1991 ACURA NSX fuel

Component Locations

Index
FUEL TANK EVAPORATIVE EMISSION(EVAP) VALVE
EVAPORATIVE EMISSION (EVAP) TWO WAY VALVE

Testing, page 11-157
FUEL PUMP

Troubleshooting, page 11-116
Testing, page 11-119

Replacement, page 11-119
FUEL FEED PIPE
FUEL FILTERReplacement, page 11-114
FUEL PRESSURE REGULATOR
Testing, page 11-113

Replacement, page 11-114

FUEL RETURN PIPE
FUEL INJECTORS

Troubleshooting, page 11-107
Replacement, page 11-110
FUEL PUMP RELAY

Troubleshooting, page 11-116
FUEL RAIL
FUEL TANK
Replacement, page 11-126

FUEL

VAPOR HOSE
EVAPORATIVE EMISSION
(EVAP) CONTORL CANISTER

Troubleshooting, page 11-154

FUEL FILL CAPProCarManuals.com

System Description
Vacuum Connections
CONTROL
BOX
page 11-7

THROTTLE
VALVE
DASHPOT
CHECK VALVE

EVAP

PURGE CONTROL
DIAPHRAGM VALVE
EVAP CONTROL
CANISTER
TO EVAP TWO-WAY

VALVE
FRONT OF
VEHICLE
THROTTLE VALVE
DASHPOT CONTROL

DIAPHRAGM

EGR VALVE
LIFT SENSOR
FUEL PRESSURE

REGULATOR

INTAKE

AIR

BYPASS

(IAB)

DIAPHRAGM
EGR VALVEProCarManuals.com

System Description
Vacuum Connections (cont'd)
FRONT HEATED OXYGEN SENSOR (HO2S)
REAR HEATED OXYGEN SENSOR (HO2S)
MANIFOLD ABSOLUTE PRESSURE (MAP) SENSORINTAKE AIR TEMPERATURE (IAT) SENSOR
FRONT KNOCK SENSOR (KS)
REAR KNOCK SENSOR (KS) IDLE AIR CONTROL (IAC) VALVE
FAST IDLE THERMO VALVE
AIR CLEANER (ACL) FUEL INJECTORFUEL PRESSURE REGULATOR
FUEL FILTER
FUEL PUMP (FP)
FUEL TANK
THROTTLE VALVE DASHPOT CONTROL DIAPHRAGM
THROTTLE VALVE DASHPOT CHECK VALVE INTAKE AIR BYPASS (IAB) CHECK VALVE
INTAKE AIR BYPASS (IAB) VACUUM TANK
INTAKE AIR BYPASS (IAB) CONTROL SOLENOID VALVE
INTAKE AIR BYPASS (IAB) CONTROL DIAPHRAGM
FRONT THREE WAY CATALYTIC CONVERTER (TWC)
REAR THREE WAY CATALYTIC CONVERTER (TWC)
POSITIVE CRANKCASE VENTILATION (PCV) VALVE
EXHAUST GAS RECIRCULATION (EGR) VALVE
EXHAUST GAS RECIRCULATION (EGR) VALVE LIFT SENSOR
EXHAUST GAS RECIRCULATION (EGR) VACUUM CONTROL VALVE
EXHAUST GAS RECIRCULATION (EGR) CONTROL SOLENOID VALVE
EVAPORATIVE EMISSION (EVAP) CONTROL CANISTER
EVAPORATIVE EMISSION (EVAP) PURGE CONTROL SOLENOID VALVE
EVAPORATIVE EMISSION (EVAP) PURGE CONTROL DIAPHRAGM VALVE
EVAPORATIVE EMISSION (EVAP) TWO WAY VALVEProCarManuals.com

System Description
Electrical Connections

FUSES
CLOCK (7.5 A)*

ACG
(120 A)**

ACG(S) (20 A)**

IG COIL (30 A)**

No. 2 (15 A)

No. 5 (10 A)
No.
4(15
A)

No. 7
(7.5
A)
In the under-hood
fuse/relay box In the engine
compartment
fuse/relay box

CKP/CYP

SENSOR

TO A/T
GEAR

POSITION
SWITCH

NEUTRAL

SWITCH
(M/T)

AUTO A/C

CONTROL

UNIT
CLUTCH
SWITCH
(M/T)
SERVICE

CHECK

CONNECTOR

A/C

PRESSURE

SWITCH A
A/C

PRESSURE

SWITCH B FUEL PUMP

RESISTORProCarManuals.com

System Description
System Connectors [Behind the seat back panels] (cont'd)
ENGINE
WIRE HARNESS

