1991 ACURA NSX fuel pump

5. Install the side engine mount, then tighten the bolts
in the numbered sequence as shown ( - ),

12 x
1.26
mm

73 N·m
(7.3 kg-m,
53 Ib-ft)

Replace.
12 x
1.25
mm

95 N·m
(9.5 kg-m,
69 Ib-ft)

SIDE ENGINE

MOUNT

6. Tighten the transmission mount mounting bolt.

MOUNTING BOLT
12 x
1.25
mm

95 N·m (9.5 kg-m, 69 Ib-ft)
7. Tighten the rear mount mounting bolt.
MOUNTING BOLT

12 x
1.25
mm

77 N·m (7.7 kg-m, 56 Ib-ft)
Replace.

Check that the spring clip on the end of each
driveshaft clicks into place.
CAUTION: Use new spring clips.
Bleed air from the cooling system (see page 10-5).
Bleed air from the brake lines {see section 19).
Check the clutch pedal free play (see section 12).

Adjust the clutch guide assemblies when disas-

sembling clutch (see section 12).

Check that the transmission shifts into gear

smoothly.

Adjust the alternator belt (see section 23).
Adjust the A/C compressor belt (see section 22).
Clean battery posts and cable terminals with
sandpaper, assemble, then apply grease to pre-
vent corrosion.
Inspect for fuel leakage (see section 11). After assembling the fuel line parts, turn on
the ignition switch (do not operate the starter) so that the fuel pump operates for approxi-
mately two seconds and the fuel line pressu-
rizes. Repeat this operation two or three times
and check for fuel leakage at any point in the

fuel line.

Check and adjust wheel alignment (see section 18).

Refill the engine with engine oil (see page 8-4 ('91-'92
Models), ('93-Model),or ('94-'96 Models).

Refill the transmission with oil/fluid (see section

13 or
14).ProCarManuals.com

PGM-FI System

System Description

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.

Throttle Valve Control

The ECM controls the throttle valve control motor based on accelerator pedal position, TCS control unit and various sig-

nals. The ECM also controls the idle control function, cruise control function, and other functions with the throttle valve

control.

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 Electronic

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

13. Install the fuel injectors and fuel rail assembly in the manifold.

CAUTION: To prevent damage to the O-rings, install the fuel injectors in the fuel rail first, then install them in the

intake manifold.

FUEL

RAILS

FUEL RAIL

INSULATOR

FUEL RAIL
14. Align the center line on the connector with the mark on the fuel rail.

15. Install and tighten the retainer nuts.

16. Connect the fuel hose to the fuel rail.

17. Connect the vacuum hose and fuel return hose to the fuel pressure regulator.

18. Install the connectors on the fuel injectors and the IAT sensor.

19. Install the intake manifold covers.

20. Turn the ignition switch ON (II), but do not operate the starter. After the fuel pump runs for approximately two seconds,

the fuel pressure in the fuel line rises. Repeat this two or three times, then check whether there is any fuel leakage.
MARKINGSProCarManuals.com

Fuel Pum p Rela y
Troubleshootin g Flowchar t
Inspection o f fue l pum p relay .
Tur n th e ignitio n switc h t o STAR T
(III) position .
Does th e engin e start ?
Chec k fo r a n ope n in th e circuit :
1 . Sto p th e engine .
2. Tur n th e ignitio n switc h O N (II) .3. Measur e voltag e betwee n
EC M connecto r termina l F 4
an d bod y ground .
I s ther e batter y voltage ?
Proble m verification :
1 . Star t th e engine . Hol d th e
engin e a t 3,00 0 rp m wit h n o
loa d (A/ T in position ,M/T in neutral ) unti l th e radia -
to r fa n come s on , the n le t i t
idl e fo r a t leas t on e minute .
2. Tur n th e ignitio n switc h OFF .3. Disconnec t # 4 hos e fro m th e
instal l pipe , connec t vacuu m
pum p t o th e hose .
4 . Appl y vacuu m 2 7 t o 4 0 kp a
(200 t o 300 mmHg , 8 to 1 2in.Hg) .
5 . Star t th e engine .
6 . Hol d engin e spee d a t 6,50 0
rpm (A/ T in position ,M/T in neutral) .
7 . Measur e voltag e betwee n
EC M connecto r termina l F 4
an d bod y ground .
I s ther e les s tha n 1. 0 V ? Inspec
t th e fue l pum p resisto r
(se e pag e 11-141 ).
ECM CONNECTO R F (26P )
WIR E SID E O F FEMAL E TERMINAL S
(T o pag e 11-140 )
4 HOS E
CONTRO LBOX
VACUU M PUMP /GAUGEA973X-04 1-XXXX X
Substitut e a known-goo d EC M
an d recheck . I f prescribe d volt -
ag e i s no w available , replac e th e
origina l ECM .
Fue l pum p rela y circui t i s OK .
ProCarManuals.com

