79
INTERMITTENT PROBLEMS
Intermittent fuel system problems can prove to be the most challenging to repair. It is most important to
remember when looking to find the cause of these problems, to operate the system in the condition when
and where the problem occurs. An example of this would be, if the DST showed a lean fuel mixture at full
load, one of the first things to look at would be the fuel pressure. The fuel pressure would need to be
monitored while the machine is operating at full load, not at idle because the leaning effect does not oc-
cur at idle. Electrical problems should be treated the same way. One excellent tool for finding
intermittent electrical problems is the DST plot/log function. Set up the plot for the code that sets. An ex-
ample of this would be if an intermittent IAT code set, tag the IAT voltage and watch the plot. While
watching the plot, agitate the electrical wire connection at the sensor and ECM connector. The resolution
of the plot screen is such that you will be able to see any unstable voltages that you would otherwise not
see with a standard DVOM.
Caution should be used when pressure washing the under hood of any electrical system. Avoid direct
pressure spray on the system electrical connectors. They are splash proof, but if water is sprayed direct-
ly at the connector moisture can become trapped behind the connector seal and cause serious system
problems.
Extra care must be taken when probing electrical pins and terminals. Do not bend or spread these ter-
minals as this can also be a source of intermittent problems cause by improper handling of these
connectors.
Summary of Contents for 3.0L GM
Page 4: ...4 ...
Page 5: ...5 General Information ...
Page 9: ...9 Maintenance ...
Page 16: ...16 ...
Page 17: ...17 LPG Fuel System ...
Page 18: ...18 LPG FUEL SYSTEM OPERATION ...
Page 25: ...25 LPG Closed Loop Schematic ...
Page 26: ...26 ...
Page 27: ...27 LPG System Diagnosis ...
Page 35: ...35 Fuel Symptom Diagnostics ...
Page 51: ...51 Electrical Section ...
Page 52: ...52 ...
Page 53: ...53 DST Diagnostic Scan Tool ...
Page 59: ...59 Select the USB button then click the OK box Click on the Search attached device box ...
Page 67: ...67 When connected the live data stream appears in the Value column ...
Page 78: ...78 ...
Page 80: ...80 ...
Page 81: ...81 Engine Wire Schematic ...
Page 82: ...82 2011 3 0L GM Engine IMPCO Emission Certified LPG Fuel System ...
Page 83: ...83 ...
Page 84: ...84 ...
Page 85: ...85 Engine Wire Harness Repair ...
Page 89: ...89 Diagnostic Trouble Codes DTCs ...
Page 93: ...93 ...
Page 101: ...101 ...
Page 105: ...105 ...
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Page 119: ...119 ...
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Page 217: ...217 ...
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Page 225: ...225 ...
Page 229: ...229 ...
Page 237: ...237 Servicing the Fuel System ...
Page 254: ...254 ...
Page 255: ...255 LPG Parts Diagram ...
Page 256: ...256 THROTTLE BODY ASSEMBLY ...
Page 258: ...258 FUEL RAIL INJECTORS ...
Page 260: ...260 REGULATOR ASSEMBLY ...
Page 262: ...262 HOSE ASSEMBLIES COOLANT VACUUM FUEL ...
Page 264: ...264 THERMOSTAT HOUSING ...
Page 266: ...266 ENGINE CONTROL MODULE ...
Page 267: ...267 ENGINE CONTROL MODULE Item Description Qty IMPCO Part Number 1 ECM Liugong 1 A11 173 ...
Page 268: ...268 SENSORS 4 1 3 6 5 2 7 ...
Page 270: ...270 DISTRIBUTOR ...
Page 272: ...272 FUSE BOX BRACKET ...
Page 274: ...274 IGNITION COIL ...
Page 275: ...275 IGNITION COIL Item Description Qty Part Number 1 Coil Ignition 1 7245530 ...
Page 276: ...276 MANIFOLDS ...
Page 278: ...278 WIRE HARNESS FUSES FUSE BOX COVER Fuse Box Layout 4 ...
Page 280: ...280 PCV VENT VALVE ...
Page 282: ...282 MISCELLANEOUS ENGINE ...
Page 284: ...284 ALTERNATOR ...
Page 286: ...286 STARTER ...
Page 291: ...291 ...
Page 292: ...292 3 0L UPPER ...
Page 294: ...294 3 0L LOWER ...
Page 298: ...298 ...
Page 299: ...299 Labor Time Guide ...
Page 317: ...317 Definitions ...
Page 322: ...322 ...
Page 323: ...323 Appendix ...
Page 327: ...327 DTC SPN FMI Chart ...