I think you guys are right about all this. Just found this (c/o VWvortex):
Diagram of fuel system:
http://monty.syr.edu/vw/20vforum/AWDVacDiag.gifThe Key to the diagram is system is found on this link (but also pasted it for convenience):
http://forums.vwvortex.com/zerothread?id=2666114Key:
1 - Vent line
From gravity valve at fuel tank See "Fuel Tank, Removing and Installing" item no 8. See: Fuel Tank\Service and Repair
2 - EVAP canister
With Evaporative Emission (EVAP) canister purge regulator valve -N80-
3 - Turbocharger
4 - Check-valve
For EVAP canister system
5 - Pressure unit
For Boost Pressure Regulation Valve
6 - Deceleration shut-off valve
7 - Wastegate bypass regulator valve - N75
Valve is activated (pulsed) by the Engine Control Module (ECM)
Checking activation: See Output Diagnostic Test Mode (DTM), activating. Refer to "On Board Diagnostic". See: Computers and Control Systems\Testing and Inspection
8 - Brake booster
9 - Check-valve
For brake booster
10 - Air filter with Mass Air Flow (MAF) sensor - G70 -
11 - Pressure control valve for crankshaft housing ventilation
12 - Combination valve
For Secondary Air Injection (AIR) system
Checking. See: Emission Control Systems\Air Injection\Testing and Inspection
13 - Fuel pressure regulator
14 - Check-valve
15 - Recirculating valve for turbocharger -N249-
16 - Secondary Air Injection (AIR) solenoid valve -N112-
Checking. See: Emission Control Systems\Air Injection\Testing and Inspection
17 - Crankcase ventilation
18 - Check-valve
For EVAP canister system
19 - Charge air pressure sensor -G31- / charge air cooler
20 - Secondary Air Injection (AIR) pump motor - V101 - *
Checking function. See: Emission Control Systems\Air Injection Pump\Testing and Inspection
21 - Vacuum reservoir
The suspects are number 1 and number 2!
