MerCruiser 305 CID (5.0L) Service Manual page 14

Section 5F - Fuel Injection System Troubleshooting
Scan Tool Normal Specifications (Idle / Warm
Engine / Closed Throttle / Neutral)
Important Preliminary Checks
Before Starting . . . . . . . . . . . . . . . . . . .
Visual / Physical Check
Intermittents . . . . . . . . . . . . . . . . . . . . . . . .
Hard Start Symptom . . . . . . . . . . . . . . . . .
Surges and/or Chuggles Symptom
Lack of Power, Sluggish or
Spongy Symptom . . . . . . . . . . . . . . . . . . .
Special Tools . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Circuit Check
Scan Tool Normal Specifications
Diagnostic Trouble Codes
ECM Connector and EFI
Symptoms Chart . . . . . . . . . . . . . . . . . . . .
J-1 Circuits with MEFI 1 and MEFI 2
J-2 Circuits with MEFI 1 and MEFI 2
J-1 Circuits with MEFI 3
J-2 Circuits with MEFI 3
Wiring System Diagrams
MEFI 1 and MEFI 2
MEFI 3 . . . . . . . . . . . . . . . . . . . . . . . . . .
MEFI 3 With Mercury Distributor
MEFI 3 With GM EST Distributor
Injector Balance Test (Multi-Port Models) 5G-22
Test Procedure . . . . . . . . . . . . . . . . . . .
Test Example . . . . . . . . . . . . . . . . . . . .
General Diagnostic Tests
On-Board Diagnostic (OBD)
System Check . . . . . . . . . . . . . . . . . . .
Chart A-1 No MIL or No DLC Data
Chart A-2 MIL ON Steady -
Will Not Flash DTC 12
Chart A-3 Engine Cranks But
Will Not Run . . . . . . . . . . . . . . . . . . . . .
Chart A-4 Fuel System Diagnosis
Chart A-5 Fuel System Electrical Test 5G-34
Chart A-6 EFI System/Ignition
Relay Check . . . . . . . . . . . . . . . . . . . .
Chart A-7 Ignition System Check
Chart A-8 Idle Air Control (IAC)
Functional Test . . . . . . . . . . . . . . . . . .
Discrete Input Circuit Check -
Non-Scan Only . . . . . . . . . . . . . . . . . .
Page xii
. . . . 5F-2
. . . . . . . . . 5F-3
5F-3
. . . . . . . . . . . . 5F-3
5F-4
5F-5
. . . . 5F-7
5F-9
Section 5G - Diagnostics
5G-2
. . . . . . . . . . . . . 5G-4
. . . 5G-4
. . . . . . . . . . . . 5G-5
5G-6
5G-6
5G-8
. . . . . . . . . . . 5G-10
. . . . . . . . . . . 5G-12
. . . . . . . . . . . . . 5G-14
. . . . . . . . . . . . . . . 5G-14
5G-18
. . . . 5G-20
. . . 5G-21
5G-22
5G-23
. . . . . . . . . . . . . 5G-24
5G-24
. . 5G-26
. . . . . . . . . . . . 5G-28
5G-30
. . . 5G-32
5G-36
. . . 5G-38
5G-44
5G-46
Detonation / Spark Knock Symptom
Hesitation, Sag, Stumble Symptom
Cuts Out, Misses Symptom
Rough, Unstable, or Incorrect Idle,
Stalling Symptom . . . . . . . . . . . . . . . . . . .
Poor Fuel Economy Symptom
Dieseling, Run-On Symptom
Backfire Symptom . . . . . . . . . . . . . . . . . . .
Clearing Trouble Codes
Using Code Mate Tester
Using Scan Tool . . . . . . . . . . . . . . . . . .
Diagnostic Testing . . . . . . . . . . . . . . . . . . .
Code 14 Engine Coolant Temperature
(ECT) Sensor Circuit
Code 15 Engine Coolant Temperature
(ECT) Sensor Circuit
Code 21 Throttle Position
(TP) Sensor Circuit
Code 22 Throttle Position
(TP) Sensor Circuit
Code 23 Intake Air Temperature
(IAT) Sensor Circuit
Code 25 Intake Air Temperature
(IAT) Sensor Circuit
Code 33 Manifold Absolute Pressure
(MAP) Sensor Circuit
Code 34 Manifold Absolute Pressure
(MAP) Sensor Circuit
Code 41 Ignition Control (IC) Circuit
Code 42 Ignition Control (IC) Circuit
Code 43 Knock Sensor (KS) Circuit
Code 44 Knock Sensor (KS) Circuit
Code 45 Ignition Coil Driver Fault
Code 51 Calibration Memory Failure
Code 52 EEPROM Failure
Code 61 Fuel Pressure (FP) Circuit
Code 62 Fuel Pressure (FP)
Sensor Circuit . . . . . . . . . . . . . . . . . . .
. . . 5F-11
. . . . 5F-13
. . . . . . . . . . . 5F-15
5F-17
. . . . . . . . 5F-20
. . . . . . . . . . 5F-22
5F-23
. . . . . . . . . . . . . . 5G-52
. . . . . . . . . . . 5G-52
5G-52
5G-53
. . . . . . . . . . . . . 5G-53
. . . . . . . . . . . . . 5G-56
. . . . . . . . . . . . . . . 5G-58
. . . . . . . . . . . . . . . 5G-61
. . . . . . . . . . . . . . 5G-64
. . . . . . . . . . . . . . 5G-66
. . . . . . . . . . . . . 5G-68
. . . . . . . . . . . . . 5G-71
. 5G-74
. 5G-76
. 5G-78
. 5G-81
. . . 5G-84
5G-86
. . . . . . . . . 5G-87
. 5G-88
5G-91
90-861327--1 OCTOBER 1999