2003 HONDA CIVIC fuel pressure

Fuel Tank Replacement
Relievethefuel pressure (see page 11-144).
Drain the fuel tank: Remove the fuel pump (see page 1 1-153). Using a hand pump, hose, and container suitable for
gasoline. draw the fuel from the fuel tank.
Jack up the vehicle, and suppon it with safety stands.
Remove the fuel pipe cover (A). Disconnect the fuel vapor hose and quick-connect fittings.
Disconnect the hoses. Slide back the clamps (B), then twist the hoses as you pull to avoid damaging them.
A 38 N.m(3.9 ksf.m,28lbfft)
5. Place a jack or other support under the tank.
6. Removethe strap bolts, and letthestrap (C) hangfree.
7. Remove the fuel tank (D). lf itstickstothe undercoaton its mount, carefully pry itoffthe mount
8. Install the parts in the reverse order of removal.
1.
2.
3.
(}
\
11-155

10. Checkthatthe pointerof thefuel gauge indicates"F".
. lf the pointer does not indicate "F", replace the
ga uge.. lf the pointer indicates "F", inspect the fuel
gauge sending unit.
NOTE: The pointer of the fuel gauge retu rns to the
bottom of the gauge dial when the ignition switch
is OFF, regardless of the fuel level. -
11. Relieve the fuel pressure (see page 11-144\.
12. Remove the fuelfill cap.
13. Disconnect the quick-connect fittings from the fuel
pump.
14. Using the special tool, loosen the fuel tank unit
locknut (A).
A93Nm{9.5 ksf.m,69 lbf.ft}
15. Measure resistance between the No. 1 and No.2
terminals with the float at E (EN4PTY), 'l12 \HALF
FULL), and F {FULL) positions.
lf you do not get the following readings, replace the
fuel gauge sending unit {see page 1'1-163).
Float
Position
F'U2LOWE
Resistance
{0)
11
to 13
68,5
to 74.5
114.4
to 126.6
130
to 132
NOTE: Remove the No. 9 BACK UP (7.5A) fuse from
the under-hood fuse/relay box for at least 10
seconds after completing troubleshooting,
otherwise it may take up to 20 minutes for the fuel
gauge to indicate the correct fuel level.
11-157

EVAP System
Component Location Index
EVAPORATIVE EMISSION {EVAP)CANISTER VENT SHUT VALVETroubleshooting,step 23 on page 1'l 178,step 1g on page l1- 182
EVAPORATIVE EMISSION IEVAPICANISTER PURGE VALVETroubleshooting,step 3 on page 'l1-175,
step 1on page 11-180
FUEL TANK VAPOR CONTROL VALVETest, page 11'187Replacement, page 11 189
FUEL TANK PRESSURE SENSORTroubleshooting, page 1 1-171
EVAPORATIVE EMISSION {EVAPICANISTERTroubleshooting, step 28 on page 11'183Replacement, page 1 1-189
EVAPORATIVE EMISSION {EVAP}BYPASS SOLENOID VALVETroubleshooting,step 12 on page '11'176,
step '10 on page 11 181
EVAPOBATIVE EMISSON {EVAP)TWO WAY VALVETest, page 'l1-'186
11-170

DTC Troubleshooting
DTC P0451: FTP Sensor Range/Performa nce
Problem
Special Tools Required
Vacuum Pump/Gauge, 0-30 in. Hg A973X-041-XXXXX
1. Remove the fuel fill cap.
2. Turn the ignition switch ON (ll)
3. l\4onitor fuel tank pressure (FTP) sensorvoltage
with the Honda PGM Tester, or medsure voltage
between ECM connectorterminals E4 and E14.
ECM CONNECTOR E 131P)
Wire side of female terminals
ls there about 2.5V?
YES-Go to step 4.
NO Replace the FTP sensor.I
Turn the ignition switch OFF.
Disconnect the hose between the EVAP two way
valve and the FTP sensor at the EVAP two way
valve end.
4.
5.
7.
8.
6. Connect a vacuum pump to the open end of the
hose.
Turn the ignition switch ON {ll).
l\4onitor FTP sensor voltage with the Honds PGM
Tester, or measure voltage between ECM
connector terminals E4 and E14, and carefully
squeeze the vacuum pump a little.
ECM CONNECTOR E 13lPI
Wire side of lemale terminals
The voltage should smoothly drop from about 2.5 V
to about 1.5 V. Stop applying vacuum when the
voltage drops to about 1.5 V or damage to the FTP
sensor may occur.
Does the voltage drop to about 1.5 V and hold?
YES Check for misrouted, leaking, or broken FTP
sensor vacuum lines. lf the vacuum lines are OK,
update the ECM if it does not have the latest
software. or substitute a known-good ECM, then
recheck (see page 1 1-6). lf the symptom/indication
goes away with a known-good ECM, replace the
original ECM.I
NO Replace the FTP sensor. !
9.
11-171

