JLG 680S, Service And Maintenance Manual

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SECTION 3 - CHASSIS & TURNTABLE
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Fuel System Checks Check for Rich or Lean symptom that causes the condition. Drive the vehicle at the speed of the complaint. Monitoring the oxygen sensors will
help identify the problem.
Check the fuel pressure while the condition exists. Refer to LPG Fuel System Diagnosis.
Verify proper fuel control solenoid operation.
Verify that the LPG manual shut-off valve is fully open.
Check the in-line fuel filter for restrictions.
Ignition System Checks Check for the proper ignition output voltage using the spark tester J26792 or the equivalent.
Verify that the spark plugs are correct for use with LPG (R42LTS).
Check the spark plugs. Remove the plugs and inspect them for the following conditions:
- Wet plugs
- Cracks
- Wear
- Improper gap
- Burned electrodes
- Heavy deposits
Check the Crankshaft Position (CKP) sensor
Additional Check Check the ECM grounds for being clean, tight, and in their proper locations.
Check the generator output voltage.
Check the vacuum hoses for kinks or leaks.
Check Transmission.
Table 3-13. Symptom Diagnosis
Checks Action