Is there a potential link to use of Auto-LPG and fuel pump failure?

---

In some of our vehicles, an electrical relay was installed to activate/deactivate the fuel pump when LPG system was off or on. This was meant as a preventive measure because it has been observed in some vehicles that even with the LPG system running, gasoline (under pressure) is leaking through the closed fuel injectors. I am curious adding the relay can cause a condition for the fuel pump to fail prematurely?

---

I am also concerned with a potential problem with Auto-LPG use with cars with returnless fuel systems. Since there is no traditional fuel return line, the fuel is not moving and yet the pump is keeping the pressure in the fuel line. Will this static pump pressure condition have a potential to lead to premature pump failure?