No fuel when tank is 2/3 full

[Aruba1]

Sorry if this is a common problem covered that has been covered in the past but I have no clue what keywords to use, lol.

Truck is a 1972 with a 383 bored over 30, a Holley and electric ignition. Here is the deal, when the tank is about 2/3 full, sometimes the truck won't start (no fuel at the carb). If I spray some starting fluid it fired right up, idles and drives fine. For the next week or so it will continue starting fine. Last month it did the same thing when it reached about 2/3 full. The tank is clean and as far as I can recall the pickup tune looked fine when I checked them a few months ago. At that time I replaced all the fuel lines and fuel filter.

Can anyone tell me what is wrong with my truck? Thanks

[geezer#99]

Could be vapor lock!
Do you have a vented gas cap?

[justin4260]

are you choking it?

[Aruba1]

I just checked the cap and it's not a vented cap so that must be the culprit.

My truck does not have choke but I never missed the choke.

Thanks!!