Checking supplementary fuel pump V393 or fuel pump 2 V277 (in-line electronic fuel pump) — VW

Checking
supplementary fuel pump
V393
or
fuel pump 2
V277
(in-line electronic fuel pump)
Note
The component designation for the inline electronic fuel pump was changed from
“supplementary pump V393”
to
“fuel pump 2 V277”
in a software revision. This is the same component.
Special tools and workshop equipment required
Vehicle diagnostic tester
Connecting nipple
VAS 6551/5-1
Hose
VAS 6551/2
Hose
VAS 6551/5-2
Pressure tester (diesel)
VAS 6551
Test prerequisite:
Observe type of fuel system
Chapter
.
Fuses must be OK.
Connect battery charger to ensure sufficient voltage supply of min. 12.5 V.
Minimum filling level of fuel tank: 15 l.
Ensure that vehicle is placed on a level surface.
Ensure that fuel hoses and lines in engine compartment and on underbody are not closed through damage (kinks).
All electrical consumers, e.g. lights and rear window heating, must be switched off.
Note
The vehicle must be fuelled with the diesel fuel appropriate for the time of the year. The fuel sold in summer is filterable down to 0°C; that sold in transition time (spring and autumn) is filterable down to -10°C and that sold in winter is filterable down to -20°C. Summer diesel may coagulate (flock) at very low winter temperatures. If you are unsure what type of fuel is at hand, expose a sample to the low outside temperature for approximately 1 hour. If the diesel fuel coagulates (flocks) at temperatures down to -20°C, it is unsuitable for low temperatures. This coagulation (flocking) can block the strainer in the fuel delivery unit as well as the fuel filter.
WARNING
The fuel line is under pressure.
Risk of injury to eyes and skin from fuel.
Wear eye protection and protective clothing to avoid eye injuries and skin contact. Before loosening hose connections, wrap a cloth around the connection. Then release pressure by carefully opening the connection point.
Remove engine cover panel
Rep. gr.
10
Engine cover panel; Removing and installing engine cover panel
.
Open clamp and pull fuel supply line
arrow
off the high-pressure pump.
Place
connecting nipple
VAS 6551/5-1
in supply line and secure with clamp.
Connect
hose
VAS 6551/2
between
connecting nipple
VAS 6551/5-1
and connection point
»A«
of
pressure tester (diesel)
VAS 6551
.
Connect
hose
VAS 6551/5-2
to connection point
»B«
of
pressure tester (diesel)
VAS 6551
and high-pressure pump. Secure to high-pressure pump with a clip.
Switch on
pressure tester
VAS 6551
by pressing
On/Off
button.
Open shut-off taps
“A”
and
“B”
of
pressure tester
VAS 6551
and close shut-off tap
“C”
.
Connect
vehicle diagnostic tester
and then carry out
“Guided Fault Finding, Checking electrical fuel pump(s)”
.
Note
The fuel pump is now activated for 30 seconds.
Specification: at least 3.5 bar
If the specification is not attained:
Check connections between pressure tester and fuel line for leaks.
Check pressure tester for leaks.
Check fuel lines and their connections for leaks.
Check whether fuel filter is blocked.
Check fuel delivery rate of
fuel system pressurisation pump
G6
Chapter
.