Fuel Pum p Resisto r
Troubleshootin g Flowchar t
— Engin e wil l no t start .
— Inspectio n o f fue l pum p resis -
tor.
Chec k th e operatio n o f th e PGM -
F I mai n relay :
1 . Disconnec t th e fue l pum p
resisto r 2 P connector .
2 . Measur e voltag e betwee n fue l
pum p resisto r connecto r ter -
mina l No . 2 an d bod y groun d
when th e ignitio n switc h i sfirs t turne d O N (II) .
I s ther e batter y voltage ?
(fo r 2 seconds )
Doe s th e engin e start ?
Chec k fo r a n ope n in th e wire :
1 . Tur n th e ignitio n switc h OFF .
2 . Disconnec t th e C48 6 (6P ) con -
necto r (locate d behin d th e
sea t bac k panels) .
3 . Measur e voltag e betwee n th e
C48 6 (6P ) connecto r termina l
No . 3 an d bod y groun d whe n
the ignitio n switc h i s firs tturne d ON .
I s ther e batter y voltage ?
(fo r 2 seconds ) FUE
L PUM P RESISTO R 2P CONNECTO R
WIR E SID E O F FEMAL E TERMINAL S
Inspec t th e PGM-F I mai n rela y
(se e pag e 11-143 ).
Replac e th e fue l pum p resistor .
C489 CONNECTO R (6P )
Inspec t th e fue l pum p (se e pag e
11-142 ).
TERMINA L SID E O F MAL E TERMINAL S
JUMPE
R WIR E
Chec k fo r a n ope n i n th e fue l
pum p resistor :
1 . Tur n th e ignitio n switc h OFF .
2 . Connec t fue l pum p resisto r
connecto r terminal s No . 1 an d
No. 2 wit h a jumpe r wire .3. Tur n th e ignitio n switc h t o
STAR T position .
Repai r ope n i n BLK/RE D wir e
betwee n th e fue l pum p resisto r
an d th e fue l pump .
ProCarManuals.com

Fuel Suppl y Syste m
Fuel Pum p
Testin g
Do no t smok e durin g th e test . Kee p ope n
flam e awa y fro m you r wor k area .
I f yo u suspec t a proble m wit h th e fue l pump , chec k tha t
th e fue l pum p actuall y runs . Whe n it i s ON , yo u wil l hea r
som e nois e i f yo u hol d you r ea r t o th e fue l fil l por t wit h
th e fue l fil l ca p removed . Th e fue l pum p shoul d ru n fo r
tw o second s whe n th e ignitio n switc h i s firs t turne d on .
I f th e fue l pum p doe s no t mak e noise , chec k a s follows :
1 . Remov e th e bulkhea d panels .
2 . Disconnec t th e C48 6 (6P ) connecto r (locate d behin d
th e bulkhea d panels) .
CAUTION : B e sur e t o tur n th e ignitio n switc h OF F
befor e disconnectin g th e wires .
3 . Disconnec t th e PGM-F I mai n rela y connecto r an d
connec t th e No . 2 termina l an d No . 5 terminal * wit h
a jumpe r wire . * : 8 P connecto r
PGM-FI MAI N RELA Y CONNECTOR S
WIR E SID E O F FEMAL E TERMINAL S
4. Chec k tha t batter y voltag e i s availabl e a t th e fue l
pum p connecto r whe n th e ignitio n switc h i s turne d
O N (positiv e prob e t o th e No . 3 terminal , negativ e
prob e t o No . 6 termina l wire) .
C486 CONNECTO R (6P )
(BLK )
(BLK/YEL )
TERMINAL
SID E O F
MAL E TERMINAL S
If batter y voltag e i s available , replac e th e fue l
pump .
I f ther e i s n o voltage , chec k th e fue l pum p
groun d an d wir e harnes s (se e pag e 11-144 ).
Replacemen t
Do no t smok e whil e workin g o n fue l sys -
tem. Kee p ope n flame s awa y fro m you r wor k area .
1 . Remov e th e fue l tan k (se e pag e 11-147 ).
2 . Disconnec t th e connecto r fro m th e fue l pump .
3 . Remov e th e fue l pum p mountin g nuts .
4 . Remov e th e fue l pum p fro m th e fue l tank .
27 N- m (2. 8 kgf-m , 2 1 Ibf-ft )
5. 9 N- m (0. 6 kgf-m ,
4. 3 Ibf-ft )
FUE L PUM P FUE
L PUM P
BRACKE T
ProCarManuals.com

