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Hello all 1991 300zx Nissan twin turbo is the vehicle I'm working on ""Cranks but no Start". I have power and pulse to fuel injectors, fuel pressure by the fuel filter, compression. before I pull off intake manifold to get at the injectors I pulled the fuel rail to make sure no restrictions. There is a fuel damper and a fuel pressure regulator on rail. Damper seems ok but regulator is like a brick wall nothing can go through. no throughput when I put vaccum to it and send a little pressure down line. Do these things go bad? how do you test? Car was sitting 8 years trying to bring back to life.
On a normal tradditional style fuel injection system the pressure regulator functions exactly like a safety valve on a steam boiler or an air compressor tank. Only when the specified pressure for the system is exceeded will the regulator pass fuel back via the return line to the tank to control (ie reduce) the pressure in the fuel rail.
Normally key on at idle or with the key on engine off there will be a steady stream of fuel bleeding back to the the tank,
Injection systems normally run at 3 to 4.5 bar above manifold pressure -- 45 to 75 psi
If you suspect the engine isn't getting fuel try introducing fuel (ie Propane) or "EeezyStart" into the manifold -- taking care when spraying flamble substances. If it fire with the propane in the manifold it looks like a fueling problem if not look elsewhere ie ignition.
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