It is always easier to help someone with a problem if they continue on with their original post. You had several responses to your original post, if you had continued with that and replied after trying some of the suggestions, it would be easier to help you
Definately agree with staying on same thread as Denny47 mentioned.
I browsed thru your previous posts. Seemed you had a leak around the petcock before. Did you rebulid it? Did you switch to another type of shut off valve?
If you search the forum for these topics you will find valuable info and strong opinions regarding petcock versus pingle, Dan Marc electric shutoff valves etc.
Always make sure the overall length of fuel line stays at original length. If it is longer it will create a "low spot" and the gravity feed fuel will not flow properly and cause fuel starvation.
Depending on what you have done under the tank so far I would suggest the following:
1. Order Petcock "Cover Set" and rebuild the internals
2. Make sure fuel line is OEM lentgh
3. Make sure tank vent line is in good condition, not kinked, and still has the plastic "T" about half way down.