There needs to be vacuum to the fuel pressure regulator. Otherwise, it will allow the pressure to be too high. You can confirm that when you check fuel pump pressure. However, that could be the entire problem. Also, the vacuum to the fuel pressure regulator shouldn't come from the canister. It should have a constant vacuum directly from the intake. At an idle, intake vacuum is at its highest. As a result, the regulator diaphragm is drawn up reducing the fuel pressure. Under a load, the vacuum drops causing the diaphragm to lower and increase fuel pressure. If it isn't working properly due to a vacuum leak or no vacuum to the regulator, you are going to get too much fuel pressure all the time.
As far as fuel pump pressure, it should be between 35 and 40 psi with vacuum present at the regulator and at an idle.
Check that and let me know what you find.
Tuesday, February 17th, 2015 AT 6:08 PM