When my '92 Corvette popped the diaphragm the first symptom was hydro-lock when attempting to start. No warning. It just didn't turn over one day. Then it dripped fuel from the headers for 6 days in the garage until I jacked up the front of the car. It's a relatively high mounted fuel tank so it was siphoning fuel into the intake as it sat. To fix, it just needed a new regulator and two oil changes. As they said above, just pull the vacuum hose and check for fuel.