SERVICE MANUAL NUMBER 23 FUEL INJECTION...

5D

SERVICE MANUAL NUMBER 23 FUEL INJECTION SYSTEM TROUBLESHOOTING

Page 5D-190-861326--1 MARCH 1999

FUEL SYSTEMSection 5D - Fuel Injection System Troubleshooting

Table of Contents

Troubleshooting 5D-2. . . . . . . . . . . . . . . . . . . . . Diagnostic Trouble Codes for the MEFI 1 454 / 502 Mag MPI and 8.2L MPI Engines 5D-2. . . . . . . . . . . . . . . Diagnostic Trouble Codes for the MEFI 2 7.4L MPI Engines 5D-2. . . . . . . . Diagnostic Trouble Codes for the MEFI 3 454 cid (7.4L)/502 cid (8.2L) Engines 5D-3. . . . . . . . . . . . . . . . . . Scan Tool Normal Specifications (Idle / Warm Engine / Closed Throttle / Neutral) 5D-5. . . . . . . . . . . . . . . . . . . . . . . . Important Preliminary Checks 5D-6. . . . . .

Visual/Physical Check 5D-6. . . . . . . . . . . . . Hard Start Symptom 5D-8. . . . . . . . . . . . . . Surges and/or Chuggles Symptom 5D-11. . Lack of Power, Sluggish or Spongy Symptom 5D-13. . . . . . . . . . . . . . . . . . . . . . . Detonation/Spark Knock Symptom 5D-16. . Hesitation, Sag, Stumble Symptom 5D-19. Cuts Out, Misses Symptom 5D-21. . . . . . . . Rough, Unstable, or Incorrect Idle, Stalling Symptom 5D-23. . . . . . . . . . . . . . . . Poor Fuel Economy Symptom 5D-27. . . . . . Dieseling, Run-On Symptom 5D-29. . . . . . . Backfire Symptom 5D-30. . . . . . . . . . . . . . . .

FUEL INJECTION SYSTEM TROUBLESHOOTING SERVICE MANUAL NUMBER 23

Page 5D-2 90-861326--1 MARCH 1999

Troubleshooting

Diagnostic Trouble Codes for the MEFI 1 454 / 502 Mag MPI and 8.2L MPIEngines

Code Number Code Description

Code 14 (ECT) Engine Coolant Temperature

Code 21 (TP) Throttle Position Sensor

Code 23 (IAT) Intake Air Temperature

Code 33 (MAP) Manifold Absolute Pressure

Code 42 (IC) Ignition Control

Code 43 (KS) Knock Sensor

Code 51 Calibration Memory Failure

Diagnostic Trouble Codes for the MEFI 2 7.4L MPI Engines

Code Number Code Description

Code 14 (ECT) Engine Coolant Temperature - Low Temperature Indicated

Code 15 (ECT) Engine Coolant Temperature - High Temperature Indicated

Code 21 (TP) Throttle Position Sensor - Signal Voltage High

Code 22 (TP) Throttle Position Sensor - Signal Voltage Low

Code 23 (IAT) Intake Air Temperature - Low Temperature Indicated

Code 25 (IAT) Intake Air Temperature - High Temperature Indicated

Code 33 (MAP) Manifold Absolute Pressure - Signal Voltage High

Code34 (MAP) Manifold Absolute Pressure - Signal Voltage Low

Code 41 (IC) Ignition Control - Open IC Circuit

Code 42 (IC) Ignition Control - Grounded IC Circuit, Open or GroundedBypass

Code 43 (KS) Knock Sensor - Continuous Knock Detected

Code 44 (KS) Knock Sensor - No Knock Detected

Code 51 (ECM) Calibration Memory Failure

Code 52 (ECM) EEPROM Failure


Page 5D-390-861326--1 MARCH 1999

Diagnostic Trouble Codes for the MEFI 3 454 cid (7.4L) / 502 cid (8.2L) Engines

CodeNumber Connection Conditions Comments

14 ECT highMinimum run time (10 sec)

Sensor output high (cold) > 240counts

Open circuit

Faulty sensor

15 ECT lowMinimum run time (10 sec) sensor

Sensor output low (hot) < 7 counts

Short circuit

Faulty sensor

21 TPS high

Sensor output high (> 250 counts)anytime or, skewed high ( > 70) @ < 700 rpm and < 70 kpa for at least5 seconds

