Source: Chrysler Master Tech Issue 2 Reference Book -
dated February 1998
The fuel injectors are located under the cylinder head cover between
the rocker levers (Fig 16), and are secured with a hold-down clamp, cap
screw, and shoulder bolt. The shoulder bolt should
not be loosened when an injector is removed.
The fuel injectors operate at 4500 psi pop-off pressure, which is a significant
increase over the 3600 psi pop-off of 12 valve engine injectors.
Fuel is routed through the high pressure fuel line, inside the head, and
through connector tubes to the sides of the injectors.
A new fuel return rifle is bored into the cylinder head to return excess
fuel from the injectors to the fuel tank.
A new O-ring seal on the injector body (Fig 17) keeps engine oil out of
the injector and fuel out of the oil.
A single 1.5 mm copper gasket is used between the injector and head. The
copper gasket should be replaced each time an injector is removed and replaced.
The 24 valve injectors are not serviceable and are not
interchangeable with other injectors.
Centered injection (Fig 18) is used to produce a more even fuel pattern
on the top of the piston. This helps equalize the
temperature on the piston rings, reduces oil consumption, reduces nitrogen
oxide emissions, and permits elimination of the catalytic converter and
EGR to meet emissions standards.
Fuel Injection Pump
The VP44 Bosch Electronic injection pump (Fig 19) replaces the P7100 inline
As before, a gear train drives
the injection pump at 1/2 engine speed.
The pump is mounted in a fixed position through
an offset key (Fig 20). The key is numbered and must match the three-digit
number on each pump. Previous injector pump keys, when used, were not specific.
An arrow stamped into the top of the key must face
the pump. A DTC may be set if the key is installed backwards.
When installing a pump, always have the key at the
12:00 position to prevent the key from falling into the gear train (Fig
There are no adjustments to make to the pump drive
(i.e. no timing adjustment).
The injector pump is not serviceable, it must be
completely replaced as an assembly.
The injector pump is a high pressure radial piston
design and uses two solenoids to determine the timing and amount of fuel
that is injected.