I go with P.E.Haiges. You probably disconnected one of the vacuum hoses to the engine shut-off valve...
It is possible that the vacuum pod itself went bad, but that would be a real coincedence.
I presume that you didn't do anything under the dash (near the ignition lock or so)?
BTW: If this sending unit functions well, I wouldn't bother to exchange it for a new one. This used sending unit may last for a long time.
with a minor 600+k