Open circuit,

WOT Faulty sensor

No referenceground

22 TPS low Sensor output low (< 4 counts)anytime

Short circuit

Faulty sensor

No referencevoltage

23 MAT highMinimum run time (10 sec)

Sensor output high (cold) > 253counts

Open circuit

Faulty sensor

25 MAT lowMinimum run time (10 sec) sensor

Sensor output low (hot) < 7 counts

Short circuit

Faulty sensor

33 MAP high kpa > 80 and tps < 5% and rpm >500 for at least 5 seconds

Open circuit

Faulty sensor

No Referenceground

34 MAP low kpa < 14 and tps > 5% and rpm<300 for at least 0.5 seconds

Short circuit

Faulty sensor

No referencevoltage

41 EST open (GMdistributor only)

Ignore first 20 spark events requires10 faults to set code

Open circuit

Faulty ignitionmodule

42 EST grounded Ignore first 20 spark events requires10 faults to set code

Short circuit

Faulty referencepickup

43 Continuousknock

Must have continuous knock retardfor at least 30 seconds

Incorrect basetiming

Faulty knock sensor

44 No knockAfter 513 tdc knock free events, rpm> 3000 and MAP > 70 and filteredsensor noise < 0.14 volts

Disconnectedsensor

Broken/open circuit

Faulty knock sensor


Page 5D-4 90-861326--1 MARCH 1999

Diagnostic Trouble Codes for the MEFI 3 454 cid (7.4L) / 502 cid (8.2L) Engines(continued)

CodeNumber Connection Conditions Comments

45 Coil driver fault Ignore first 20 spark events requires8 faults to set code

Open secondarywire

Open primary cable

51 Checksum error Reserved - Invalid ECM checksum Bad ECM

61 Fuel pressurehigh

Minimum run time (10 sec)

Sensor output high (> 4.9 volts)

Open circuit

Faulty sensor

Bad/wrong regulator

62 Fuel pressurelow

Minimum run time (10 sec)

Sensor output low (< 0.1 volts)

Short circuit

Faulty sensor

No fuel pump power


Page 5D-590-861326--1 MARCH 1999

Scan Tool Normal Specifications (Idle / Warm Engine / Closed Throttle /Neutral)

SCAN POSITION UNITS DISPLAYED TYPICAL DATA VALUE

rpm rpm 600-700 rpm

Desired rpm rpm 600 rpm

Coolant Temp. ° F(° C) 150-170° F (66-77° C)

Manifold Air Temp. ° F (° C) Varies with Ambient Tempera-ture

Throttle Position Volts .4 to .8 Volts

Throttle Angle 0-100 % 0-1%

MAP Volts or kPa1-3 Volts or (45-55 kPa) (De-pends on Vacuum and BaroPressure)

Baro Volts or kPa 3-5 Volts (Depends on Altitudeand Barometric Pressure)

Bat Volts 12.0-14.5 Volts

Spark Advance Degrees -10 to 30°

Knock Retard Degrees 0°

Idle Air Control IAC Counts (Steps) 0-40 Counts

Minimum IAC Position Counts (Steps) 0-40 Counts

Idle Air Control Follower Counts (Steps) 0 Counts

Injector Pulse Width msec. 2-3 msec.

Injector On Time Cranking msec. 2.5-3.5 msec. (Depends onWater/Air Temperature)

Fuel Consumption GPH (L/h) 1-2 GPH (3.7-7.5 L/h)

Time From Start 0:00:00-1092:00 Varies

Memory Calibration CheckSum

Calibration and Check Sum Varies with Software revisionin ECM

Oil Press/IO Level (See Note) OK/LO OK

Engine Overtemp OK/Overheating OK

Lanyard Stop Mode OFF/ON OFF

NOTE: MCM will read I/O Level and MIE will read Trans.


