1991 MITSUBISHI MONTERO check engine

2.0L (VIN R) DOHC ......................... 137 (9.6)
2.0L (VIN U) DOHC Turbo ................... 114 (8.0)
2.0L (VIN V) SOHC ......................... 119 (8.4)
2.4L (VIN W) SOHC ......................... 119 (8.4)
3.0L (VIN S) SOHC ......................... 119 (8.4)
3.0L (VIN B) DOHC ......................... 139 (9.8)
3.0L (VIN C) DOHC Turbo ................... 115 (8.1)
(1) - Maximum variation between cylinders 14 psi
(1.0 kg/cm
)








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Exhaust System Backpressure
Exhaust system can be checked with a vacuum or pressure
gauge. Remove O2 sensor or air injection check valve (if equipped).
Connect a 1-10 psi pressure gauge and run engine at 2500 RPM. If
exhaust system backpressure is greater than 1 3/4-2 psi, exhaust
system or catalytic converter is plugged. If a vacuum gauge is used,
connect vacuum gauge hose to intake manifold vacuum port and start
engine. Observe vacuum gauge. Open throttle part way and hold steady.
If vacuum gauge reading slowly drops after stabilizing, exhaust system
should be checked for a restriction.
FUEL PRESSURE
Basic diagnosis of fuel system should begin with determining
fuel system pressure.
FUEL INJECTED ENGINES
WARNING: ALWAYS relieve fuel pressure before disconnecting any fuel
injection-related component. DO NOT allow fuel to contact
engine or electrical components.
Fuel Pressure
1) On all models except Colt and Mirage, disconnect fuel pump
harness connector at fuel tank. On Colt and Mirage, remove rear seat
cushion to disconnect fuel pump harness connector.
2) On all models, start engine. Let engine run until it
stops. Turn ignition off. Disconnect negative battery terminal.
Connect fuel pump harness connector.
WARNING: Before disconnecting high pressure fuel hose at fuel delivery
pipe, cover fuel hose connection with a rag. Some residual
fuel pressure may still be in system.
3) On Galant 2.0L (DOHC), remove brace for access to high
pressure fuel delivery pipe. On all engines, disconnect high pressure
fuel hose at fuel delivery pipe.
4) Connect fuel pressure gauge with adapter between fuel
delivery pipe and high pressure hose. See Fig. 1. Connect negative
battery terminal. Connect battery voltage to fuel pump test terminal.
See FUEL PUMP TEST TERMINAL LOCATION table. Ensure no fuel leaks are
present. Disconnect battery voltage to fuel pump test terminal.

Fig. 1: Fuel Pressure Testing Connection ID (Typical Fuel Inj. Eng.)
Courtesy of Mitsubishi Motor Sales of America.
5) Start engine and let idle. Measure fuel pressure with
vacuum hose connected to fuel pressure regulator. Record fuel pressure
reading. Disconnect and plug vacuum hose from fuel pressure regulator.
Record fuel pressure reading. See REGULATED FUEL PRESSURE table.
6) Check for fuel pressure in fuel return hose by gently
pinching hose while increasing engine speed. If fuel volume is low,
fuel pressure in return hose will not be felt. Increase engine speed
to 2500-3000 RPM, 2-3 times. Return engine to idle. Fuel pressure
should not drop when engine is returned to idle.
7) Turn engine off. Ensure fuel pressure reading does not
decrease within 2 minutes. If a decrease is noted, monitor speed of
decrease.
8) If fuel pressure is lower than specification, fuel
pressure drops at idle after increasing engine speed to 2500-3000 RPM,
or no fuel pressure in fuel return hose can be felt, check for clogged
fuel filter, faulty fuel pressure regulator, or fuel pump.
9) If fuel pressure is higher than specification, check for a
faulty fuel pressure regulator or plugged fuel return line. If fuel
pressure does not change when vacuum hose to regulator is connected or
disconnected, check for a leaking or clogged vacuum hose to fuel
pressure regulator or faulty fuel pressure regulator.
10) If fuel pressure decreases suddenly after engine is
stopped, check valve within fuel pump is not seated. Replace fuel

pump. If fuel pressure drops slowly, fuel injector is leaking or fuel
pressure regulator valve seat is leaking. Check for faulty fuel
injector or fuel pressure regulator. Repair as required.
11) When fuel pressure test is complete, repeat fuel pressure
release procedure in steps 1) and 2) before disconnecting fuel
pressure gauge. Install new "O" ring at end of high pressure hose.
Check for fuel leaks.
FUEL PUMP TEST TERMINAL LOCATION TABLE









