Page 326 of 1395

PGM-FI System
Fuel Supply System
[POliil The"""ntool indicates Diagnostic Troubte Code (DTC) p0'171:Thefuet system istoo lean.
[Fo17ZJ rh""""ntool indicates Diagnostic Troubte code {DTc) p0172:Thefuel svstem istoorich.
Description
By monitoring the Long Term Fuel rrim, long term malfunctions in the fuel system will be detected.lf a malfunction has been detected during two consecutive trips, the MIL will come on and DTc p0171 and/or pol72 will bestored.
NOTE: lf someof the DTCS listed below are stored atthesametimeas DTC P017'l and/or p0172, troubleshoot those DTcsfirst, then troubleshoot DTC P0171 and/or PO1i2.
P0107, P0108, P1128, P'1129: MAP Sensor
P0135: Primary HO2S (Sensor 1)Heater
P0137, P0138: Secondary HO2S {Sensor 2)P0141: Secondary H02S (Sensor 2) Heater
P0441*r: EVAP System lnsufficient Purge FtowP1456*,, P'l457 *?i EVAP System Insufficient purge Ftow
Possible Cause
DTC P0171
too lean
*1: '97 model*2: '98 - 00 models
Fuel Pump insufficient flow/pressure
Fuel Feed Line clogged. leaking
Fuel Pressure Regulator stuck openFuel Filter clogged
Fuel Injector clogged, air leakage
Gasoline doesn't meet Owner's Manual spec.Primary HO2S (Sensor 1) deteriorated
Valve Clearance
Exhaust leak
Fuel Pressure Regulator clogged, stuck closedFuel Return Pipe clogged
Fuel Injector leaking
Gasoline doesn't meet Owner's Manual spec.Primary H02S (Sensor 1) deteriorated
EVAP Purge Control Solenoid Valve leaking, stuck openedValve Clearance
DTC P0172
flch
11-124
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Page 327 of 1395
Troubleshooting Flowchart
- The MIL has been rePorted on- DTC P0171 andlot P0172 are
stored,
Check the lu6l pressuro regulator
and tusl relum PiPe.ls the lLrel pressure too high
Check lhe Primaty HO2S:1. Start the engine. Hold the
engine at 3,000 rpm with no
load (in Park ot neutral) until
the radiator fan comes on
2. Check the Primary HO2S(Sensor 1) outPut with the
scan tool.
Check lh€ fuel pumP. fuel faedpipe. fuel fiher, and luel Prossurc.eguhior.
Does it stay at lessthan 0.3 V
or more than 0.6 V?
Check for a sticking or leaking
EVAP purge control solenoid
With a vacuum pump, aPPIY vacu
um to the EVAP Purge control
solenoid valve from the intake
manifold side.
Does it hold vacuum?
Check th6 valve clearanc€s and
adjust il necessary. It the valv€
clearances are OK, replace the
fuel iniectors.
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Page 328 of 1395

PGM-FI System
Random Misfire
lF()gool", tftod-' and some or lpiogol throughTo3oti
The scan tool indicates Diagnostic Trouble Code (DTC)
P0300*,, P1300*1 and some of po30t - pO3O4; Randommisfire.
Descriotion
Misfire detection is accomplished by monitoring the crankshaft speed with the crankshaft speed fluctuation (cKF) sensorwhich is attached to the crankshaft.lfmisfiring strong enough to damage the catalyst is detected, the MIL will blink during the time of its occurrence, and DTcP0300*' , P1300*1 and some of DTCs P03ol through P0304 will be stored. Then, after misfire has ceased, the MtL will comeon,
lf misfiring that increases emissions is detected during two consecutive driving cycles, the MIL will come on, and DTcand some of DTCS p0301 through p0304 wi
be stored.NOTE: lf some of the DTCS listed below are stored at the same time as a misfire DTc, troubleshoot those DTcs first. thentroubleshoot the misfire DTC.