Page 5D-6 90-861326--1 MARCH 1999

Important Preliminary Checks

BEFORE STARTING

Before using this section you should have performed the “On-Board Diagnostic (OBD) Sys-tem Check” in in the “General System Diagnostics” section and determined that:

• The ECM and/or MIL (Malfunction Indicator Lamp) are operating correctly.

• There are no DTC(s) stored.

Verify the customer complaint and locate the correct symptom in the table of contents.Check the items indicated under that symptom.

Visual/Physical CheckSeveral of the symptom procedures call for a careful Visual/ Physical Check. The impor-tance of this step cannot be stressed too strongly. It can lead to correcting a problem withoutfurther checks and can save valuable time. This check should include:

• ECM grounds and sensor connections for being clean, tight and in their proper location.

• Vacuum hoses for splits, kinks and proper connections. Check thoroughly for any type ofleak or restriction.

• Air leaks at throttle body mounting area and intake manifold sealing surfaces.

• Ignition wires for cracking, hardness, proper routing and carbon tracking.

• Wiring for proper connections, pinches and cuts. If wiring harness or connector repair isnecessary, refer to “Description and System Operation” section for correct procedure.

• Moisture in primary or secondary ignition circuit connections.

• Salt corrosion on electrical connections and exposed throttle body linkages.

INTERMITTENTS

IMPORTANT: Problem may or may not turn ON the Malfunction Indicator Lamp (MIL)or store a DTC. DO NOT use the Diagnostic Trouble Code (DTC) tables for intermittentproblems. The fault must be present to locate the problem.

Most intermittent problems are caused by faulty electrical connections or wiring. Performcareful visual/physical check. Check for the following conditions:

• Poor mating of the connector halves, or a terminal not fully seated in the connector body(backed out or loose).

• Improperly formed or damaged terminals and/or connectors.

All connector terminals in the problem circuit should be carefully checked for proper contacttension.

• Poor terminal to wire connection (crimping). This requires removing the terminal fromthe connector body to check. Refer to “Wiring Harness Service” in the “Description andSystem Operation” section.

The vessel may be driven with a Digital Multimeter connected to a suspected circuit. Anabnormal voltage when malfunction occurs is a good indication that there is a fault in thecircuit being monitored.


Page 5D-790-861326--1 MARCH 1999

A scan tool can be used to help detect intermittent conditions. The scan tool has severalfeatures that can be used to locate an intermittent condition. The following features can beused in finding an intermittent fault:

The “Record” feature (if equipped) can be triggered to capture and store engine parameterswithin the scan tool when the malfunction occurs. This stored information then can bereviewed by the service technician to see what caused the malfunction.

To check loss of DTC memory, disconnect TP sensor and idle engine until the MIL comesON. A trouble code should be stored and kept in memory when ignition is turned OFF. If notthe ECM is faulty. When this test is completed, make sure that you clear the DTC 22 frommemory.

An intermittent MIL with no stored DTC may be caused by the following:

• Ignition coil shorted to ground and arcing at ignition wires or plugs.

• MIL wire to ECM shorted to ground.

• Poor ECM grounds, Go to ECM wiring diagrams.

• Check for an electrical system interference caused by a sharp electrical surge. Normally,the problem will occur when the faulty component is operated.

• Check for improper installation of electrical options such as lights, ship to shore radios,sonar, etc.

• Check that knock sensor wires are routed away from spark plug wires, ignition systemcomponents and charging system components.

• Check for secondary ignition components shorted to ground, or an open ignition coilground (coil mounting brackets).

• Check for components internally shorted to ground such as starters, alternators orrelays.

All Ignition Control (IC) module wiring should kept away from the alternator. Check all wiresfrom the ECM to the ignition control module for poor connections.