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Application Wire Color Location
Colt, Colt 200 ......... BLK/WHT .............. Center Of Firewall
Colt Vista ............. BLK/WHT ........ Right Center Of Firewall
Eclipse ................ BLK/WHT .......... Rear Of Battery Compt.
Galant ................. YEL/GRN ........... Left Rear Eng. Compt.
Mirage 1.5L ............ BLK/WHT .............. Center Of Firewall
Mirage 1.6L ............ BLK/BLU .............. Center Of Firewall
Montero .................. WHT .......... Right Center Of Firewall
Pickup ................. BLK/BLU ....... Right Side Of Eng. Compt.
Precis ................... YEL ............. Left Rear Eng. Compt.
Summit ................. BLK/WHT .............. Center Of Firewall
Ram-50 ................. BLK/BLU ....... Right Side Of Eng. Compt.
Stealth, 3000GT ........ BLK/BLU .......... Rear Of Battery Compt.









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REGULATED FUEL PRESSURE TABLE








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At Idle At Idle
w/Vacuum w/o Vacuum
Application psi (kg/cm
) psi (kg/cm)
Non-Turbo .................. 38 (2.7) ....... 47-50 (3.3-3.5)
Turbo
Except Eclipse A/T ....... 27 (1.9) ....... 36-38 (2.5-2.7)
Eclipse A/T .............. 33 (2.3) ....... 36-38 (2.9-3.2)









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Control Relay
Multipurpose relay switches power to vehicle sensors and
actuators including airflow sensor, crank angle sensor, idle speed
control, injectors and fuel pump. When ignition switch is turned to ON
position, ECU energizes coils controlling injectors, airflow sensor
and idle speed control. When ignition switch is turned to START
position, ECU energizes coils (through inhibitor switch on A/T models)\
to supply power to fuel pump. Relay failure will cause a no-start
condition. For testing procedure, see SYSTEM & COMPONENT TESTING
article.
IGNITION CHECKS
SPARK
Check for spark at coil wire (if applicable) and at each
spark plug wire using a high output spark tester. Check spark plug
wire resistance on suspect wires. For wire resistance specification,
see C - SPECIFICATIONS article in the ENGINE PERFORMANCE Section.
CRANK ANGLE SENSOR
For crank angle sensor testing procedure on all models except
Ram-50, Stealth, Eclipse, Laser, Pickup and 3000GT, see TEST NS-5:

BRAK E S YSTE M

1991 M it s u bis h i M onte ro
1991 BRAKES
Disc & Drum
Chrysler Motors: Ram-50;
Mitsubishi: Montero, Pickup
DESCRIPTION
Brake system consists of a master cylinder, vacuum power
brake unit, proportioning valve and self-adjusting assembly. Pickup
and Ram-50 models have a Load-Sensing Proportioning Valve (LSPV). All
models are equipped with front disc brakes and rear drum brakes.
Parking brake assembly activates rear brakes.
BLEEDING BRAKE SYSTEM
BLEEDING PROCEDURES
Montero
Bleed brake system in following order: right rear, right
front and left front (one circuit handles both rear brakes).
Pickup & Ram-50
Bleed brake system in following order: right rear, left rear,
LSPV, right front and left front.
ADJUSTMENTS
BRAKE PEDAL HEIGHT & FREE PLAY
1) Separate connector from stoplight switch, and loosen lock
nut. Position switch so it does not contact brake pedal arm. Adjust
brake pedal height by rotating master cylinder push rod (yoke, if
equipped) until distance from top of brake pedal to floor board is
correct. See BRAKE PEDAL SPECIFICATIONS table.
2) DO NOT depress push rod. Tighten lock nut, and ensure
brake pedal height is within specification. Start engine to evacuate
brake booster chamber. Stop engine, and apply brake several times to
remove vacuum from brake booster.
3) Using hand pressure, depress brake pedal to measure free
play before resistance is felt. If distance is incorrect, bleed the
brake hydraulic system, and check for misadjusted brakes. Refer to the
BRAKE PEDAL SPECIFICATIONS table.
BRAKE PEDAL SPECIFICATIONS TABLE









