Cayenne Turbo '03 no fuel to engine

[Porkyman]

Hope someone out in the Porsche world can help me! I have owned my Cayenne for the last 5 years, and it has provided stunning service, at 10 years old its low mileage at 60k miles!

The other day it decided to just 'run out of power'. I was in the middle of no where in Scotland (stunning roads!) and had to be towed home 100+ miles! The technical issue is:

Nearly full tank of fuel,

You can hear the right pump prime the system (then shut off), then you can start and run for 10 seconds, running out of fuel spluttering -- no engine management codes

Have been under the rear seats and opened the tank, tested both the pumps fine (direct to 12V source) and pump fine.

Fuses 13 and 14 are both fine, but havent tested the relays (but right relay should be OK since that pump primes the system).

If you start the car with say right pump 'hot wired' to a direct 12v source then engine run fine.

So it appears that the 'brain' isn't running the pump(s) to fuel the engine.

Has anyone any ideas on any other sensors that the 'brain' might be looking for input from to switch the pump(s) on?????? Anything on the high pressure side, or cam/crank sensors.

Thanks in advance for any help/pointers.

Cheers, Peter

[Porkyman]

An update of my findings, and some help/information needed please!

Tank is just over 1/2 full of fuel.

Both pumps tested in the car, measure approx 0.6 ohm resistance and pump well from a direct 12V supply.

Right pump primes the car, and will run the car for approx 10 seconds. Left pump doesn't come on at all.

Testing fuses 13 and 14 they are fine, along with the relays. However the feed wire from relay 1/6 in E-Box is approx 6000 ohm resistance! So with high voltage drop at the pump end then left pump will not power up!!!

If you remove relay 1/6 then the right pump works, and the car will run fine (tested to high speed with turbo boost). So the vehicle will work OK on one pump, with a good load on the engine.

So the QUESTION. Does anyone have details about the Cayenne wiring loom and specifically the routing of the RED/YELLOW feed to left pump? Are there any connectors between E-Box and the fuel tank?

Thanks in advance for any help.

+++++

FYI Found this information re pump sequences that has been helpful:

Starting procedure: left and right pumps onFuel tank qty >60 Lright pump on.High load: left and right pumps on.Fuel tank qty < 60 Lleft pump on.High load: left and right pumps on

[RFM]

Take a look at the bottom of the car, at the level of the left hand rear wheel, you should find two electrical connectors. There is often one ore more of the wires been overheated, repair this problem and find the cause. Usualy too heavy consuming power fuel pump(s), starting jamming, are the culprit.