Page 5D-8 90-861326--1 MARCH 1999

Hard Start SymptomStep Action Value(s) Yes No

Definition: Engine cranks OK, but does not start for a long time. Does eventually run, ormay start but immediately dies.

1 Was the “On-Board Diagnostic” (OBD)System Check performed? - Go to Step 2

Go to OBDSystem Check

2

Check to see if the driver is using thecorrect starting procedure as describedin the owners manual. Educate thedriver if they do not know.

Does the driver know the correct start-ing procedure? - Go to Step 3

System nor-mal

3Was visual/physical check performed?

- Go to Step 4

Go to Visual/PhysicalCheck

4

1. Check for proper operation of fuelpump relay circuit.

• Refer to Table A-5 in “General Sys-tem Diagnostics” section.

2. If a problem is found, repair as nec-essary.

Was a problem found? -

Go to OBDSystemCheck Go to Step 5

5

1. Check for contaminated fuel.2. Check water separating fuel filter.3. If a problem is found, repair as nec-

essary.Was a problem found? -


6

1. Check for proper fuel pressure.• Refer to Table A-4 in “General Sys-

tem Diagnostics” section.2. If a problem is found, repair as nec-



7

1. Check for proper ignition voltageoutput.





8 Is a scan tool being used?-

Go to Step10 Go to Step 9


Page 5D-990-861326--1 MARCH 1999

Hard Start Symptom (Continued)

9

1. Check for a ECT sensor shifted invalue.

2. With engine completely cool, mea-sure the resistance of the ECT sen-sor.

3. Refer to the Engine Coolant Tem-perature Sensor Temperature -vs-Resistance value table on the facingpage of DTC 14 in the “Trouble CodeDiagnostics” section. Compare theapproximate temperature of theECT sensor to an accurate readingof ambient air temperature.

Are the readings within the specifiedvalue?

10° F(-12° C)


10

1. Check ECT sensor for being shiftedin value.

2. With the engine completely cool,compare the ECT sensor tempera-ture with an accurate reading ofambient air temperature.

Are the temperatures within thespecified value of each other?

10° F(-12° C)


11

1. Using a scan tool, display ECT sen-sor temperature and note value.

2. Check resistance of ECT sensor.3. Go to Engine Coolant Temperature

Sensor Temperature -vs- Resis-tance value table on the facing pageof DTC 14 in the Diagnostics sec-tion.

Is resistance value of ECT sensor nearthe resistance of the value noted? -


12

Locate and repair high resistance orpoor connection in the ECT signalcircuit or the ECT sensor ground.Is action complete? -

Go to OBDSystemCheck -

13Replace the ECT sensor.Is action complete?

-

Go to OBDSystemCheck -

14

1. Check for intermittent opens orshorts to ground in the MAP sensorcircuits.





Page 5D-10 90-861326--1 MARCH 1999

Hard Start Symptom (Continued)

15

1. Check for proper operation of the TPsensor.

2. Check or throttle linkage sticking,binding or worn causing TP sensorvoltage to be higher than normal.




16

1. Check for proper operation of theIAC valve.





17

1. Check or the following EngineMechanical problems:

• Low compression.• Leaking cylinder head gaskets.• Worn or incorrect camshaft.• Proper valve timing/valve train prob-

lem.• Restricted exhaust system.




18

1. Review all diagnostic procedureswithin this table.

2. If all procedures have been com-pleted and no malfunctions havebeen found, review/inspect the fol-lowing:

• Visual/physical inspection.• Scan tool data.• All electrical connections within a

suspected circuit and/or system.3. If a problem is found, repair as nec-


Go to OBDSystemCheck

ContactMerCruiserCustomerService


Page 5D-1190-861326--1 MARCH 1999

Surges and/or Chuggles SymptomStep Action Value(s) Yes No

Definition: Engine power variation under steady throttle or cruise. Feels like the enginespeeds up and slows down with no change in the throttle lever position.