P0106, P]128, P1'129; MAp sensorP0171. P0172; Fuet metering
P0505: ldle Control Svstem
P1336, P1337; CKF sensor
P1361, P1362: TDC sensor
Pl381. Pl382: CYP sensor
P1508: IAC valve *1:,97 model*2: '98 - 00 models
Possiblo Caus€
. Fuel pump insufficient fuel pressure, amountofflow. Fuel line clogging. blockage, leakage. Fuel filter clogginga Fuel pressure regulator stuck open. Distributormalfunction
. lgnition coil wire open, leakage. lgnition control module malfunction. Valves carbon deposita Compression lowa Fuel does not meet Owner's Manual spec., lack offuel
Troubleshooting
By test-driving, determine the conditions during which misfire occurs. Depending on these conditions, test in the orderdescribed in the table below.
Possible cause
[ ;;;;- -....
Crankshaft
speed fluctuation
sensor
Fuel
pressureDistributor and
lgnition wirestcMValve
Clearance
Conditionsection 611-178section 23section 23section 6
Only low rpm and load,6)o
Only acceleratingooo
Only high rpm and loado@,a'@
Not specificationG\o@o@
NOTE: lf misfire doesn't recur, some possible causes are fuel that doesn't meet owner's manual spec, lack of fuel, carbondeposits on spark plu9, etc.
11-126
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Page 375 of 1395
'97 model:
Check all hose clamps, and retighten if necessary.
FUELFILTER
/\
{"2
,"1<,, I___--tJ
B
FUEL TUBE/OUICK-CONNECTFITTINGS
EVAPORATIVEEMISSION {EVAP}CONTBOLCANISTER
'^s
,4\-') |Ift q'l I
/'------/
/B,To FUELPRESSUREREGULATOR
10-14mm(0.39 - 0.55 inl
(cont'd)
11-173
Clamp in the middle
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Page 376 of 1395
Fuel Supply System
Fuel Lines (confd)
'98 - (X) models:
Check all hose clamps, and retighten if necessary.
SASEGASKETReplace.
FUELFILTER
To FUELPRESSUREREGULATOR
10-14mm(0.39 - 0.ss in)
Clamp in the middle
11-174
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Page 377 of 1395

Fuel Tube/Ouick-Gonnect Fittings
Procautions
@ Do not smoke whils working on the fuel
syst6m, Koop open flames away from your work ar9a.
The fuel tube/quick-connect fittings assembly connects
the in-tank fuel pump with the fuel feed pipe. For remov-
ing or installing the fuel pump and fuel tank, it is neces-
sary to disconnect or connect the quick-connect fittings.
Pay attention to following;
. The fuel tube/quick-connect fittings assembly is not
heat-resistant; be careful not to damage it during weld-
ing or other heat-generating procedures.
. The fuel tube/quick-connect fittings assembly is not
acid-proof; do not touch it with a shop towel which
was used for wiping battery electrolyte. R€place the
fuel tube/quick-connect fittings assembly if it came
into contact with electrolyte or somethino similar.
. When connecting or disconnecting the fuel tube/quick-
connect fittings assembly, be careful not to bend or
twist it excessively, Replace it if damaged,
A disconnected quick-connect fittings can be reconnected,
but the retainer on the mating pipe cannot be reused once
it has been removed from the pipe. Replace tha retainer
. replacing the fuel pump.
. replacing the fuelfeed pipe,
. it has been removed from the Dioe,
. it is damaged.
RCTAINERFUEL TUBE
CONNECTOR
CONNECTOR
RETAINER
11-175
Disconnection
!@ Do not smoke while working on the fuel
syst6m. Keep open flames away from your work area.
1. Disconnect the battery negative cable.
2. Remove the fuel fill cap to relieve fuel pressure in
the tank.
3. Relieve fuel pressure (see page 11-178).
4. Check the fuel quick-connect fittings for dirt, and
clean if necessary.
5. Hold the connector with one hand and press down
the retainer tabs with the other hand. then pull the
connector off.
NOTE:
. Be careful not to damage the pipe or other parts.
Do not use tools,
. lf the connector does not move, keep the retainer
tabs pressed down, and alternately pull and push
the connector until it comes off easily.
. Do not remove the retainer from the pipe; once
removed, the retainer must be replaced with a
new one.
LOCKII{G PAWL
RETANEN TAB
@NNCCTOR
Press down.
6. Check the contact area of the pipe for dirt and dam-
age.
