Might improve the situation and perhaps simplify with these few ideas.

1- Connect the electric pump after the filter, that way fuel to it is filtered.

2- Skip the check valve and instead connect the electric pump in parallel with the original fuel pump. The original fuel pump has two check valves already. With the pumps in parallel you don't need to add another check valve (in your drawing) that is also a further restriction in the suction line for the primary pump.

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-