGED ON TO THE NIPPLE, REMOVE IT AND PLUG THE NIPPLE AND THEN RUN THE LINE THAT WAS HOOKED THERE OVER TO THE LINE THAT IS PLUGGED INTO THE BOTTOM OF THE VLV ON THE CHARCOLE CANNISTER , YOU WILL NEED A SMALL TEE FITTING AND A LITTLE LONGER HOSE , WILL NOT AFFECT THE OPERATION OF THE CANN, AT ALL BUT WILL LET ALL CYL, HAVE AN EQUAL AMOUNT OF MANIFOLD VACC INSTEAD OF ROBBING ONE CYL AT IDEL , IT WILL RUN MUCH SMOOTHER JERRY