- Go to Step 3


3

1. Check for engine going into rpmreduction mode.

2. If a problem is found, repair asnecessary.


NotApplicable

toMerCruiserEFI or MPI Go to Step 4

4

1. Check for contaminated fuel.2. Check fuel filters and water

separator.3. If a problem is found, repair as

necessary.Was a problem found? -


5

1. Check for proper fuel pressure whilethe condition exists.





6

1. Check for intermittent opens or shortto grounds in the ECT sensor, MAPsensor and TP sensor circuits. Alsocheck or throttle linkage sticking,binding or worn.

2. An intermittent failure may not storea DTC.




7






8

1. Check ignition coil for cracks orcarbon tracking.





Page 5D-12 90-861326--1 MARCH 1999

Surges and/or Chuggles Symptom (Continued)

9

1. Check integrity of the primary andsecondary wiring.

2. Check routing of the wiring.3. Check condition of IC module,

pick-up coil, distributor cap, rotorand spark plug wires.




10

1. Remove spark plugs and check forwet plugs. cracks, wear, impropergap, burned electrodes or heavydeposits.

• Refer to Distributor Ignition Systemin “Description and System Opera-tion” section.

NOTE: If park plugs are gas or oil fouled,the cause of the fouling must be deter-mined before replacing the spark plugs.2. If a problem is found, repair as



11

1. Check fuel delivery system itemsthat can cause the engine to run rich.




12

1. Check fuel delivery system itemsthat can cause the engine to runlean.




13

1. Check the injector connections forproper mating.

2. If any of the injectors connectors areconnected to an incorrect cylinder,correct as necessary.



14

1. Check ECM grounds for beingclean, tight and in the properlocations.





Page 5D-1390-861326--1 MARCH 1999

Surges and/or Chuggles Symptom (Continued)

15

1. Visually/physically check vacuumhoses for splits, kinks and properconnections and routing.




16

1. Check or proper alternator voltageoutput.

2. The voltage should be betweenspecified values.


Was a problem found?11-16Volts


17


2. If all procedures have beencompleted and no malfunctionshave been found, review/inspect thefollowing:


suspected circuit and/or system.3. If a problem is found, repair as




Lack of Power, Sluggish or Spongy SymptomStep Action Value(s) Yes No

Definition: Engine delivers less than expected power. Little or no increase in speed whenthrottle lever is advanced part way.



2

Compare engine performance with asimilar engine. Both should be close.Is engine performance close to similarengine. -

No problemfound Go to Step 3


- Go to Step 4


4

1. Remove and check flame arrestorfor dirt, or for being restricted.

2. Replace flame arrestor if necessary.Was a problem found? -


5

1. Check for contaminated fuel.2. Check water separating fuel filter.3. If a problem is found, repair as




Page 5D-14 90-861326--1 MARCH 1999

Lack of Power, Sluggish or Spongy Symptom (Continued)

6






7

1. Check for injector driver CKT’s 467or 468 for an open.




8

1. Check for proper operation ofIgnition Control (IC) circuit nd theKnock Sensor (KS) circuit.




9






10

1. Remove spark plugs, check for wetplugs, cracks, wear, improper gap,burned electrodes or heavydeposits.

• Refer to “Distributor Ignition Sys-tem” in “Description and System Op-eration” section.

NOTE: If park plugs are gas or oil fouled,the cause of the fouling must be deter-mined before replacing the spark plugs.




11

1. Check ignition coil for cracks orcarbon tracking.





Page 5D-1590-861326--1 MARCH 1999


12






13

1. Check ECM grounds for beingclean, tight and in their properlocations.




14




NotApplicable

toMerCruiserEFI or MPI Go to Step 15

15

1. Check diagnostic test CKT 451 forbeing shorted to ground. This willcause the rpm to be lowered.




16


2. The voltage should be betweenspecified values.




17

1. Check for the following EngineMechanical problems:

• Low compression.• Leaking cylinder head gaskets.• Worn or incorrect camshaft.• Proper valve timing/valve train prob-

lem.• Restricted exhaust system.





