Fuel regulator failure.

[gatso]

What could be causing a fuel pressure regulator to fail.it s the second regulator that fails after 100km

[Wobba]

You mean the one on the fuel rail? How do you know it is that at fault?

[gatso]

yes.the car was missfiring and black smoke get out from the exhuast when it was getting hot.After changing a lot of things like injectors,o2 sensor,crank sensor... i tested the fuel pressure with a gauge.When i turned the key to the on position and the fuel pump was senting fuel the gauge was raising to 2 bar and immediately fell down to 0.I disconected the return line and noticed that the fuel was coming back to the tank.i blocked the return line turn the key back to on and the fuel pressure was steady.So i ve changed the original weber regulator with a bosch.Car worked fine just for a week.Again with the pressure gauge checked the pressure and had the same symptoms.So i changed for a second time the regulator and car worked fine again.I have the second one for 150km,it hasn t failed yet,maybe the previous was faulty but i was wondering if there is anything that could cause the regulator to fail.