EVAP System
DTC Troubleshooting (cont'd)
DTC P0452: FTP Sensor Circuit Low Voltage
1. Check the vacuum lines at the FTP sensor for
misrouting, leakage. breakage, or clogging.
Are the vacuum lines OK?
YES Go to step 2.
NO Repair or replace vacuum lines as
necessary. I
2. Reset the ECM (see page 11-4).
3. Remove the fuelfill cap.
4. Turn the ignition switch ON (ll)
5. Monitor FTP sensor voltage with the Honda PGM
Tester, or measure voltage between body ground
and ECM connector terminal E14.
ECM CONNECTOR E 131PI
1 2t3t45o/89
././114tc61./182C21
22123241 t26271/ 2931
TP (LT GRN)
Wire side of female terminals
ls thete about 2.5 V?
YES- Intermittent failure, system is OK at this time.
Check for poor connections or loose terminals at
the FTP sensor and at the ECrM.l
NO Go to step 6.
11-172
6. Turn the ignition switch OFF.
7. Reinstallthe fuel fill cap.
8. Disconnect the FTP sensor 3P connector.
9. Turn the ignition switch ON (ll)
10. Measure voltage between FTP sensor 3P connector
terminals No. 1 and No.2.
FUEL TANK PRESSURE SENSOR 3P CONNECTOR
VCgl {YEL/BLU}
Wire side of female terminals
ls there about 5 V?
YES Go to step 1 '1.
NO-Repair open in the wire between the FTP
sensor and the ECM {E5).1

DTC Pl456: EVAP Control(Fuel Tank Svstem)
System Leakage
The fuel system is designed to allow specified
maximum vacuum and pressure conditions. Do not
deviate from the vacuum and pressure tests as
indicated in these procedures. Excessive pressure/
vacuum would damage the EVAP components or cause
eventual fuel tank failure.
Special Tools Required
Vacuum Pump/Gauge, 0-30 in. Hg A973X-041-XXXXX
This is a two-trip code. Once cleared, it cannot be
reproduced in one trip. Also, cenain specific driving
and ambient conditions must occur before the ECM will
complete the system checks. Additional test drives may
still not meet the specific conditions needed to
reproduce the code.
Follow these troubleshooting procedures carefully to
ensure the integrity of the system and to confirm the
cause of the problem or code.
NOTE: Fresh fuel has a higher volatility that createsgreater pressure/vacuum. The optimum condltlon for
testing is fresh fuel, and must be less than a full tank. lf
possible, to assist in leak detection, add 1 gallon of
fresh fuel to the tank (as long as it will not fill the tank).just before starting these procedures.
Fuel Fill Cap Check
1. Check the fuel fill cap (the cap must say "lf not
tightened 3 clicks check engine light may come
on" ).
ls the proper luel till cap installed and properly
tightened?
YES Go to step 2.
NO- Replace or tighten the cap.I
2. Check the fuel fill cap seal.
ls the tuel fill cap seal missing or damaged?
YES- Replace the fuel fill cap.I
NO The fuelfill cap is OK. Go to step 3.
EVAP Canister Purge Valve Test
3. Disconnect the vacuum hose from the EVAP
canister purge valve (A), and connect a vacuum
oumo to the hose.
A973X-041-XXXXX
Turn the ignition switch ON (ll).
Apply vacuum to the hose.
Does the valve hold vacuum?
YES-The EVAP canister purge valve is OK. Go to
step 11.
NO-Go to step 6.
Turn the ignition switch OFF.
Disconnect the EVAP canister purge valve 2P
connecror.
5.
7.
{cont'd)
11-175