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Free Play Pedal Height
Application In. (mm) In. (mm)
Montero ............ .12-.31 (3-8) ... 7.5-7.7 (191-196)
Pickup & Ram-50 .... .12-.31 (3-8) ........... 6.5 (166)









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LOAD-SENSING PROPORTIONING VALVE (LSPV) (Pickup & Ram-50)
Park vehicle on level surface. Remove all luggage and
passengers. Ensure lever is not against stopper bolt. Check spring

brake pedal to center shoes, and check pedal travel. Rotate brake drum
to verify free movement.
STOPLIGHT SWITCH
Loosen lock nut, and adjust switch-to-pedal arm clearance to
.02-.04" (.5-1.0 mm). Tighten lock nut. DO NOT depress master cylinder
push rod during stoplight switch adjustment.
TESTING
POWER BRAKE UNIT
Check Valve Inspection
Remove vacuum hose from power brake unit. Remove check valve
from hose (if possible). Using a vacuum pump, ensure airflow is in
direction of intake manifold only.
System Check
1) Run engine for 2 minutes, and shut it off. Depress brake
pedal several times with normal pressure. If pedal height gradually
becomes higher with successive applications, power brake unit is okay.
If pedal height remains steady, power brake unit is faulty.
2) With engine stopped, depress brake pedal repeatedly until
it's height no longer falls. Hold brake pedal down, and start engine.
If pedal moves downward slightly, power brake unit is okay. If pedal
height does not change, power brake unit is faulty.
3) With engine running, press and hold brake pedal and shut
off engine. Hold brake pedal for 30 seconds. Brake pedal height should
not change. If pedal height falls, power brake unit is faulty.
LOAD-SENSING PROPORTIONING VALVE (LSPV) (PICKUP & RAM-50)
1) Before diagnosing Load-Sensing Proportioning Valve (LSPV)\
,
ensure all other brake components are operating properly. When all
other brake system components are determined to be okay, perform LSPV
test beginning with next step.
2) Ensure unladen vehicle is on level ground. Ensure lever is
not contacting stopper bolt. See Fig. 1.
3) When lever is pushed toward valve, distance from LSPV
lever hole and support hole must be 6.97-7.09 in. (177-180 mm). If
measured distance is not within specification, loosen support bolt.
Adjust support until measured distance is within specification.
4) After measured distance is within specification, connect
pressure gauges to input and output ports of LSPV. See Fig. 4. Bleed
brake system. See BLEEDING BRAKE SYSTEM .
Fig. 4: Connecting Pressure Gauges to LSPV (Pickup & Ram-50)
Courtesy of Mitsubishi Motor Sales of America.

