fuel problem
 

Wondering if anyone has any ideas what this prob could be. I have a 69 ninety eight with a 455 everything original, virgin. Pulling it out one day and the crimp on the fuel pump (where it meets the cast housing and tin cover piece with the fittings, 3 ports) so I change it. K starts up runs fine purrs once it starts to warm up it stumbles then dies flat on its face. I'm thinking OK wtf so I check the filter, no gas. Got frustrated left it alone, come back the next day, pulled the air cleaner and filled the bowls, turned it over and I watch the filter fill back up, OK I'm good, it starts to just get warm again and I notice filter level going down not too steady it does fluctuate up n down but emptying nonetheless. I automatically think bad fuel pump even though it is new. Get another put it on, same thing. Car had no issues before. No vapor lock or anything. I thought it could be but fuel lines are not hot at all. They're not cold by all means but u can hold your hand there all day. I'm a pretty competent mechanic but man this ones got me. Any insight would be very helpful. thanks

Sounds like there is a rubber portion of the fuel line collapsing as it runs after a while...

Another thing it could be on a car that old is rusted hard line. All it would have to be is a pin hole and you'd never know it. The fuel is not under pressure from the tank so it won't just drain on you, but trying to suck fuel through a line with a hole in it....try it with a straw and you'll see what I'm talking about.