knocking noise

im trying to figure out what it is.. it is a knocking noise, like three really fast knocks.. sounds like it is coming from the fuel filler area (drivers side)

i have heard it in my car, and my dads car (02' impala)

anyone else hear this noise? what is it?

Start with what car this is?

Start with what car this is?

both cars do it, it is three very fast knocks.. doesnt do it all of the time

usually does it within the first 5 minutes of startup/driving when everything is mostly cool

literally it sounds like someone is outside knocking on my car trying to get my attention

both cars do it, it is three very fast knocks.. doesnt do it all of the time

usually does it within the first 5 minutes of startup/driving when everything is mostly cool

literally it sounds like someone is outside knocking on my car trying to get my attention

One more time. What kind of car is this? Although we might be a little psycho here, we're certainly not psychic! Since we can't read your mind, you have to tell us what you have.

We are done here if the car/engine in question is not posted!

its in the first post....

There are references to two vehicles. The question was fairly straightforward. Cryptic replies aren't going to help, so we might just as well call it done.

Ok!