how to figure out how many GPH your fuel pump does?

[451Mopar]

When I was converting to EFI, I tested 3 different EFI pumps and a few filters.
All of the pumps (in-tank type) 255 LPH, 340 LPH, and 450 LPH delivered the rated flow.
For the filter tests, I put a "Y" in the fuel line and filled two different fuel canisters thinking that if one had more restriction to flow, one canister would fill quicker.
The results were the cheap filter seemed to flow as well as the expensive filter. The larger expensive filter just has more area so it should not get clogged as often as the small cheap filter

 

[BSB67]

There are a lot of variables associated with what a motor and its associated fuel system conditions needs relative to manufacturers pump ratings.

We can all speculate, hypothesize and theorize on what manufacturers pump rating will work, but until you try it, you won't know for sure.