ViktorG.

Hi
I have an engine problem, i start the engine and it runs for about 20-30sek and then stops. if i take it to 3500-4000rpm the engine runs and i can drive the car but if i get below 3500 the engine stops.
there are no trouble codes.
And i have a Durametric porsche tester.

Any ideas?

Thanks Viktor.

XR4Tim

I would suspect the main fuel pump. The auxiliary pump kicks on at startup, and at full throttle. So when your Cayenne is running, it's because the auxiliary fuel pump is on. The main fuel pump is on the left side if I remember correctly.

deilenberger

You can test the pumps by alternately pulling the fuses and starting the car. The one that keeps running when it's fuse is installed is the good one.. the bad one is the one with the fuse removed.

BTW - the pump run sequence isn't quite that simple. There are also conditions where both will run (below 1/4 tank of fuel IIRC)..

XR4Tim

Yes, pump 2 comes on if there are less than 2.5 gallons of fuel in the tank as well.