Posting after a long time.......Cayenne 955 V6 base 2006.
Driving normally and suddenly it kinda dies......I mean the RPMs drop. I bring it to a stop and then it idles from sometime and the RPMs drop to like 200 and it stalls.
I restart it......drives ok for sometime and then again it kinda dies. Has 3/4 of tank.
Cranks ok RPMs start dropping and it stalls.
So my friend who fixes my car is luckily traveling with me.
So he does a temporary fix......he takes the relay in the engine compartment next to Fuses 13 and 14 left side of engine bay and shorts it.....that makes the car run fine.
Any ideas to what the issues might be?
He checked the fuel pump and he can hear it running.

 

fuel level sensor? Had a similar issue in my old BMW X5 and ended up replacing the fuel pump, level sensor and associated bits to be sure. Was fine after that.

 

Sounds like primary fuel pump relay... or, even pump itself.

 

Also if it stands for sometime it runs fine for a few kms.....if it was the relay wouldnt it be stalling immeidatley?
Also why would shorting the relay make it work?

 

If you floor the car will it stay running? If so, could be your main fuel pump, there are two. I had similar symptoms when my main fuel pump went. Would start for a moment, reduce RPMs and stall. If I came close to giving it wide open throttle it would stay running. The second fuel pump is in use at start up (which is why the car starts), and in high throttle situations, which is why the car would stay running close to WOT.

The nice thing is if you remove the fuse for the main fuel pump, the car will stay running long enough for you to get it home to repair it (at least it did for me).

 

Removing fuse didnt do anything, shorting the relay worked and it ran and got us home.
it still drives ok for short distances.

 

If jumpering the fuel pump relay made the car run right, then that's likely the culprit. The more obscure thought I had is on the HVAC were you using the A/C? I believe there's a switch or circuit that when the A/C compressor comes on is supposed to raise the idle speed to prevent the extra load from the compressor from stalling the engine. If the stalling was occurring at the same time as the A/C compressor kicking on to cool the interior, that may be something else to check. A way to test this is to flip open the little door and push the ECON button. This turns off the Compressor but allows the fans and things to still work.

 

AC was on all the time......now last few days for short rides its not giving any trouble.......its only when it does abour 80-100kms that the problem comes in.

 

Sounds like the fuel pump relay may be overheating and then cutting out. See if that relay is the same as another one (like for the horn or something) and try swapping them.

 

yep tried that too but its not the relay.....my buddys gonna open the car up next few days will keep you guys posted.