I've been having issues with my Max and I've got it down to a fuel issue rather than spark/ignition(symptoms are delayed starts, hesitation, stumbling, putt putting until 3000rpm). Plugs, wires, cap/rotor, dizzy/sensor, coil, ignitor, ect.. are all within spec. My injectors are all within spec, injectors cleaned/replaced cracked connectors, injectors sound right listening with screwdriver method, couldn't find any vacuum issues, new fuel filter and new fuel pump. Anyway, i hooked up my fuel pressure gauge between engine and fuel filter. The fuel pressure reading is below spec at a shaking 28psi to 30psi, the needle is shaking back and fourth but it holds pressure at key off. I want to know where the fuel pressure regulator solenoid is on my 89' GXE so I can test it for source voltage. If this solenoid is good then I'm thinking the fuel pressure regulator is on it's way out. I found a crack on the power valve control solenoid and it's in the black circled section to right of plug.
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There is no solenoid that controls the fuel pressure regulator. The regulator is controlled directly from a vacuum hose that's connected to the intake manifold. You will see that small hose next to the brake booster hose.

So what you can do first is change the hose and see if it improves. If not, then it could be the regulator.

 

There has to be a control, something that tells the vacuum what to do. In my picture I'm showing a power valve control solenoid but I'm trying to see if this is the right one. Thanks for your input bro.

 

You can say that the throttle takes care of the vacuum. I guess Nissan didn't see a need for an extra control for the fuel pressure regulator.

And the power valve control solenoid controls the variable length intake butterfly valves inside the intake only.

 

those are always cracked on the 3rd gens i see, i always figured its just the plastic body
thats cracked and there is an internal valve which is hopefully metal

does anyone know for sure

 

Naw I think its all plastic. Anyone I knew with a cracked one immediately replaced it.

 

So I should replace.
.

 

yes...rev the car in neutral and see if the power valve moves. if it moves then you might be ok. if not then swap it out. it's good idea to swap it anyway if it's cracked like that.

 

Yeah better safe than sorry. If it is ok it won't be for long.

 

Looks like it's the fpr.

 

i better check mine self less i vacuum leaketh my valve

 

What are the odds? (usually high) You go in to look for one issue and discover another. Thats my car everyday all day.

 

After testing fpr with a pump it failed but the power valve control solenoid is also faulty.

 

The plunger should move inwards towards the connector right?