No, the cut off wire can't cause vacuum to be pulled through it, there shouldn't be any vacuum on that side of the unit. You can test the unit though by using a hand held vacuum pump by putting it on the hose nipple in the picture. Try spraying some carb cleaner around the areas of concern...carb, intake to head surfaces, brake booster & hose, ect. to notice a raise in RPM. Good Luck! Lorne