
Fuel Injection Control System
DESCRIPTION
System description
Three types of fuel injection control are provided to accommodate engine operating conditions; normal
control, idle control and start control. The ECM determines the appropriate fuel injection control. Under each
control, the amount of fuel injected is compensated to improve engine performance.
Pulse signals are exchanged between ECM and electronic control fuel injection pump (control unit is built-
in). The fuel injection pump control unit performs duty control on the spill valve (built into the fuel injection
pump) according to the input signals to compensate the amount of fuel injected to the preset value.
Start control
Input/output signal chart
Sensor Input Signal to ECM ECM Function Actuator
Engine coolant temperature sensor Engine coolant temperature
Fuel injection con-
trol (start control)Electronic control fuel injec-
tion pump Crankshaft position sensor (TDC) Engine speed
Ignition switch Start signal
When the ECM receives a start signal from the ignition switch,
the ECM adapts the fuel injection system for the start control.
The amount of fuel injected at engine starting is a preset program
value in the ECM. The program is determined by the engine
speed and engine coolant temperature.
For better startability under cool engine conditions, the lower the
coolant temperature becomes, the greater the amount of fuel
injected. The ECM ends the start control when the engine speed
reaches the specific value, and shifts the control to the normal
or idle control.
Idle control
Input/output signal chart
Sensor Input Signal to ECM ECM Function Actuator
Engine coolant temperature sensor Engine coolant temperature
Fuel injection con-
trol (Idle control)Electronic control fuel injec-
tion pump Crankshaft position sensor (TDC) Engine speed
Park/Neutral position (PNP) switch Gear position
Battery Battery voltage
Accelerator position switch Idle position
Vehicle speed sensor Vehicle speed
Air conditioner switch Air conditioner signal
Heat up switch Heat up switch signal
When the ECM determines that the engine speed is at idle, the fuel injection system is adapted for the idle
control. The ECM regulates the amount of fuel injected corresponding to changes in load applied to the
engine to keep engine speed constant. The ECM also provides the system with a fast idle control in response
to the engine coolant temperature and heat up switch signal.
SEF648S
ENGINE AND EMISSION BASIC CONTROL SYSTEM
DESCRIPTIONZD30DDTi
EC-1019

Supplemental Restraint System (SRS) ªAIR
BAGº and ªSEAT BELT PRE-TENSIONERº
The Supplemental Restraint System such as ªAIR BAGº and ªSEAT BELT PRE-TENSIONERº used along
with a seat belt, helps to reduce the risk or severity of injury to the driver and front passenger for certain
types of collision. The SRS system composition which is available to NISSAN MODEL Y61 is as follows (The
composition varies according to the destination and optional equipment.):
+For a frontal collision
The Supplemental Restraint System consists of driver air bag module (located in the center of the
steering wheel), front passenger air bag module (located on the instrument panel on passenger side),
seat belt pre-tensioners, a diagnosis sensor unit, warning lamp, wiring harness and spiral cable.
+For a side collision
The Supplemental Restraint System consists of front side air bag module (located in the outer side of
front seat), satellite sensor, diagnosis sensor unit (one of components of air bags for a frontal collision),
wiring harness, warning lamp (one of components of air bags for a frontal collision).
Information necessary to service the system safely is included in theRS sectionof this Service Manual.
WARNING:
+To avoid rendering the SRS inoperative, which could increase the risk of personal injury or death
in the event of a collision which would result in air bag inflation, all maintenance should be per-
formed by an authorized NISSAN dealer.
+Improper maintenance, including incorrect removal and installation of the SRS, can lead to per-
sonal injury caused by unintentional activation of the system. For removal of Spiral Cable and
Air Bag Module, see the RS section.
+Do not use electrical test equipment on any circuit related to the SRS unless instructed to in this
Service Manual. Spiral cable and wiring harnesses covered with yellow insulation tape either just
before the harness connectors or for the complete harness are related to the SRS.
Precautions for Fuel
DIESEL ENGINE*:
Diesel fuel of at least 50 cetane for ZD30DDTi engine
* If two types of diesel fuel are available, use summer or win-
ter fuel properly according to the following temperature con-
ditions.
+Above þ7ÉC (20ÉF) ... Summer type diesel fuel.
+Below þ7ÉC (20ÉF) ... Winter type diesel fuel.
CAUTION:
+Do not use home heating oil, gasoline, or other alternate
fuels in your diesel engine. The use of those can cause
engine damage.
+Do not use summer fuel at temperature below þ7ÉC
(20ÉF). The cold temperature will cause wax to form in
the fuel. As a result, it may prevent the engine from run-
ning smoothly.
+Do not add gasoline or other alternate fuels to diesel
fuel.
PRECAUTIONS AND PREPARATION
GI-1002

Pull the negative-pressure valve to open it. Check that it closes
completely when released.
CHECKING COOLING SYSTEM FOR LEAKS
Apply pressure to the cooling system with cap tester to check for
leakage.
Testing pressure:
98 kPa (0.98 bar, 1.0 kg/cm
2, 14 psi)
CAUTION:
Use of higher pressure than the specified value may cause
damage to radiator.
Checking and Replacing Fuel Filter and
Draining Water
Be careful not to spill fuel in engine compartment. Place a
rag to absorb fuel.
CHECKING FUEL FILTER
Check fuel filter for fuel leakage, damage and other abnormal
signs.
REPLACING FUEL FILTER
1. Disconnect harness connector and drain fuel.
2. Remove fuel filter using band-type filter wrench.
3. Remove fuel filter and fuel filter sensor.
CAUTION:
Remove fuel filter without spilling fuel. If spilt, wipe off
immediately. Be specially careful not to spill fuel on engine
mount insulator.
SMA871B
JMA109D
JMA110D
DMA011
SMA111D
ENGINE MAINTENANCEZD
Checking Cooling System (Cont'd)
MA-1017

4. Wipe clean fuel filter mounting surface on fuel filter bracket
and smear a little fuel on rubber seal of fuel filter.
5. Screw fuel filter on until a slight resistance is felt, then tighten
an additional more than 2/3 of a turn.
6. Install fuel filter sensor to new fuel filter. (Type A)
7. Bleed air from fuel filter.
Refer to ªAir Bleedingº in EC section.
8. Start engine and check for leaks.
DRAINING WATER
1. Drain water as follows.
Type A
Loosen drain cock and drain water.
Loosening drain cock four to five turns causes water to start
draining. Do not remove drain cock by loosening it exces-
sively.
If water does not drain properly, move the priming pump up and
down.
Type B
Loosen air bleeder screw from the sedimentor cover and then
loosen drain cock and drain water.
Loosening drain cock four to five turns causes water to start
draining. Do not remove drain cock by loosening it exces-
sively.
2. Bleed air.
Refer to ªAir Bleedingº in EC section.
Checking Fuel Lines
Check fuel lines and tank for proper attachment, leaks, cracks,
damage, loose connections, chafing and deterioration.
CAUTION:
Keep clean parts with compressed air when assembling.
SMA010
SMA825B
SMA281C
SMA803A
ENGINE MAINTENANCEZD
Checking and Replacing Fuel Filter and
Draining Water (Cont'd)
MA-1018