[MARKDTN]

You are trying to suck through a filter and it is clogged with rust. That could definitely be the problem. As said above, those pumps are not meant to suck through a filter. And the only difference in a 5/16 and 3/8 inlet is the inlet, the filter element itself is exactly the same. I once added a filter to my '83 K20 right where the tank splitter valve would go. I added it at the same time as a new Delco fuel pump. About 6 months later it killed the pump. I took the filter out and moved it between the pump and the carb. Pump lasted until I changed the engine to fuel injection.

If you are having rust issues, you will not be able to "stop the bleeding with a bandaid" You are better off fixing it now than being stranded beside the road or losing power in traffic.