How can I siphon a full tank of gas from my “dead” Cadillac?
First…how old is the gas? Are you planning on using it in another vehicle? If it’s been sitting around for a year or so I would forget it. Most large hardware stores sell a siphoning hose with a pump attached. I don’t advise siphoning gas by mouth.
It’s not easy. You have to use a very small hose, get past the metal “trap door”, then the anti-siphon ball, then finally into the tank after rounding many twists and turns in the filler neck, and due to the small hose you have to use to get past the anti-siphon ball, it will take a long time to get an appreciable amount of gas, probably 1.5-2 gallons per hour. As missileman said, use a cheap siphon hose from a hardware store, and do not suck on it to get the siphon started. Gasoline will make you sick if ingested and will leave redness and burning irritation for days on any sensitive skin it touches, such as around the mouth and face. Been there, done that, never again.
Here are some examples of what you will be looking for. Do not use a battery operated one. Too dangerous, and generally not approved for flammable liquids anyway. http://www.walmart.com/ip/Pennzoil-Siphon-Pump/16795103
Remove the fuel pressure regulator. Adapt a hose on the fuel line that went to the fuel pressure regulator. Place the end of the hose into a gas can. Remove the fuel pump relay. Take a jumper wire and connect one end to the positive terminal of the battery and the other end in the relay socket to the fuel pump. This will allow the fuel pump to run to pump the gas out of the gas tank.