K75S fuel pressure regulator testing
I seem to have lost the followers on my previous thread re fuel issues so here's the question. I have reason to believe that my fuel pressure regulator is stuck closed. To try and test this I disconnected the return line at the fuel rail and tried blowing through it. I couldn't move air through it using my mouth so I applied approx - 25psi on the vacuum hose after disconnecting it from the throtle body and still could not blow air through the return hose. Does this indicate a malfunctioning regulator or am I totally misunderstanding the operation?
K75 fuel pressure regulator
Thanks for the reply, kkeller. I know that the regulator is supposed to control the pressure at the rail but what is the function of the vacuum line if not to relieve pressure? At the risk of sounding dumb, if the pressure is controlled simply by spring loading in the body of the regulator, why is there a vacuum line connected to it in the first place? I assume there is no good way to test the regulator except through pressure testing and/or exchanging the regulator.