I'm changing my fuel pump so the tank is out. Now I know the nutted line is pressure, one is a return, one is a vent to the charcoal canister, so I assume the white piece on the remaining line is a one way air intake? I can't seem to draw any air into or out of it. I'm wondering if it has failed and it's leading to pump failures. This will be my 4th pump in 10 years including the factory one.

Never mind, found out.

Hey man, Im having pump issues on my 91 RS 305 TBI. When your pump fails, can you jump it to get it started, or does it not run at all?
My car will not start when its cold, but if I jump it, eventually it fires up, then it will start fine as long as its warm. A friend works at NAPA and he thinks my pump is weak and needs replaced. Any help would be appreciated. Maybe some pics of the tank removal if you have them.
Thanks

I'd be checking your fuel pump relay first. If it stays running once it starts then its not your fuel pump. After it starts, its oil pressure via the oil pressure switch that keeps it running. It sounds like your not getting a fuel pump prime. The relay is supposed to prime the system by turning the pump on to pressurize the system. It takes 4 psi of oil pressure to close the oil switch. Cranking the engine will eventually build enough pressure to close the switch and power your pump.

I just saw that your TBI. There may be some differences in the fuel system as I'm EFI but I still dont think it's your fuel pump.

Im pretty sure its fuel related, but the fact that it will run once started has got me stumped. Do you happen to know where the fuel pump relay is located?

On the EFI its located on the drivers side FireWall just to the left of the Master Cylinder/Booster assembly.

You never did tell us what the white valve is...