Page 5D-16 90-861326--1 MARCH 1999


18

1. Check for excessive resistance onthe bottom of the boat such as dirt,barnacles, etc.

2. Check for proper propeller size andpitch for that application.




19


2. When all procedures have beencompleted and no malfunctions arefound, review/inspect the following:

• Visual/physical inspection.• Scan tool data.• All connections within a suspected

circuit and/or system.3. If a problem is found, repair as nec-




Detonation/Spark Knock SymptomStep Action Value(s) Yes No

Definition: A mild to severe ping, usually worse under acceleration. The engine makessharp metallic knocks that change with throttle opening.




- Go to Step 3


3

1. Check base timing.• Refer to Ignition Timing Set Proce-

dure in the Distributor Ignition sec-tion.




4

1. Check for proper operation ofIgnition Control (IC) circuit and theKnock Sensor (KS) circuit.





Page 5D-1790-861326--1 MARCH 1999

Detonation/Spark Knock Symptom (Continued)

5

1. Check for good ignition systemground.

2. Check spark plugs for proper gapand heat range.




6

1. Check for contaminated fuel.2. Check for poor fuel quality and

proper octane rating.3. If a problem is found, repair as



7


tem Diagnostics” section.2. If a problem is found, repair as



8 Is a scan tool being used? - Go to Step 9 Go to Step 10

9

If scan tool readings are normal (Referto “Scan Tool Normal Specifications” inthis section) and there are no enginemechanical faults, fill fuel tank with aknown high quality gasoline.Is detonation present? -

Go to Step10


10

1. Check for obvious overheatingproblems:

• Loose water pump belt.• Faulty or incorrect water pump.• Restriction in cooling system.• Faulty or incorrect thermostat.




11

1. Check fuel delivery system itemsthat can cause an engine to run lean.





Page 5D-18 90-861326--1 MARCH 1999

Detonation/Spark Knock Symptom (Continued)

12

1. Check for ECT sensor being shiftedin value.

2. Check for proper output voltage ofthe TP sensor at closed throttle andwide open throttle. Also checkthrottle linkage for sticking, bindingor worn.




13

1. Check for the following EngineMechanical problems:

• Low compression.• Low oil level.• Excessive oil in the combustion

chambers due to valve seals leak-ing.

• Worn or incorrect camshaft.• Proper valve timing/valve train prob-

lem.• Combustion chambers for exces-

sive carbon build up.2. If a problem is found, repair as nec-



14

1. Remove excessive carbon buildupwith a top engine cleaner.

• Refer to instructions on top enginecleaner can.

2. Re-evaluate engine performance. Isdetonation still present? -

Go to Step15


15









Page 5D-1990-861326--1 MARCH 1999

Hesitation, Sag, Stumble SymptomStep Action Value(s) Yes No

Definition: Momentary lack of response as the throttle lever is advanced. Can occur atall engine speeds. Usually most severe when first starting out. May cause engine to stallif severe enough.




- Go to Step 3


3




4

1. Check or proper fuel pressure whilethe condition exists.





5

1. Check fuel injectors.• Refer to Injector Balance Test in

“Test General System Diagnostics”section.




6

1. Check for proper operation of Igni-tion Control (IC) circuit and theKnock Sensor (KS) circuit.




7








Page 5D-20 90-861326--1 MARCH 1999

Hesitation, Sag, Stumble Symptom (Continued)

8

1. Remove spark plugs and check forwet plugs, cracks. wear, impropergap, burned electrodes or heavydeposits.

• Refer to Distributor Ignition System.


2. If a problem is found, repair as nec-essary



9

1. Check for the ECT sensor shifted invalue.






10




NotApplicable

to MerCruis-er

EFI or MPI Go to Step 11

11

1. Check for proper alternator voltageoutput.

2. The voltage should be between spe-cified values.




12

1. Check for faulty or incorrect thermo-stat.




13

1. Check intake valves for valvedeposits.

2. If deposits are found, remove asnecessary.

Were deposits found on the intakevalves? -



Page 5D-2190-861326--1 MARCH 1999

Hesitation, Sag, Stumble Symptom (Continued)

14





essary.




