[jhv48]

I would disconnect, or bypass, first one and then the other fuel pump and see if the problem goes away.

If it doesn't, then I would look at the fuel filter. Then loosen the gas cap and try it.

Something is restricting the flow of fuel. Could be collapsing fuel lines, plugged or no fuel tank venting, etc. But my bet is that one of the fuel pumps are the cause.

I, too, question the use of two fuel pumps.