C476
C158
C478
C161

C475
C159 C154
(ECM-A)
C155 (ECM-B) C156 (ECM-C)

C480 (ECM-F)

C483

SIDE
WIRE
HARNESS

FUEL TANK
WIRE HARNESS
C482
C481
C157 (ECM-D)
C477
C160

FLOOR
WIRE HARNESS
ProCarManuals.com

System Description
System Connectors [Behind the seat back panels] (cont'd)
ENGINE
WIRE
HARNESS

C489
C771 C491

C496
C495

SIDE
WIRE HARNESS
C500
C527
C494
C493

FUEL TANK
WIRE HARNESS

C773

FLOOR
WIRE
HARNESS
ProCarManuals.com

PGM-FI
VARIABLE VALVE
TIMING & VALVE

LIFT ELECTRONIC CONTROL PRES- SURE SWITCH VEHICLE

SPEED

SENSOR IGNITION

TIMING

ADJUSTER
KNOCK

SENSOR
A/T FI

SIGNAL A
A/T Fl

SIGNAL B
IDLE AIR
CONTROL VALVE
OTHER

IDLE

CONTROLS
FUEL

INJECTOR
FUEL

METERING
OTHER

FUEL
SUPPLY INTAKE

AIR
EXHAUST

GAS

RECIRCU-
LATION

CONTROL
SYSTEM

EMISSION CONTROL

OTHER

EMISSION
CONT-

ROLS

11-141

11-145

11-127

11-104

11-116

11-54,11-56

11-107

11-84

11-88

11-82

11-82

11-80

11-78

11-76
6-17('91-'93)
IDLE CONTROL
FUEL SUPPLY
FUEL

PUMPProCarManuals.com

PGM-FI System

System Description

INPUTS
ENGINE CONTROL MODULE (ECM)

OUTPUTS

FRONT HO2S

REAR HO2S

MAP Sensor

CKP/CYP Sensor

ECT Sensor

TP Sensor

IAT Sensor

VSS

FRONT KS

REAR KS

Ignition Timing Adjuster

EGR Valve Lift Sensor

A/T Fl Signals

TCS Signals

Starter Signal

ALT FR Signal

Air Conditioning Signal

A/T Gear Position Switch Signal

Neutral Switch Signal (M/T)

Clutch Switch Signal (M/T)

VTEC Pressure Switch

Battery Voltage (IGN.1)

Fuel Pump Terminal Voltage
Fuel Injectors

PGM-FI Main Relay (Fuel Pump)

Malfunction Indicator Lamp

IAC Valve

A/C Compressor Clutch Relay

ICM

EVAP Purge Control Solenoid Valve

Fuel Pump Relay

EGR Control Solenoid Valve

IAB Control Solenoid Valve

Engine Compartment Fan Relay

VTEC Solenoid Valve

TCS Control Signals

FRONT HO2S HEATER

REAR HO2S HEATER

PGM-FI System

The PGM-FI system on this model is a sequential multiport fuel injection system.

Fuel Injector Timing and Duration

The ECM contains memories for the basic discharge durations at various engine speeds and manifold pressures. The

basic discharge duration, after being read out from the memory, is further modified by signals sent from various sensors

to obtain the final discharge duration.

Idle Air Control

Idle Air Control (IAC) Valve

When the engine is cold, the A/C compressor is on, the transmission is in gear (A/T only) or the alternator (ALT) is charg-

ing, the ECM controls current to the IAC valve to maintain correct idle speed.

Ignition Timing Control

The ECM contains memories for basic ignition timing at various engine speeds and manifold pressures. Ignition timing

is also adjusted for engine coolant temperature.

A knock control system is also used. When detonation is detected by the knock sensor (KS), the ignition timing is

retarded.

Other Control Functions

1. Starting Control

When the engine is started, the ECM provides a rich mixture by increasing fuel injector duration.

2. Fuel Pump Control

When the ignition switch is initially turned on, the ECM supplies ground to the PGM-FI main relay that supplies

current to the fuel pump for two seconds to pressurize the fuel system.

When the engine is running, the ECM supplies ground to the PGM-FI main relay that supplies current to the fuel pump.

When the engine is not running and the ignition is on, the ECM cuts ground to the PGM-FI main relay which cuts

current to the fuel pump.

Excellent engine performance is achieved through the use of VTEC (Variable Valve Timing and Valve Lift Electron-

ic Control System), intake air bypass control and discharge volume control of the fuel pump.ProCarManuals.com