Steve,

your post mentions it is a carburator model. It is possibly equiped with a SU or Zenith-Solex carburator.

There is no in-tank and secondary electric fuel pumps on these cars. The fuel pump is mounted at the bottom on front left side of engine and is mechanicaly driven. There is is mesh type filter at the fuel tank suction pipe but no element cartridge type filter.

I always installed a metal cartridge filter on my carb. volvos(67, 72, 81 and 82). It solves the problems that occurs with dirty or high moisture fuel.
In the 240 I install it half way between the pump and the metal line that ends at firewall. Use new good quatity hoses and clamps. A leak there is just over the starter; it is why I use metal cartridge instead of plastic. I do not suggest you put it there but it has worked ok for me.

It is a good thing to remove carb. and clean the float chamber, check float needle and level just to make sure the problem is not there. On my 122S twin carb. I encountered many times fuel overfow due to dirt at the float needle, this is when I started using online fuel filters.