Fuel Suppl y Syste m
PGM-F I Mai n Rela y
Troubleshootin g
Is ther e continuity ?
Chec k fo r a n ope n o r shor t i n th e
wire :Measur e voltag e betwee n th e
PGM-F I mai n rela y 4 P connecto r
terminal No . 3 an d bod y ground .
Is ther e batter y voltage ?
Chec k fo r a n ope n o r shor t i n th e
wire :
1. Tur n th e ignitio n switc h O N (II) .2. Measur e voltag e betwee n th e
PGM-F I mai n rela y 8 P connec -
tor termina l No . 5 an d bod yground .
PGM-FI MAI N RELA Y 8 P CONNECTO R
WIR E SID E O F FEMAL E TERMINAL S
Repai r ope n i n th e wir e betwee n
th e PGM-F I mai n rela y an d G10 1
(locate d a t righ t middl e o fengine) .
PGM-FI MAI N RELA Y 4 P CONNECTO R
Replac e th e ACG(S ) (2 0 A )
fus e i n th e engin e compart -
men t fuse/rela y box .
Repai r ope n o r shor t i n th e
wir e betwee n th e PGM-F Imain rela y an d th e ACG(S )
(2 0 A ) fuse . WIR
E SID E O F FEMAL E TERMINAL S
I s ther e batter y voltage ?
(T o pag e 11-145 ) Replac
e th e No . 2 FUE L
PUMP , SR S 2 (1 5 A ) fus e i n
th e under-das h fus e box .
Repai r ope n o r shor t i n th e
wir e betwee n th e PGM-F Imain rela y an d th e No . 2 FUE L
PUMP , SR S 2 (1 5 A ) fuse .
Engin
e wil l no t start .
Inspectio n o f PGM-F I mai n
rela y an d rela y harness .
Chec k fo r a n ope n in th e wire :
1. Tur n th e ignitio n switc h OFF .2. Disconnec t th e PGM-F I mai n
rela y 4 P connecto r an d 8 P
connector .
3 . Chec k fo r continuit y betwee n
th e PGM-F I mai n rela y 8 P
connecto r termina l No . 7 an d
body ground .
ProCarManuals.com

Engine Removal/Installation

(cont'd)

10. Disconnect the resistor connector and fan motor connector, then remove the engine room fan
assembly.
ENGINE ROOM

FAN
ENGINE ROOM
FAN CONNECTOR
GROMMET
11. Remove the rear trim panels behind the
passenger's seat, then disconnect four connectors
from Engine Control Module (ECM) and five con- nectors from floor wire harness.
ENGINE WIRE
HARNESS CONNECTORS
ECM

PASSENGER'S

SEAT

FLOOR WIRE HARNESS
ENGINE WIRE

HARNESS

FUEL PUMP RESISTOR
CONNECTORGROUND

CABLE

6x1.0
mm

10 N.m (1.0 kg-m, 7 Ib-ft)
CORROSION RESISTANT BOLT
6 x 1.0 mm

10 N.m d.Okg.m, 7 Ib-ft)ProCarManuals.com