Checking the fuel pump V393 or fuel pump 2 V277 (Inline EKP) CFFA, CFFB — VW

Checking the fuel pump
V393
or
fuel pump 2
V277
(Inline EKP) CFFA, CFFB
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 diagnosis tester
Connecting nipple
VAS 6551/5-1
Hose
VAS 6551/2
Hose
VAS 6551/5-2
Pressure tester (diesel)
VAS 6551
Test prerequisite:
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.
First check that connector is fitted securely by pulling connector without pressing locking mechanism.
Note
The vehicle must be fuelled with the diesel fuel appropriate for the time of the year. The fuel sold in summer is filterable up to 0° C; that sold in transition time is filterable up to -10° C and that sold in winter is filterable up to -20° C. Summer fuel may coagulate (flock) in very low winter temperatures. If you are unsure, try and expose it to the low outside temperature for approximately 1 hour. If the fuel coagulates up to -20° C, it is unsuitable for low temperatures. This coagulation can block the strainer in the fuel delivery unit as well as the fuel filter.
WARNING
Fuel supply line may be pressurised. 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 pulling hose off connection.
Remove engine cover
Rep. gr.
10
Engine cover; Removing and installing engine cover
.
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
between connection
»B«
of
pressure tester (diesel)
VAS 6551
and the high pressure pump. Secure on the high pressure pump with clamp.
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 diagnosis 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 gauge and fuel line for leaks.
Test pressure gauge 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
.
Note
Check fuel system for leaks.