Honda CR-V 1997 Service Manual page 410

Emission Control System
Evaporative Emission (EVAP) Controls (cont'd)
'99 - 00 models:
I
P0451
I
The scan tool indicates Diagnostic Trouble Code (DTC) P0451: The Fuel Tank Pressure sensor circuit rangel
performance problem .
-
The MIL
hIS
been reported on.
-
Ole P0451 is stored.
Check for the fuel tank pressure
sensor:
1-
Do the ECM/PCM Reset Proce-
dure.
2.
Rem ove the fuel fill cap.
3. Turn the ignition switch ON
(lI).
4. Monitor the FTP Sensor volt-
age wi th t h e Honda PGM
Teste r, o r measure vo lta ge
between
ECM/PCM
connector
terminals A29 and C18.
Is there apprOX . 2.5 V?
YES
Check for the fuel tlnk pressure
sensor:
1.
Disconnect the hose between
the EVAP two way valve and
the fuel tank pressure sensor at
the EVAPtwo way va lve end.
2. Connect a vacuum pum p to
the open end of that hose.
3.
Turn the ignition switch ON (II).
,.
Monitor the FTP Sensor volt -
age with the Honda PGM
Tester. or measure voltage
between ECM/PCM co nnector
terminals A29 and C18. and
ca refully apply vacuum on the
hose one stroke at a time .
5. The voltag e should smoothly
drop from the st arting approx.
2.5 V down to approx. 1.5 V .
STOP applying vacu um when
the voltage drops to approx.
1.5 V o r damage to the fuel
tank p res sure se n sor may
occur.
Does the vo ltage drop to approx .
1.5 V and hold?
YES
Intermittent failure, system is OK
at
this time. Check for poor con-
nectioN or loose hose at fuel
t.nk pressure
,ensor and fuel
tenk.
11-208
AI3
V V
"-
NO
Check the vacuum tines for
restriction or blockage repair as
/ '
~ry .
tf OK, replace the fuel
tank pres.ure
sensor.
VACUUM
PUMP IGAUGE, 0
A973X - 041-
XXXXX
NO
Replace the fuel tank pressure
sensor.
ECM/PCM CONNECTORS
SG2 IGRN/BLK)
Wire side of female terminals
- 30 In.Hg
Ft'
FUEL TANK
PRESSURE
SENSOR
EVAPTWO
WAY VALVE