1976 280z engine runs rough then dies, will not idle.

[Dave WM]

if you have no vacuum with with the engine running you are going to have to start listening for an air leak, if its not the EGR anyway (doubt you could hear that). some other leaks

missing o rings on injectors, stuck open PCV with massive hole in PCV hose, split vacuum lines. Bottom line is if no vacuum you need to find the leak. Some folks use smoke, plug up the TB inlet, break out a stogie and puff into the brake master vacuum port, look for smoke,

[Zed Head]

42 minutes ago, mbz said:

Yes on March 31st tests:

4). Fuel Pressure while Sucking on the vacuum hose from the FPR = 40 psi [PRESSURE DOWN]

However... I was just sucking on the vacuum line of the FPR when the pressure dropped. I did not test vacuum coming from manifold.

So, at this point the next step is to pick up a vacuum gauge and check the intake manifold vacuum going to the FPR?

If so, I'll be at harbor Freight first thing in the morning.

Just be sure to separate the two things, in your head.  You're planning to look at why pressure isn't reducing from an already too high baseline number.

[Dave WM]

I mean really, you could just hold your finger over the power brake port, if you have a vacuum you will feel it. Question do your brakes feel like they have power assist? That's another place you can lose vacuum (brake booster).

I had a brake booster give out on me, it would leak every time I applied the brakes. engine would die.

Edited April 13, 2019 by Dave WM

[mbz]

3 minutes ago, Zed Head said:

Just be sure to separate the two things, in your head.  You're planning to look at why pressure isn't reducing from an already too high baseline number.

Yes I understand, and am starting by checking for vacuum reading from the intake manifold that goes to the vacuum line of the FRP.

[mbz]

2 minutes ago, Dave WM said:

I mean really, you could just hold your finger over the power brake port, if you have a vacuum you will feel it. Question do your brakes feel like they have power assist? That's another place you can lose vacuum (brake booster).

The brakes do not feel mushy (like pressing a marshmallow), nor too hard (like pressing a brick). They feel "normal". Brake fluid levels are good.

I did disconnect the vacuum line to the brake cylinder a few weeks back while engine was running and the engine idle went up very, very high, and the idle adjust screw was able to adjust the idle.

[mbz]

Just reading up on the EGR valve, and I can't help but wonder if this all goes back to what was mentioned wayyyyyyy back at the start of the thread, maybe it's a bad water temperature switch?

[Dave WM]

and you can feel a suction at the port on the intake then? if that is the case something is just not adding up.

 

[mbz]

Just now, Dave WM said:

and you can feel a suction at the port on the intake then?

Not sure I follow......

[Dave WM]

finger over brake port on intake does it suck.

[Zed Head]

I think it was covered a while back, but the FPR vacuum line is connected directly to the intake manifold.  If you have brake booster vacuum you should have FPR vacuum.  On the other hand there is a ported vacuum line that only gets vacuum when the throttle blade is not on idle, not closed.

 

[Dave WM]

if you have a cali car, which I think you do, then the water temp switch turns of until the water is warm. You should not have a vacuum at the EGR when the engine is cold, you can just un plug the vacuum line from the EGR valve. BUT I doubt a malfunctioning water temp switch controlling the EGR would cause this much issue, unless the EGR is hooked to the wrong vacuum port, It should only get what they refer to as "ported" vacuum. The other problem is if the valve it self is stuck open. You need to remove it clean it, and test it for function by applying vacuum to it and seeing if it works as it should per the FSM.

[Dave WM]

Maybe you should take a pic of some of the vacuum hookups, specifically the FPR and the EGR.

Edited April 13, 2019 by Dave WM