2001 Volkswagen Passat Cold Start Challenge

PLAYMAKER607

MEMBER
2001 VOLKSWAGEN PASSAT
6 CYL
2WD
AUTOMATIC
149,000 MILES

For the last two mornings, I am having problems with the first start in the morning. Engine and starter seem fine, but it's as if there is no fuel getting to injectors. After 4-6 trys at starting the engine, its as if the fuel starts to slowly trickle in, but not to all cylinders. After a couple more trys at turning the engine over, I'm able to keep the engine going with help from foot on accelerator until engine seems to be operating on all cylinders. After a total of 10 minutes or so, I'm off to work.

The rest of the day, I don't have any problems starting the car at all. Absolutely starts in two seconds.

So, seeing as I don't want to keep wearing down my starter, what's the real cause of this problem? Any thoughts?

Thanks in advance.

1 Reply

DAVE H

MECHANIC
13,383 POSTS

Hello .. thanks for the donation .. much appreciated

Sounds like the fuel pressure is dropping overnight ... check fuel pressure before cranking and after vehicle has been run !

Checking fuel delivery
Test requirements
Voltage supply OK
VAG1348/3A remote control connected
Test sequence
Remove fuel filler cap from fuel filler tube.
Remove intake manifold cover.
Open threaded connection (arrow) and catch exiting fuel using a rag.
Fig. 25: Opening Threaded Connection (Arrow) And Catch Exiting Fuel
Courtesy of VOLKSWAGEN OF AMERICA, INC.
WARNING:The fuel or fuel lines in fuel system can become very hot (danger of scalding)!
In addition, the fuel system is under pressure!Before opening the system, place rags around the connection area and release pressure by carefully loosening the connection!
Wear protective goggles and protective gloves when working on the fuel system!

Connect VAG1318 pressure gauge to fuel supply line using VAG1318/12 adapter.
Fig. 26: Connecting Vag1318 Pressure Gauge To Fuel Supply Line Using Vag1318/12 Adapter
Courtesy of VOLKSWAGEN OF AMERICA, INC.
Connect hose (VAG1318/1) to adapter (VAG1318/11) of pressure gauge and hold into measuring container.
Open shut-off valve of pressure gauge. Lever will point in direction of flow -A-.
Operate remote control and, while doing so, slowly close shut-off valve until pressure gauge displays 3 bar positive pressure. Do not change position of shut - off valve any more.
Empty the measuring container.
Delivery rate of Fuel Pump (FP) is dependent on battery voltage. Therefore, connect multimeter to vehicle battery using adapter cables.
Operate remote control
30 seconds long and measure battery voltage.
Compare fuel quantity pumped with specified value.
Fig. 27: Fuel Pump Delivery Versus Fuel Pump Voltage Graph
Courtesy of VOLKSWAGEN OF AMERICA, INC.
*) Minimum delivery rate cm 3 /30 s
**) Voltage at fuel pump with engine off and pump running (approx. 2 volts less than battery voltage).
Read-out example:
During test, a voltage of 12.2 volts is measured at battery. Since the voltage at the pump is approx. 2 volts less than battery voltage, there is a minimum delivery rate of 550 cm 3 /30 s.
If minimum delivery quantity is not obtained:
Check fuel lines for possible restrictions (kinks) or clogging.
Disconnect supply line -1- from fuel filter input.
Fig. 28: Disconnecting Supply Line From Fuel Filter Input
Courtesy of VOLKSWAGEN OF AMERICA, INC.
Connect VAG1318 pressure gauge to hose using VAG1318/10 adapter.
Repeat test of delivery quantity.
If minimum delivery quantity is now obtained:
Replace fuel filter.
If minimum delivery quantity is still not obtained:
Remove Fuel Pump (FP) unit (see FUEL PUMP, REMOVING AND INSTALLING ) and check filter strainer for dirt.
Only if no malfunctions have been found yet:
Fuel Pump (FP) faulty, replace Fuel Pump (FP) unit, see FUEL PUMP, REMOVING AND INSTALLING .
Erase DTC memory of Engine Control Module (ECM), see DIAGNOSTIC MODE 4: RESET/ERASE DIAGNOSTIC DATA .
Generate readiness code, see READINESS CODE, GENERATING .
Delivery rate has been obtained, but malfunctions are still suspected in the fuel supply (e.g. sporadic loss of fuel supply):
Check Fuel Pump (FP) current draw as follows:
Reconnect all disconnected fuel lines.
Remove luggage compartment floor cover.
Connect VAG1715 multimeter with current probe to green/yellow wire from wiring harness.
Fig. 29: Connecting Vag1715 Multimeter With Current Probe To Green/Yellow Wire From Wiring Harness
Courtesy of VOLKSWAGEN OF AMERICA, INC.
Start engine and let run at idle.
Measure Fuel Pump (FP) current draw.
Specified value: max: 8 amperes
NOTE:If malfunction in fuel system is sporadic, test can also be performed during a road test, but a second person is required.

If current draw is exceeded:
Fuel Pump (FP) faulty, replace Fuel Pump (FP) unit, see FUEL PUMP, REMOVING AND INSTALLING .
Erase DTC memory of Engine Control Module (ECM), see DIAGNOSTIC MODE 4: RESET/ERASE DIAGNOSTIC DATA .

Hope this helps