Cuts Out, Misses SymptomStep Action Value(s) Yes No

Definition: Steady pulsation or jerking that follows engine speed, usually morepronounced as engine load increases. The exhaust has a steady spitting sound at idle,low speed or on hard acceleration for fuel starvation that can cause engine to cut out.




- Go to Step 3


3




4






5

1. Disconnect all injector harness con-nectors and install an injector testlight J 34730-2 between the harnessterminal connector of each injector.

2. Crank engine and note light on eachconnector. If test light fails to blink atany one of the connectors, it is afaulty injector drive circuit harness,connector or terminal.





Page 5D-22 90-861326--1 MARCH 1999

Cuts Out, Misses Symptom (Continued)

6


“General System Diagnostics” sec-tion.




7

1. Check for proper spark at each cylin-der.




8

1. Check the spark plugs for the follow-ing:

• Insulator cracks.• Improper gap.• Burned electrodes.• Heavy deposits.

NOTE: If spark plugs are gas or oilfouled, the cause of the fouling must bedetermined before replacing the sparkplugs.2. If a problem is found, repair as nec-

essaryWas a problem found? -


9

1. Check engine mechanical for the fol-lowing conditions.

• Low compression.• Sticking or leaking valves.• Bent push rods• Worn rocker arms.• Broken valve springs.• Worn camshaft lobe(s).• Incorrect valve timing.




10

1. Check Intake and exhaust man-ifold(s) for casting flash.





Page 5D-2390-861326--1 MARCH 1999

Cuts Out, Misses Symptom (Continued)

11

1. Check for Electromagnetic Interfer-ence (EMI). A missing condition canbe caused by EMI on the referencecircuit. EMI can usually be detectedby monitoring engine rpm with ascan tool or tachometer. A suddenincrease in rpm with little change inactual engine rpm change, indicatesEMI is present.

2. If EMI is present, locate and repairthe source.



12





essary.




Rough, Unstable, or Incorrect Idle, Stalling SymptomStep Action Value(s) Yes No

Definition: Engine runs unevenly at idle. If severe, the engine or vessel may shake.Engine idle speed may vary in rpm. Either condition may be severe enough to stall theengine.




- Go to Step 3


3

1. Check for proper operation of theIAC valve.





4






Page 5D-24 90-861326--1 MARCH 1999

Rough, Unstable, or Incorrect Idle, Stalling Symptom (Continued)

5







6

1. Check ignition coil for cracks or car-bon tracking.




7

1. Remove spark plugs, check for wetplugs, cracks, wear, improper gap,burned electrodes or heavy depos-its.






8

Check the injector connections. If any ofthe injectors are connected to anincorrect cylinder, correct as necessary.Was a problem found? -


9

1. Disconnect all injector harness con-nectors and install an injector testlight J 34730-2 between the harnessterminal connector of each injector.

2. Crank engine and note light on eachconnector. If test light fails to blink atany one of the connectors, it is afaulty injector drive circuit harness,connector or terminal.




10







Page 5D-2590-861326--1 MARCH 1999


11

1. Check for fuel in pressure regulatorvacuum hose.

2. If fuel is present, replace the fuelpressure regulator assembly.

• Refer to Fuel Metering System in“Description and System Operation”section.




12






13

1. Check ECM grounds for beingclean, tight and in their proper loca-tions.

2. Also check that battery cables andground straps are clean nd secure.




14

1. Check fuel delivery system itemsthat can cause the engine to run rich.




15

1. Check fuel delivery system itemsthat can cause the engine to runlean.




16


2. The voltage should be between spe-cified values.





Page 5D-26 90-861326--1 MARCH 1999


17

1. Check the following EngineMechanical items:

• Check compression.• Sticking or leaking valves.• Worn camshaft lobe(s).• Valve timing.• Broken valve springs.




