1st2know wrote on 08/18/08 at 07:40:36:My Big Bang theory is that the vac line to the petcook is cracked or loose.
This happened to me. Shut the thing down, count to 3 and watch the birds scatter as the Savage relieves itself of surplus gas - It was fun, but I felt that the socially responsible thing to do was to fix it. Replaced the vac hose, tweeked the idle, no more bang.
I recently installed the ENM digital tach. During the process, I removed my tank to route the wires, which of course involved disconnecting the vac hose, etc. I put it all back together, and when I went for a ride the next day I pulled into the gas station and cut off the engine and had the same shotgun blast described. First time it ever did more than a mild puff at cutoff. Then when I got back home the same thing happened again at shutoff. BLAM! Had to pull my wife's cat down off the ceiling after that one!
Anyhow, I checked my vac line, adjusted the choke, dialed down the idle (the new digital tach makes it easy) and then drove a few more miles. Stopped & started it about 8 more times without more than a typical puff.
Next job is to patch the claw marks in the ceiling.