Thank you for letting me join in to the forum! I have an issue that has me baffled. My 76 Cobra, 2.8 liter, will run for 30 minutes then run out of fuel in the line. Installed brand new tank, new sending unit,, new fuel lines, tried an electronic fuel filter but went back to manual, new carb, carb filter. Once I bleed out the air, it will run at idle for approximately 30 minutes then die. I had a clear filter installed before the pump and could see the fuel slowly decreasing as time passed. Changed everything back to factory (removed electronic fuel pump). Was recommended to do so by a friend of mine. But still have the same issue. I am pretty sure it's a fuel problem and not a problem with the electronic ignition, but right now, I am lost. Anybody ever have issues like this?
Thank you for any advice!

 

Maybe the gas cap? Sounds like the gas tank is creating a vacuum.

 

Sorry...forgot to add that I have a new gas cap also. Just tried insulation on the fuel lines and wrapped the exhaust with header wrap by the sending unit. Let it set at idle for 35 minutes and seem to do good. Drove it down the street and back then let it sit for the remainder of an hour. No issues. I am guessing it must have been vapor locking. Thanks for the advice on the gas cap though. Glad to see that there are still Mustang II lovers out there.