CHECK FOR
DAMAGE
FEBI explains the importance of
regularly inspecting high-pressure
fuel pump cam followers to protect
against consequential damage.
VAG has been using fuel stratified injection (FSi) to power their petrol
engines since 2000. This system was designed with the aim to improve
fuel consumption and engine efficiency. By running the engine with
leaner fuel mixtures, emissions are lowered. As with any components
that operate in extreme conditions, fuel pumps are susceptible to wear
and tear. Thus, it is advised to regularly inspect high-pressure fuel
pump cam followers.
An example of a VAG 1.8 litre
four cylinder FSI engine
10 years and has since been superseded by a single cylinder pump with
a roller on the end of the piston to reduce friction.
Symptoms of cam follower wear:
• Increased engine noise
• Loss of engine power
• Illumination of engine management lamp
• Fault codes logged by engine management as a result of mechanical fault
relating to fuel pressure loss and poor regulation
A
B
C
POSITION OF POWER
Stratified fuel injectors are situated directly in the cylinder head so
that fuel can be directly injected into the combustion chamber at high
pressure to increase atomisation. The fuel cloud is sprayed relative to
the position of the spark plug, thus reducing areas of an incomplete
fuel-to-air mixture burn for increased efficiency.
What makes these engines unique is the high-pressure fuel system. It
comprises a high-pressure fuel pump (HPFP), fuel rail, high pressure
injectors, a pressure regulator and sensors to feed back fuel pressure
readings to the engine management.
Various stages of wear on cam follower. Note the case-hardened top on the brand new cam follower
(A), at 30,000 miles (B) and 70,000 miles (C). As mileage increases, scratch marks and oil staining
become more apparent on the sides.
If excessive cam lobe wear has occurred, the maximum pump piston lift
is limited. This causes fluctuation in fuel pressure. Cam lobe wear can
lead to deterioration in the base of the fuel pump cam follower, leading
to damage of the fuel pump piston base.
KEEPING AN EYE ON THINGS
THE WEAR OF HIGH PERFORMANCE
The pump’s piston is run off lobes on the camshaft with a bucket type
cam follower which is case-hardened to take the stresses between the
camshaft and the pump piston.
However, early cam followers had been reported to wear out quickly. In
the more serious cases, this led to damage of both the camshaft and fuel
pump. As a result, VAG released a technical service bulletin highlighting
an improved cam follower that was treated with better case-hardening
to prolong its service life. This pump design was in production for about
16 CAM FOLLOWERS
In conclusion, febi advises that the HPFP cam follower should be
inspected for wear periodically as it is better to replace the follower
before it has had the chance to cause pump and camshaft damage.
When choosing a replacement HPFP cam follower, one should consider
the material quality. febi’s HPFP cam follower (part no. 37162) is
fully precision engineered to OE specification to provide reliable
performance. Available from FPS via same/next-day delivery and
catalogued on the F:Drive and MAM Autocat, please speak to your local
FPS representative for more information.
VITAL NEWS ISSUE 50