Remove the fuel suction line going to the fuel pump.
Tee in a vacuum gauge into the pump and the line. Start/crank the engine over.
Is the reading on the gauge greater than 1.5–3.0 kPa (6–12 in. H2
If yes, check the suction line from the fuel pump to the fuel tank for a restriction (bent, kinked, or internally collapsed). If there is no damage, check the fuel filter, and get customer approval to replace the filters.