Thanks y'all for taking time to help me cause I'm lost. I have a 1978 F150 with a 351 in it. It gives me trouble when I start it. Usually it take me as easy as 2-3 cranks to get it going or up to 12 then I just give up. When it finally starts it runs like a champ. I do have an inline glass tube so I can see the fuel pass through, it will be full when shut off but over time it will empty back into the tank. Leaving me wondering. I checked all the lines for leaks or cracks and nothing. I thought it was the fuel pump but like I said as soon as its running its a champ just getting it started is the thought part. Please help thanks

 

For some reason its not holding pressure and your fuel is draining back into your tank probably. My bet would be the diaphram in the pump.

 

So I replaced the fuel pump, and the issue is still occurring. I'm kinda itching my head on this.

 

The only other thing i can think is maybe your bowls are leaking itdown your throat into the intake.