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

[Dave WM]

you are just going to run a quick test, 2 gall should be fine.

[Dave WM]

the idea is do you still get those over 40 psi readings with the engine running.

[Dave WM]

fyi, the low pressure 30 psi engine off pump on makes no sense what so ever, I am throwing that aside for now.

[mbz]

24 minutes ago, Dave WM said:

Next test will be to remove the return line from the fuel rail and have it dump directly into a empty container.

Can I do this at the hose the connects to the metal return line by the fuel filter?

I ask because of the easy access it would be preferable.

[mbz]

10 minutes ago, Dave WM said:

the idea is do you still get those over 40 psi readings with the engine running.

So, to be clear, with the fuel return line disconnected and draining into a bucket, if the fuel pressure is still high (like 38-40 psi), then there is a clog somewhere in the fuel rail to the return line?

AND, if the fuel pressure is normal (36 psi), then it would indicate a clog in the metal fuel return lines that run under the car.

Is that right?

Edited March 31, 2019 by mbz

[Dave WM]

8 minutes ago, mbz said:

Can I do this at the hose the connects to the metal return line by the fuel filter?

I ask because of the easy access it would be preferable.

yes

[Dave WM]

3 minutes ago, mbz said:

So, to be clear, with the fuel return line disconnected and draining into a bucket, if the fuel pressure is still high (like 38-40 psi), then there is a clog somewhere in the fuel rail to the return line?

Is that right?

more likely a defect in the FPR. I have a video showing testing the FPR with compressed air. See my youtube channel Dave WM

[mbz]

1 minute ago, Dave WM said:

more likely a defect in the FPR. I have a video showing testing the FPR with compressed air. See my youtube channel Dave WM

AND, if the fuel pressure is normal (36 psi), then it would indicate a clog in the metal fuel return lines that run under the car.

Is that right?

[mbz]

2 minutes ago, mbz said:

I have a video showing testing the FPR with compressed air.

This video...?

 

[mbz]

Dave WM:

To be clear, with the fuel return line disconnected and draining into a bucket, if the fuel pressure is still high (like 38-40 psi), then there is a clog somewhere in the fuel rail to the return line? (most likely a failed FPR?)

AND, if the fuel pressure is normal (36 psi), then it would indicate a clog in the metal fuel return lines that run under the car.

Is that right?

 

Also regarding FPR test with compressed air, I do not have an air compressor. It would cost me less to just order the FPR and swap it out at this point. (providing it is the most likely culprit for the high fuel pressure)

Edited March 31, 2019 by mbz

[Dave WM]

I hate to recommend replacement  of parts unless you know for sure.. Your call on that one. But 1st things 1st try the return bucket test. I would also like to know the test gauge is working as it should. this would require some kind of comparison test with a known PSI source or a known working gauge.

and yes that is the video, you can see how the FPR begins to bleed at 36 psi.

 

Edited March 31, 2019 by Dave WM

[Dave WM]

33 minutes ago, mbz said:

AND, if the fuel pressure is normal (36 psi), then it would indicate a clog in the metal fuel return lines that run under the car.

Is that right?

yes that OR a plugged return line in the fuel tank. If the tank was coated with a liner like "red kote" and the lines were not blown clear with compressed air, I would be concerned with a clog (that is what the red kote is designed to do after all clog holes...)