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

[S30Driver]

3 minutes ago, mbz said:

Would that be just a matter of connecting a vacuum gauge to the manifold where the FPR vacuum line connects?

Yes, that would work.  The vacuum warm at idle should be around 18" or so.   I suspect it is low due to a leak.

[mbz]

Just now, S30Driver said:

I suspect it is low due to a leak.

A leak in the intake manifold (like the gasket...?)

[Zed Head]

There are many possibilities for running rich.

The opposite of assuming is confirming.  Or pretty close anyway.  Assuming is bad, confirming is good.

[Zed Head]

53 minutes ago, mbz said:

Fuel pressure with only fuel pump on is 40 psi (should be 36 psi).

Fuel pressure while idling is 40 psi as well.

Pretty sure that you saw a pressure drop with vacuum in your earlier tests.

You just have to break this down in to its pieces.  The gauge, the FPR, the flow path, blockages, etc.

No offense S30Driver, but his baseline setting isn't even right.  Vacuum comes next...

Edited April 13, 2019 by Zed Head

[mbz]

1 minute ago, Zed Head said:

Assuming is bad, confirming is good.

I thought someone else was Captain Obvious! ?

[S30Driver]

4 minutes ago, mbz said:

A leak in the intake manifold (like the gasket...?)

As Zed said, there are many possibilities.......  the pcv hose, egr area, injector seals etc.

Its a sealed system, good news is, if its a big leak - easy to track down and find...

Edited April 13, 2019 by S30Driver
added content

[mbz]

7 minutes ago, Zed Head said:

Pretty sure that you saw a pressure drop with vacuum in your earlier tests.

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.

Edited April 13, 2019 by mbz

[S30Driver]

Where is the Captain when you need him.....  Probably out somewhere in Philly enjoying a steak and some micro brews .... 

[S30Driver]

mbz , I don't want to influence you unnecessarily to spend money, but a cheap vacuum gauge is a good investment.  It will tell you a lot about the shape of your L6 motor.

[mbz]

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

I think their vacuum gauge is like $15 bux, then 20% off.

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

I'm going to go sulk and watch Barret-Jackson replay from earlier today.

Edited April 13, 2019 by mbz

[Dave WM]

hard to imagine that you have zero vacuum at the manifold but its starting to look that way. Did you ever look into the EGR valve to make sure it was closing?

[mbz]

Just now, Dave WM said:

Did you ever look into the EGR valve to make sure it was closing?

Not yet, however that will be on the list for diagnostics tomorrow morning.

I'm reading up on the EGR valve tests in the manual now.