Where is the fuel pressure sensor and should the resistance be.

Question

2007 Mazda CX7 Grand Touring: where is the fuel pressure sensor.  Red and black wires go to the top of the high pressure pump; is that it?
Fuel pressure at idle is 2280 psi and appears to be regulated by the relief valve.   P0193 code thrown immediately on start, but no other codes. Engine starts on two cylinders and runs poorly, but fires on all at idle.  Sometimes blows back through the intake manifold like an intake valve is not closing.  New short block has about 800 miles on it.  Injectors and turbo are new.  Spark plugs (new) show rich mixture.  I am guessing a bad pressure sensor, but can not find it for sure without removing half the engine to get under the manifold.  Any suggestions would be helpful.

Answer 1

Here us this for the location. In order to set a P0193 you would have a open circuit to the fuel pressure sensor. this means it reference voltage is no connected , that or its sensor ground is open which is part of the CAM position sensor and the CKP sensor. Even with a P0193 the engine would start. But for the rough idle , more inspection for the fuel pressure sensor PCM ground is needed.

​The PCM sensor ground if there a fault connection there not only would you set a P0193 but the camshaft position sensor and the CKP will get skewed information and the rough idle.