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Home >> GMC >> 1991 >> Value Van 7.4 N >> Repair and Diagnosis >> External Pages >> Different car >> Section 31 (Engine Controls - Tests W/Codes - 3.3L CNG) >> Fuel Pressure Release >> Fuel Tube Purging

Fuel Tube Purging

WARNING: This page is about a different car, the 1995 Plymouth Voyager, 1995 Plymouth Grand Voyager, 1995 Dodge Grand Caravan, and 1995 Dodge Caravan. However, it is still accessible from the selected car via links, so may be relevant.
  1. Close control valve (clockwise) on side mounted fuel cylinder. Close control valves (clockwise) on rear mounted fuel cylinders. Open manual shutoff valve.
  2. Start and operate engine until it runs out of fuel. Attempt 3 more engine starts. If check valve or fuel fill receptacle is to be serviced, slowly loosen inlet side of fuel fill tube fitting at check valve. It is normal for approximately 25 psi of natural gas pressure to flow from loosened fitting. At this point, all fuel tubes are purged of natural gas between fuel cylinders and engine. It is now okay to open fuel system for repair.
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