Connect a vac line from a known good source directly to the shutoff
with the engine running. If it doesn't stop instantly, the diapram is
shot, replace it.
You should also check for vac at the servo line with the key out,
engine running -- if you have good vac in the hose, the diaphram is
shot. If you don't have vac, check for cracks in the plastic lines,
they do get brittle with age. Also check for plugs in the connection
for the brown vac line to the main vac line -- if that orifice plugs,
it won't shut off. Don't drill it out, it's fairly small.
If there is oil in the brown with blue stripe line from the shutoff,
for sure the diaphram is gone.
Peter
