[rondo]

Have a 1984 300zx Non-Tubo.The only way Ican get it to run is if I block off the return line,then it will run fine
but the idle is erratic. So far I have changed the fuel pump, fuel filter, fuel pressure regulator, fuel injectors and connectors, Mass Air flow sensor. If you unblock the return line the car stumbles and will not rev up and you cannot drive it. The fuel pressure is in spec. Running out of ideas. Please Help Me!

 

[bonfire79]

Do you have a copy of the FSM for the 84 Z31?
How was the engine running before you changed all those parts? (did it start having the issues after or before)
were the parts you changed actually bad?
did you adjust the idle control valve in any way?
have you checked for vacuum leaks? there are many vacuum sources on the VG30


fuel pumps are not known to go out on these cars

Bon

 

[rondo]

Do you have a copy of the FSM for the 84 Z31?
How was the engine running before you changed all those parts? (did it start having the issues after or before)
were the parts you changed actually bad?
did you adjust the idle control valve in any way?
have you checked for vacuum leaks? there are many vacuum sources on the VG30


fuel pumps are not known to go out on these cars

Bon

Yes I have a FSM for the car.
The car has run the same since I started working on it.Nothing I have done made any difference.I'am going to say none of the parts were bad because they made no difference.The injector plugs were all green and corroded but did not help.
Did not adjust the idle air control.
Checked for vacuum leaks with propane.
Without the return line blocked the car will hardly stay running, with it blocked I can drive the car and it runs good except the idle is erratic

 

[HenryD]

Have a 1984 300zx Non-Tubo.The only way Ican get it to run is if I block off the return line,then it will run fine
but the idle is erratic. So far I have changed the fuel pump, fuel filter, fuel pressure regulator, fuel injectors and connectors, Mass Air flow sensor. If you unblock the return line the car stumbles and will not rev up and you cannot drive it. The fuel pressure is in spec. Running out of ideas. Please Help Me!

Unplug the oxygen sensor and take it for a ride, I remember, these cars had very peculiar oxygen sensors that caused some performance problems when they started to malfunction.