28.
29.
ls thete continuity?
YES-Go to step 28.
NO-Replace the EVAP canister vent shut valve (A)
and o-ring (B).1
Disconnect ECM connector E (31P).
Check for continuity between EVAP canister vent
solenoid valve 2P connector terminal No. 2 and
body ground.
EVAP CANISTER VENT SHUTVALVE 2P CONNECTOR
Wire side o{ female terminals
ls there continuity?
YES-Repair short in the wire between the EVAP
canister vent shut valve and the ECM (E21).1
NO Update the ECM if it does not have the latest
soflware, or substitute a known-good ECM, then
recheck (see page 11-6). lf the symptom/indication
goes away with a known-good ECM, replace the
original ECM.I
30.
Vacuum Hoses and Connections Test
Do the fuel tank vapor control valve test (see page
1 1-187).
ls the fuel tank vapot control valve OK?
YES-Go to step 31.
NO Replace the fueltank vapor control valve.l
Tighten the fuel cap 3 "clicks", then monitorthe
FTP sensor readings with the Honda PGM Tester.
Start the engine. and let it idle for 5 minutes.
Check the FTP sensor readings.
ls the reading above 0.5 kpa (4 mm Hg, 0.16 in.
Hg) pressure, or about 3 V?
YES Update the ECM if it does not have the latest
software, or substitute a known-good ECM, then
recheck {see page 1 1-6). lf the symptom/indication
goes away with a known-good ECfvl, replace the
original ECM.t
NO Check the following parts for leaks:l
. Fueltank (A)
. Fuel fill cap (B)
. Fuel fill pipe (C)
. Fueltank vapor control valve(D). Fueltank vapor recirculation valve (E)
. Fueltank vapor recirculation tube (F)
. Fueltank vapor signaltube (G)
. Fueltank vapor control venttube(H). FTP sensor (J)
- Repair or replace any leaking parts.
5t.
11-179

EVAP System
DTC Troubleshooting (cont'd)
DTC Pl457: EVAP Control System(EVAP Canister System)
Leakage
The fuel system is designed to allow specified
maximum vacuum and pressure conditions. Do not
deviate from the vacuum and pressure tests as
indicated in these procedures. Excessive pressure/
vacuum would damage the EVAP components or
cause eventual fuel tank system failure.
SpecialTools Required
Vacuum pump/gauge, 0-30 in.Hg A973X-041-XXXXX
This is a two-trip code. Once cleared, it cannot be
reproduced in one trip. Also, certain specific driving
and ambient conditions must occur before the ECfM will
complete the system checks, Additional test drives may
still not meet the specific conditions needed to16^r^.1' '^6 rh6 ^^.16
Follow these troubleshooting procedures carefully to
ensure the integrity of the system and to confirm the
cause of the problem or code.
NOTE: Fresh fuel has a higher volatility lhat creates
greater pressure/vacuum. The optimum condition for
testing is fresh fuel, and there must be less than a full
tank. lf possible, to assist in leak detection, add I gallon
of fresh fuel to the tank (as long as it will not fill the
tank), just before starting these procedures.
EVAP Canister Purge Valve Test
1. Disconnect the vacuum hose from the EVAP
canister purge valve (A), and connect a vacuumpump to the hose.
11-180
4973X-041-XXXXX
ECM CONNECTOR A I24P'
Wire side of lemale terminals
4.
7.
2. Turn the EVAP canister purge valve on with the
Honda PGM Tester, or connect ECM connector
terminal 821 to body ground with a jumper wire.
Turn the ignition switch ON (ll).
Apply vacuum to the hose.
Does the valve hold vacuum?
YES-Go to step 5.
NO-The EVAP canister purge valve is OK. Go to
step 10.
Turn the ignition switch OFF.
Disconnect the EVAP canister purge valve 2P
conneclor,
Check for continuity between EVAP canister purge
valve 2P connector terminal No. 2 and body ground.
EVAPCANISTEN PURG€VALVE 2P CONNECTOR
-4-
lll2l-fircs
IYEL/8Lu)(f])
I
Wire side offemale lerminals
ls there continuity?
YES-Go to step 8.
NO Repair open in the wire between the EVAP
canister purge valve and the ECM/PCM (821).I
Turn the ignition switch ON (ll).
t
b.
8.