Be Aware! Vacuum Triangle "Of Death" New but not functional causing lean condition

[Classic11]

Hello all,
this is just to make everybody aware of what I experienced and I hope it will save some people a lot of headache. I just finished a 3.2 build, all stock for a customer. One of the items to replace if still original is the small black rubber triangle "Triangle of Death" that directs vacuum to the fuel pressure regulator and damper, which I did.
When checking fuel pressure I realized it did not go to 2.5 bar as expected and started investigating. It turns out that the new part (not purchased from Pelican) has a passage inside that was not formed correctly and therefore did not direct vacuum to the regulator as it supposed to. Crazy enough, I ordered 2 and put the 2nd one on my personal 911 and when investigating it, same problem. Please check them when you get new ones or check the one you previously installed. This one came from a German manufacturer, they don't make just a few at a time, so likely many bad ones out there. This can cause a very lean condition in high RPM's and pairing this to a hot day can lead to some series problem. See here the picture.

Daniel

[Missed Approach]

Hi Classic11- Good info, but to confirm- are you referring to Porsche Vacuum Line Connector - 92857372702?

https://www.pelicanparts.com/More_Info/92857372702.htm?pn=928-573-727-02-OEM

Shown as Part #21 in the diagram?



Cooking on a Porsche 911- The herbal butter made the difference.
https://www.youtube.com/watch?v=FvXBR50rH9E

[Classic11]

Hello @Missed Approach, yes you are correct. I probably should have added a picture of it before i cut it apart.

[T77911S]

i had the same issue on a 77s fuel injector line. (plastic ones). reduced fuel flow to one injector causing detonation above 4k. it was not formed correctly inside. i cut it open like you did.
two PO's did not find it. it took me a long time to find it. like over a year. almost replaced the FD but i kept looking. the car was bought cheap because of this.

[GH85Carrera]

When I took my engine out, I replaced every single vacuum line and connector as a routine. They were all old, and several had cracks. I also replaced the fuel lines. It was not very expensive, and just the perfect time to do it all. I would recommend replacing all the connectors if they are still there after 35+ years.

[Tremelune]

Pedantic heads-up: When people talk about the "triangle of death" on an air-cooled 911, they mean the breather cover, thermostat, and oil pressure send underneath the airbox that are notorious for leaking oil.

Dunno what that black thing is, but thanks for the info!

[porschyard]

Daniel, not sure if you are correctly understanding the correlation between the fuel pressure and the vacuum supplied via the rubber tee. The fuel pressure W/O vacuum should be 2.5 bar and drop to 2 bar when vacuum is present. Vacuum at the throttle valve port for the pressure regulator and damper will only be present at idle or decell. with the throttle closed.

When the throttle is opened vacuum is lost to the FPR and the pressure increases to 2.5 bar. The issue with the tee having a blocked port would have no effect on the fuel mixture being lean and actually would cause a rich mixture at idle due to the higher fuel pressure.

You don't mention if you are checking fuel pressure with the engine running or jumping the pump with the engine off but either way if you are not reaching 2.5 bar W/O vacuum to the FPR something else is going on. What was the fuel pressure you measured with the blocked tee ?

Richard