Quick question really baffled

[Doug Chahoy]

If it's a vent issue, it should cold start with the filler cap off.

Sounds like a problem Cadillacs had in the 70s , your strong fuel pump might be sucking the sock blocking the line . With everything you described , it seems possible

 

[85cutlassSS]

Sorry for the late reply but the culprit was the hoses on the sending unit they were dry rotted I replaced all them and the car took a few priming but it runs again without me having to blow air in the line

 

[Texas82GP]

Sorry for the late reply but the culprit was the hoses on the sending unit they were dry rotted I replaced all them and the car took a few priming but it runs again without me having to blow air in the line

Thanks for coming back and letting us know what the issue was. It's a service to the community to 'close out' a thread that discusses an issue.