Checking fuel system pressurisation pump G6 (electrical test) - vehicles with 6-cylinder or 8-cylinder engine — AUDI

Checking
fuel system pressurisation pump
G6
(electrical test) - vehicles with 6-cylinder or 8-cylinder engine
Special tools and workshop equipment required
Remote control
V.A.G 1348/3A
for V.A.G 1348 with
adapter cable
V.A.G 1348/3-2
Hand-held multimeter
V.A.G 1526C
Auxiliary measuring set
V.A.G 1594C
Vehicle diagnostic, testing and information system
VAS 5051B
with
trigger clamp, 100 A
VAS 5051B/7
Procedure
Note
Fuel is drawn out of the fuel tank baffle housing by the high-pressure pump of the diesel direct-injection system. The
fuel system pressurisation pump
G6
serves only to operate the suction-jet pumps.
Proceed as follows:
Observe test conditions
Chapter
.
Ignition off.
Checking voltage supply
Take out floor covering in front right footwell.
Remove knurled screw
1
.
Pull trim
2
to rear out of fastener
3
and detach.
Pull out fuse in fuse holder
S1
from fuse carrier (blue)
ST4
.
Connect remote control
V.A.G 1348/3A
with
adapter cable
V.A.G 1348/3-2
to bottom terminal of socket of fuse in fuse holder
S1
arrow 1
.
Connect crocodile clamp to battery
“+”
, e.g. to socket of 60 A fuse at top of fuse box
arrow 2
.
Press remote control switch.
Pump should start running audibly.
Note
The fuel pump runs very quietly. Where possible, avoid noisy surroundings when testing the fuel pump (otherwise a second mechanic is required).
If no noise can be heard from the pump, remove bolts
arrows
on right under floor trim in luggage compartment and detach cover.
Release and unplug electrical connector
arrow
.
Connect
hand-held multimeter
V.A.G 1526C
between contacts
1
and
4
to measure voltage.
Press remote control switch.
Specification: approx. battery voltage.
If reading does not match specification, check wiring connection and repair
Current flow diagrams, Electrical fault finding and Fitting locations
.
If reading matches specification although no noise can be heard from pump, remove fuel delivery unit
Chapter
.
Check connections and continuity of electrical wiring between flange and fuel pump.
If no wiring fault is detected: fuel pump is defective. Renew fuel delivery unit
Chapter
.
Checking current draw
Fuel pump voltage supply OK
Anchor
.
Remote control
V.A.G 1348/3A
with
adapter cable
V.A.G 1348/3-2
connected to bottom terminal of socket of fuse in fuse holder
S1
arrow 1
.
Connect crocodile clamp to battery
“+”
, e.g. to socket of 60 A fuse at top of fuse box
arrow 2
.
Connect
vehicle diagnostic, testing and information system
VAS 5051B
with
trigger clamp, 100 A
VAS 5051B/7
to wiring of remote control as shown in illustration.
Press remote control switch and read off current draw of
fuel system pressurisation pump
G6
.
Specification: 4 ... 6 A.
If specification is not attained, identify fault as follows:
Readout
Cause of fault
Fault rectification
approx. 2 A
Tank empty
Fill tank
Fuel delivery unit installed incorrectly
Check proper installation of fuel delivery unit
Anchor
Baffle housing leaking
Check baffle housing for leaks
Chapter
Fuel gauge sender 2
G169
installed incorrectly
Check proper installation of
fuel gauge sender 2
G169
Chapter
0 A
Electrical wire defective
Repair
Fuel system pressurisation pump
G6
defective
Renew fuel delivery unit
Note
A current draw of 2 A indicates that the fuel pump is running dry because there is no fuel in the baffle housing.
To verify test result, put 1 ltr. of diesel into fuel tank and repeat measurement. If a current draw of 6 A is now indicated, the fuel pump is OK.