. lf the surface is dirW, clean it
. lf the surface is rusty or damaged, replace the fuel
pump or fuel feed pipe,
CONTACT ANEA
{cont'd}
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Page 379 of 1395
3. Before connecting a new fuel tube/quick-connect fit-
ting assembly, remove the old retainer from the
mating pipe.
with thetabs pulled
apart, removeand discardthe retarner
Ncw FUEL TUBE/OUICK.CONNECTFI?TING ASSEMBLY
4.Align the quick-connect fittings with the pipe. and
align the retainer locking pawls with the connector
grooves. Then press the quick-connect fittings onto
the pipe until both retainer pawls lock with a click-
Ing sound.
NOTE: lf it is hard to connect, put a small amount of
new engine oil on the pipe end.
5. Make sure the connection is secure and that the pawls
are firmly locked into place; check visually and bypulling the connector.
Reconnect the battery negative cable, and turn the
ignition switch ON (ll). The fuel pump will run for
about two seconds, and fuel pressure will rise. Repeat
two or three times, and check that there is no leakage
in the fuel supply system.
6.
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Page 380 of 1395

Fuel Supply System
System Description
The fuel supply system consists of a fuel tank, in-tank
high-pressure fuel pump. PGM-Fl main relay, fuel filter,
fuel pressure regulator, fuel injectors, and fuel delivery
and return lines. This system delivers pressure-regulat-
ed fuel to the fuel injectors and cuts the fuel delivery
when the engine is not running.
Fuel Pressure
Relieving
Before disconnecting fuel pipes or hoses, release pres-
sure from the system by loosening the 12 mm banjo
bolt on the too of the fuel filter.
Do not smoke while working on the fuel system.
Ke€p open flames or sparks away from your work
area,
Be sure to relieve fuel pressure while the ignition
switch is off.
Write down the frequencies for the radio's preset
buttons.
Disconnect the battery negative cable from the bat-
tery negative terminal.
Remove the fuel fill cap.
Use a box end wrench on the 12 mm banjo bolt at
the fuel filter while holding the fuel filter with anoth-
er wrench.
Place a rag or shop towel over the '12 mm banjo bolt.
Slowly loosen the 12 mm banjo bolt one complete
rurn 12 mm BANJoBOLT
1.
SHOP TOWEL
NOTE: Replace the washers whenever the 12 mm
banio bolt is loosened or removed.
11-178
Inspection
1, Relieve fuel pressure.
2. Remove the 12 mm banjo bolt on the fuel filter while
holding the fuel filter with another wrench. Attach
the 12 mm fuel pressure adapter bolt and the special
tool.
FUEL PRESSUREREGULATON
FUELPRESSUREGAUGE07406 - 0040001
The illustration shows'97 - 98 models,'99 - 00 models are similar.
Start the engine. Measure the fuel pressure with the
engine idling and the vacuum hose of the fuel pres-
sure regulator disconnected from the fuel pressure
regulator and pinched. lf the engine will not start,
turn the ignition switch on (ll), wait for two seconds,
turn it off, then back on again and read the fuel
pressure.
Pressure should be:'97 - 98 mod€ls:
260 -31O kPa 12.7 - 3.2 kgf/cm,, 38 - 46 psil'99 - 0O models:
270 - 32O kPa Q.A - 3.2 kgf/cm' , ifo - /U psil
Reconnect vacuum hose to the fuel pressure regulator.
Prgs3ure should be:'97 - 98 models:
210 - 25O kPa 12.1- 2.6 kgf/cm' , 30 - 37 psi)'99 - 00 models:
22O -26iJ kPa 12.2 - 2.7 kgt/cm' , 31 - 38 psi)
lf the fuel pressure is not as specified, first check the
fuel pump (see page 11- 183). lf the fuel pump is OK,
check the following:
. lf the fuel pressure is higher than specified,
inspect for:- Pinched or clogged fuel return hose or line.- Faulty fuel pressure regulator (see page 11-
181).
. lf the fuel pressure is lower than specified. inspect
for:- Clogged fuel filter.- Faulty fuel pressure regulator (see page 11-
1811.- Fuel line leakage.
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