fuel rail and pressure regulator suggestions-78 280Z

[Yarb]

Solved the fuel issue with the regulator. Went through the fuel system following the FSM doing static tests on each component. Next, checked each ignition device/controller. Measurements checked out. Replaced the temp/thermotime harness. I still need to replace the majority of the harness connectors. They are clean but brittle/broken. End result it runs but at high idle 1500 rpm plus. Tach is not working stuck at 3000rpm. Plugs are sooty but firing. The engine runs smooth but acts like the throttle is stuck. The static tests on the afm seem correct. Looked for vacuum leaks but nothing I can find. Need some help from the forum. I appreciate any suggestions.

[Zed Head]

29 minutes ago, Yarb said:

 End result it runs but at high idle 1500 rpm plus. Tach is not working stuck at 3000rpm. Plugs are sooty but firing. The engine runs smooth but acts like the throttle is stuck. The static tests on the afm seem correct. Looked for vacuum leaks but nothing I can find. Need some help from the forum. I appreciate any suggestions.

Have you adjusted the idle speed screw?  It's the screw with the big head and the spring underneath it on the throttle body.  You can turn it by hand.  When everything is right you can cause the engine to die by turning that screw all the way in.

[Yarb]

I have. The FSM Solved the fuel issue with the regulator. Went through the fuel system following the FSM doing static tests on each component. Next, checked each ignition device/controller. Measurements checked out. Replaced the temp/thermotime harness. I still need to replace the majority of the harness connectors. They are clean but brittle/broken. End result it runs but at high idle 1500 rpm plus. Tach is not working stuck at 3000rpm. Plugs are sooty but firing. The engine runs smooth but acts like the throttle is stuck. The static tests on the afm seem correct. Looked for vacuum leaks but nothing I can find. Need some help from the forum. I appreciate any suggestions.

[Yarb]

Thanks zed I,m familiar with that. FSM has it set for 6 revolutions cc. Even closing it down doesn’t help much. I was just reading the thread about removal of the bcdd. I removed mine and capped the vacuum port . The thread mentions plugging it internally. Any thoughts on that. Thanks

[Zed Head]

If you've run the idle speed screw all the way in and the engine still runs then you have a vacuum leak.  Then engine can't run without air and that's what the idle speed screw controls.

Check the PCV hose under the intake manifold. That's a possible air source.  I don't recall seeing any pictures of your setup and whether it's stock or not.  Wait...I went back and found your picture.  Even the valve cover port is connected to the intake manifold through the PCV system.  All of those holes have to be plugged.

If that hole is still open put your thumb over it while the engine is running.  Something will happen.

Edited November 17, 2019 by Zed Head

[Yarb]

I plugged It since that was taken. Also tried replacing the original hose back to the throttle body. I’ve replace the pcv ho se which was deteriorated. I followed your previous advice where you mentioned to go by the FSM and check check and check again. I’ve done all the testing That was in the FSM using my meter including the ignition controller on the passenger kick panel when I had the run problem. Plating off the bcdd might be my issue. What do you think?

[Zed Head]

People have found leaking valve cover gaskets,  Leaking injector seals.  The BCDD is a possibility.  It has a rubber diaphragm inside that can split.

Vacuum leaks are a B.

[Yarb]

It’s just nuts the rpm it’s running at. Certainly not driveable. Really want to move on and get going on the suspension and 5 speed conversion.☹️

[siteunseen]

I had a big vacuum leak that took a while to find.  It was where the EGR tube connects to the intake closest to the fire wall.  It had come loose and over time the hot gases from the EGR rotted away the aluminum intake.  It was close to the size of a golf ball.

Here's a picture after the fact but you'll see if it's loose or not.  You might see it best with a handheld mirror?  It's on the underside, the picture was taken with the old one on my bench.

Here's a better picture showing the general location.

After some coffee I realize now the tube was most likely the one from the exhaust.  I honestly don't remember

Edited November 17, 2019 by siteunseen

[Yarb]

Thanks, that does point me to an area where I removed the rotted egr and plated it off. The metal vacuum line going into the back of the intake was seized. I was able to back the fitting out but not able to remove the tubing. Ended up cutting the tubing and capping it. There’s a good chance that didn’t seat properly when I ran the fitting back in. As tight as it is I assumed it was sealed. Tomorrow I’ll spray some starting fluid back there and test it. Zed suggested looking at the pcv system. Replaced the hose at the block to the pcv. The aftermarket replacement was not a true fit. Had to really stretch it to fit. I’m amazed yours ran with that giant hole. Thanks for the pic. 

[Yarb]

Still have a major vacuum leak. Did find the afm not closing completely. Solved that hoping that was the issue. No luck. Isolated the vacuum advance by capping it at the throttle body. Sprayed either all over nothing there. It’s sucking a lot of air some where. Pcv system is tight. All I have left is I capped off the bcdd valve and sealed it with permatex. valvcover gasket is old. It’s running around 2k rpm. Ran the AFM  bypass screw all the way in with no result. Help from the Forum would be GREATLY Appreciated

[Yarb]

Another test I have not tried is plugging the AFM completely.