18

1. Check intake valves for valvedeposits.

2. If deposits are found, remove asnecessary.

Were deposits found on the intakevalves? -


19

1. Check for faulty motor mounts.2. If a problem is found, repair as nec-



20









Page 5D-2790-861326--1 MARCH 1999

Poor Fuel Economy SymptomStep Action Value(s) Yes No

Definition: Fuel economy is noticeably lower than expected. Also, economy is noticeablylower than it was on this engine at one time.




- Go to Step 3


3

1. Check operators driving habits. Areexcessively heavy loads being car-ried? Is operator accelerating toomuch, too often?


Was a problem found? -System nor-

mal Go to Step 4

4

1. Check flame arrestor for dirt or beingplugged.

2. Check for fuel leaks.3. If a problem is found, repair as nec-



5





6





7



NOTE: If spark plugs are gas or oilfouled, the cause of the fouling must bedetermined before replacing the sparkplugs.





Page 5D-28 90-861326--1 MARCH 1999

Poor Fuel Economy Symptom (Continued)

8

1. Visual (physically) check vacuumhoses for splits, kinks and improperconnections and routing.


Was a repair required? -


9

1. Check engine compression forbeing low.




10

1. Check exhaust system for possiblerestriction.

2. Inspect exhaust system for dam-aged or collapsed pipes.




11

1. Check for excessive resistance onthe bottom of the boat such as dirt,barnacles, etc.

2. Check for proper propeller size andpitch for that application.




12


2. When all procedures have beencompleted and no malfunctions arefound, review/inspect the following:

• Visual/physical inspection.• Scan tool data.• All connections within a suspected

circuit and/or system.3. If a problem is found, repair as nec-

essary.





Page 5D-2990-861326--1 MARCH 1999

Dieseling, Run-On SymptomStep Action Value(s) Yes No

Definition: Engine continues to run after key is turned “OFF,” but runs very rough. Ifengine runs smooth, check ignition switch and adjustment.




- Go to Step 3


3

1. Check for leaking fuel injectors.• Refer to Table A-4 in “General Sys-




4





5

1. Check for obvious overheatingproblems:

• Loose water pump belt.• Faulty or incorrect water pump.• Restriction in cooling system.• Faulty or incorrect thermostat.




6

1. Check for proper operation of theEFI system relay.






Page 5D-30 90-861326--1 MARCH 1999

Dieseling, Run-On Symptom (Continued)

7



• Visual physical inspection.• Scan tool data.• All electrical connections within

a suspected circuit and/or sys-tem.





Backfire SymptomStep Action Value(s) Yes No

Definition: Fuel ignites in the intake manifold, or in the exhaust system, making loudpopping noise.




- Go to Step 3


3

1. Check flame arrestor for properinstallation.




4





5

Check the injector connections. If any ofthe injectors are connected to anincorrect cylinder, correct as necessary.Was a problem found? -


6







Page 5D-3190-861326--1 MARCH 1999

Backfire Symptom (Continued)

7





8







9

1. Check ignition coil for cracks or car-bon tracking.




10

1. Check for proper ignition voltageinput to the ECM.

2. Check for intermittent open or shortto ground on the ignition voltageinput circuit to the ECM.




11


• Refer to Distributor Ignition Systemin “Description and System Opera-tion” section.

NOTE: If park plugs are gas or oil fouled,the cause of the fouling must be deter-mined before replacing the spark plugs





Page 5D-32 90-861326--1 MARCH 1999

Backfire Symptom (Continued)

12

1. Check for intermittent opens or shortto grounds in the MAP sensor andTP sensor circuits. Also check forthrottle linkage sticking, binding orworn.





13

1. Check engine mechanical for the fol-lowing conditions:

• Low compression.• Sticking or leaking valves.• Worn camshaft lobe(s).• Incorrect valve timing.




14

1. Check Intake and exhaust man-ifold(s) for casting flash.




15








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SERVICE MANUAL NUMBER 23 FUEL INJECTION...

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