Summary: warm engine re-start attempts results in violent sucking sound from fuel tank area

After driving the the XK8 (1999 with 45,000 miles) for 10 to 15 miles, then parking it and tuning off the engine for 30 minutes or more, an attempted restart results in a violent sucking sounds and rattling sounds (similar to the sound a straw make when you are trying to get the last of a soda out of a cup). It will then not start or idle like a cold engine, but instead it requires pumping of the accelerator pedal to get it going again and only after several attempts.

When starting the car a few days later, it started cold and without the noises. Considerable gas fumes are occasionally present. I am guessing the noise is the fuel pump trying to pump fuel up to the engine but having trouble doing it. Or, could this be a vapor or injector issue? I just don’t know. Any help will be much appreciated.

 

Sounds like flooded car. My guess is a leaking fuel injector. Pumping the pedal on your car does nothing except allow more air in which is why you are eventually getting it to start

The next time it happens, hold the pedal all the way to the floor and see if it starts faster. Then find the problem and fix it!

 

It's been mentioned before. As fuel is getting burned, it needs to be replaced with air in the tank. There is a setup for that, possibly by the gas cap (not sure, never happened to me). It has been reported before that this vent can clog as cause problems. Be careful as this issue can lead to the gas tank collapsing under atmospheric pressure and high vacuum from the pump.

Best of luck, keep us posted.

 

I recall reading about collapsed fuel tanks on the XJ6 forum, failure of the vapor control valve (Rochester valve) CBC7714 being one of the causes. But I believe they are no longer available. Plugging of the fuel tank vent line or charcoal canisters is also possible.