DESCRIPTION & OPERATION
Page 15
The EUP design does not include a helix on the
pump plunger. Fuel delivery is controlled entirely
by the solenoid valve. To start fuel delivery, the
V-MAC III control system allows current to flow to
the solenoid, closing the solenoid valve and
trapping fuel in the pump. As the plunger moves
upward, fuel is delivered through the high-
pressure line to the fuel-injector nozzle assembly.
When current flow to the solenoid is stopped, the
solenoid valve opens and fuel in the pump then
flows to the cylinder block fuel return gallery.
Refer to Figure 5.
5
Figure 5 — Electronic Unit Pump
Current production E-Tech™ engines contain
EUPs with three O-rings. On future production
engines the center O-ring will be eliminated.
Present EUP service kits available through
MACK service parts do not contain the center
(brown) O-ring.
The EUP system, using proven industry
technology, is well adapted to troubleshooting.
When required, an individual EUP can be
replaced with a minimum of downtime.
Because the unit pumps are located in close
proximity to the exhaust manifold, heat shields
have been added to prevent excessive heat from
reaching the EUP components.
The right-side heat shields on an E-Tech™
engine are a mandatory part of the engine
(Figure 6). The heat shields must be reinstalled if
they are removed for maintenance or repair.
Failure to do so will result in damage to the
sensitive electronic components.
6
Figure 6 — Heat Shields (with Right-Side Mounted
EECU)
1. Heat Shield Attachment Points
5_106_00.bk Page 15 Friday, August 4, 2000 11:17 AM
BDC for engine manuals and specs
