Fuel Pump, Checking
A - If minimum delivery rate is not attained after checking as described in the Repair Manual, continue checking as follows:- Check the fuel lines for possible restrictions (kinks) or blockages, repair or replace as necessary
Pull the fuel supply line -1- off inlet to fuel filter
- Connect pressure gauge VAG 1318 to fuel line using adapter 1318/10.
- Repeat delivery rate check
If the minimum delivery rate is still not attained
- Replace the fuel filter
If the minimum delivery rate is still not attained
- Remove the fuel delivery unit and check the strainer filter for contamination
If at this point no malfunction has been detected
- Replace the fuel delivery unit
B - If the delivery rate has been attained but nevertheless you suspect a fuel supply system malfunction (e.g. intermittent failure of fuel supply system):
- Check the amperage draw of the fuel pump as follows
- Reconnect all disconnected fuel lines
- Connect the Fluke 83 multimeter (or equivalent) to the red/yellow wire from wiring harness using the Fluke amperage measurement adaptor
- Start the engine and let idle
- Measure the current draw of the fuel pump.
Specification: 8 amps maximum
Note:
If the fuel system malfunction is intermittent, you can perform the check during a test drive, using a second technician.
If the amperage draw is exceeded
- Replace the fuel delivery unit
Special tools, testers and auxiliary items
^ Hand vacuum pump US 8026
Test conditions
^ Ignition switched off
Test sequence
- Remove Air Cleaner, Repair Group 24
Vehicles --> 07.95 (blue valve)
- Remove purge hose -1- from EVAP canister purge regulator valve -6- at throttle body -2- and install hand vacuum pump US 8026 to hose.
Vehicles --> 08.95 (black valve, OBDII)
- Remove purge hose from EVAP canister -4- at purge regulator valve -6- and install hand vacuum pump US 8026 to hose.
All Vehicles -->
- Disconnect breather hose -3- (from fuel tank) at EVAP canister -4- and plug port on canister.
- Operate hand vacuum pump US 8026 several times
^ Vacuum must not build
If vacuum builds-up
- Check breather connection -5- on EVAP canister -4- for contamination, clean as necessary
- Remove plug from canister port
- Check EVAP canister purge regulator valve -6- for continuity, replace if necessary (Vehicles --> 07.95 blue valve only)
If vacuum does not build-up
- Remove fuel filler cap
- Connect hand vacuum pump US 8026 to breather hose -3- from fuel tank (previously removed from EVAP canister -4-)
- Operate hand vacuum pump US 8026 several times
^ Vacuum must not build up
If vacuum builds-up
- Check gravity valve Page 20-5, item 28
- Check line -3- (from fuel tank) for blockage
If vacuum does not build-up
- Re-install fuel filler cap
- Operate hand vacuum pump US 8026 several times
^ Vacuum must not build up
Note
If the fuel level is low, it will take much longer to build a vacuum, the vacuum pump must be operated at least 20... 30 times.
If vacuum builds-up
- Replace fuel tank cap