More likely the valves in the lift pump are not sealing at all. The primer pump uses the valves in the lift pump to get fuel on the upstroke and seal on the downstroke.

A good preliminary test is the primer pump should get harder and harder to use until the relief valve on the injection pump opens. This usually makes a kind of squeeling noise.

If this is not happening and the pressure of the strokes is remaining constant. I would rekit the lift pump.

If This car used waste vegetable oil for fuel the odds of a problem in the lift pump existing also increases .