Fleet Maintenance - 33

further by making modifications to increase
its performance.
According to Dave Needham, diesel product
engineering director at Delphi Technologies,
the company's F2 common rail system includes
low static injector leakage and dynamic leakage
features. The company is currently working to
develop the F3 generation that will feature a DFI
21 injector. The DFI 21 injector will be fitted with
a 1mm diameter nozzle control valve to reduce
leakage and allow for higher injection pressures.
The F3 system will also offer embedded closedloop control electronics that will monitor the
operation of each injector and adjust performance in real-time.
Volvo Trucks' common rail system is completely
contained under the valve cover and consists of
three pumping and three non-pumping injectors,
says John Moore, product marketing manager at
heavy duty original equipment manufacturer
Volvo Trucks North America. The three pumping injectors are directly connected to a rocker
arm that rides a double lobe cam, allowing for two
pumping sequences for each injector during every
full rotation of the camshaft.
This design not only optimizes the efficiency
of the pumping injectors due to less surface area
on pumping surfaces but also lowers the clamping load on the injector from the rocker. Pumping
twice per revolution of the cam enables a smaller
»Delphi Technologies is currently working to
develop its F3 common rail system that will
offer embedded closed-loop control electronics
that will monitor the operation of each injector
and adjust performance in real-time.

»Volvo Trucks' D13 engine features
a common rail fuel injection that is
completely contained under the valve
cover and consists of three pumping
and three non-pumping injectors.
Photo courtesy of Volvo Trucks North America

Determining when
there's an issue

diameter pumping piston to be used to generate a
maximum rail pressure of 35,000 psi. It also delivers the volume of fuel necessary under a full load.
The smaller piston diameter requires less force
from the rockers to generate the same pressure
required for a larger diameter piston.
Volvo's common rail system also reduces weight
by not running high-pressure lines up the side of
the block from a transfer pump to the common
rail. The pumping injectors are directly connected to the rail and can directly inject fuel into the
cylinder with the fuel under pressure from the
common rail.

There are several different ways to verify whether there is an issue with the fuel
injection system, some more visual than
others. One such way is to track fuel economy.
Fleets that monitor each of their vehicle's fuel
consumption and mileage will notice when there
is a fluctuation in fuel economy.
"Say you have a fuel injector that is leaking or
delivering more fuel than it should be, you would
track that if you were tracking fuel economy," says
Mike Cleary, owner and ASE master heavy truck
technician of Cleary Automotive. Cleary also
manages and teaches courses for Automotive
Technical Support Services (ATSS), a training
organization offering technician training for
drivability and electronics diagnostics.
Another indicator of a fuel injection issue is
checking the air-fuel ratio by using a scan tool. If
the air-fuel ratio is running too rich or too lean -
 Continued Page 34

Photo courtesy of Delphi Technologies

"If there's an air-to-fuel ratio
problem, it's likely due to the
fuel not being delivered properly.
That's an indicator that there's
a problem with the injection."
Barry Hoyland, Owner, Vehicle Service Solutions of California (VSSCA)

April 2020 | VehicleServicePros.com

http://www.VehicleServicePros.com

Fleet Maintenance

Table of Contents for the Digital Edition of Fleet Maintenance