POWER BRAKE UNIT CHECK VALVE
NOTE: To test check valve before removal, stop engine, and apply
service brake to ensure air flows only toward intake
manifold.
Removal & Installation
Loosen hose clamps, and remove check valve. Before
installation, coat both ends of check valve with sealant, and install
valve with arrow (identification mark) pointing toward intake
manifold. Install check valve clamp, and secure hose clamps.
POWER BRAKE UNIT
Removal
Remove brake master cylinder. Disconnect vacuum hose from
power brake unit. Disconnect clevis pin attaching brake pedal to power
brake unit push rod. From inside vehicle, remove 4 nuts attaching
power brake unit to firewall. Remove power brake unit.
Installation
To install, reverse removal procedure. Install master
cylinder. Bleed brake system if necessary.
REAR AXLE BEARINGS & OIL SEAL
Removal (Montero)
1) With drum removed, disconnect brake line from wheel
cylinder. Disconnect bearing case from axle housing end. Remove brake
backing plate, bearing case and axle shaft as an assembly. If axle
shaft binds, use slide hammer with puller to remove.
2) Remove "O" ring and shims for preloading wheel bearing (if\
equipped). Retain shims for reassembly. To remove oil seal, use slide
hammer and hook.
3) To remove wheel bearing, straighten lock washer tabs. See
Fig. 9 . Remove lock nut using spanner wrench. Remove lock washer.
Install lock nut 3 turns on axle shaft. Install Puller (MB990787-01)
to remove axle shaft from bearing case. Rotate nuts with equal force
to remove axle shaft. Remove bearing outer race using a hammer and
drift.
Fig. 9: Removing Rear Axle Bearing (Montero)
Courtesy of Mitsubishi Motor Sales of America.
Installation
1) Apply Multipurpose Grease (SAE J310) to oil seal. Install\

2) System input tests cycle each cruise control switch and
sensor. Use analog voltmeter or Multi-Use Tester (MB991341) for system\
input check. Use multi-use tester according to operating instructions
provided with tester. Connect leads of analog voltmeter between cruise
control terminal and ground terminal of self-diagnostic connector. See
Fig. 6.
3) Turn ignition on and check items No. 1-3 on INPUT CODE
CHART. See Fig. 9 0r 10. Start engine and check items No. 4 and 5 on
INPUT CODE CHART. To display results of each input check, press SET
switch while holding RESUME switch in ON position. Read codes. Codes
will display if circuit tested is okay.
1992
1) System input tests should be performed if no trouble codes
are stored when performing SELF-DIAGNOSTICS. System input tests cycle
each cruise control switch and sensor.
2) Use Multi-Use Tester (MB991341) for system input check.
Use multi-use tester according to operating instructions provided with
tester. Connect leads of analog voltmeter between cruise control
terminal and ground terminal of self-diagnostic connector. See Fig. 6.
Turn ignition switch to ON position. Follow INPUT CODE CHART sequence.
See Fig. 9 or 10.
3) To display results of input check, move SET switch to ON
position. Then turn MAIN switch to ON position. Within one second,
activate RESUME switch. Codes will display if circuit tested is okay.
Fig. 9: 1991 Input Code Chart
Courtesy of Mitsubishi Motor Co.

Colt, Colt 200, Mirage & Summit
Remove defogger relay located to the right of fuse block.
Ground relay terminal No. 4, and apply battery voltage to terminal No.
2. Check relay continuity using ohmmeter. Continuity should exist
between terminals No. 1 and 3. With voltage disconnected, continuity
should not be present between terminals No. 1 and 3. Ensure continuity
is present between terminals No. 2 and 4. See Fig. 2.
Colt Vista, Eclipse, Stealth & 3000GT
Remove defogger relay located on left center of firewall.
Ground relay terminal No. 4, and apply battery voltage to relay
terminal No. 3. Check relay continuity using ohmmeter. Ensure
continuity exists between terminals No. 1 and 2. With voltage
disconnected, continuity should not exist between terminals No. 1 and
2. Continuity should exist between terminals No. 3 and 4. See Fig. 2.
Galant
Remove defogger relay located in right front corner of engine
compartment. Ground relay terminal No. 1, and apply battery voltage to
terminal No. 3. Check relay continuity using ohmmeter. Continuity
should exist between terminals No. 4 and 5. See Fig. 2. With voltage
disconnected, continuity should not exist between terminals No. 4 and
5. Ensure continuity exists between terminals No. 1 and 3. See Fig. 2.
Fig. 2: Identifying Defogger Relay Terminals
Courtesy of Chrysler Motors.
DEFOGGER TIMER TEST