I installed a B&M Fuel Pressure Regulator and then the next day took car to the dyno and had it tuned. Now in the morning my car does not want to start. It's starts but it idle's @500-600 rpm and then dies sometimes. I looked @ Fuel Pressure Reg while the car was running it was @ 42 psi but the needle was moving up and down but staying on 42psi. Anybody!!!!!!!!!!!!help!!!!!!!!!!!!!!!!!!!!Thanks.

 

did anything happen at the dyno whats your a/f ratio on the car you might have a leak somewhere. check for the smell of fuel in the engine bay also how is the fp gadge moving and staying on 42. try checking for and leaks (vacume) also and pluging things in and out like the tps and map sensor and such.

 

Make sure that setting is when the vaccum line is disconnected.
With vaccum line connected it should read way lower than 42psi.
other than that..
42psi is kinda high. Believe it or not half a psi makes a difference.
You might be flooding it.