Following are vacuum diagrams for most of the engine and emissions package combinations covered by this guide. Because vacuum circuits will vary based on various engine and vehicle options, always refer first to the vehicle emission control information label, if present. Should the label be missing, or should vehicle be equipped with a different engine from the vehicle's original equipment, refer to the diagrams below for the same or similar configuration.
If you wish to obtain a replacement emissions label, most manufacturers make the labels available for purchase. The labels can usually be ordered from a local dealer.
See Figures 1 through 141
Fig. Fig. 1: Most vehicle emission control information labels may be found under the hood of the vehicle
Fig. Fig. 2: 1969-75 inline 6 cylinder engines
Fig. Fig. 3: 1969-75 V8 engines
Fig. Fig. 4: 1976 350 engines-Federal light duty
Fig. Fig. 5: 1977 350 and 400 engines-California G10, 20 and 30 with A/C (including heavy duty)
Fig. Fig. 6: 1977 350 and 400 engines-California G20 and 30 heavy duty without A/C
Fig. Fig. 7: 1977 350 engine-Federal G10 light duty
Fig. Fig. 8: 1978 350 engine-California light duty
Fig. Fig. 9: 1979 250 engine-Federal light duty
Fig. Fig. 10: 1979 250 engine-California light duty
Fig. Fig. 11: 1979 292 engine-California heavy duty
Fig. Fig. 12: 1979 305 engine-Federal light duty
Fig. Fig. 13: 1979 350 engine-Federal light duty
Fig. Fig. 14: 1979 350 engine-California light duty
Fig. Fig. 15: 1979 350 engine-High altitude light duty
Fig. Fig. 16: 1979 350 engine-California heavy duty
Fig. Fig. 17: 1979 350 engine-Federal heavy duty
Fig. Fig. 18: 1979 400 engine-Federal light duty
Fig. Fig. 19: 1979 400 engine-California light duty
Fig. Fig. 20: 1979 454 engine-Federal heavy duty
Fig. Fig. 21: 1979 454 engine-California heavy duty
Fig. Fig. 22: 1979 400 engine-Federal heavy duty
Fig. Fig. 23: 1979 454 engine-Federal light duty
Fig. Fig. 24: 1979 454 engine-California light duty
Fig. Fig. 25: 1980 250 engine-Federal with manual transmission
Fig. Fig. 26: 1980 250 engine-Federal with automatic transmission
Fig. Fig. 27: 1980 250 engine-California
Fig. Fig. 28: 1980 292 engine-Federal
Fig. Fig. 29: 1980 292 engine-California
Fig. Fig. 30: 1980 305 engine-Federal with automatic transmission
Fig. Fig. 31: 1980 305 engine-Federal with manual transmission
Fig. Fig. 32: 1980 350 engine-Federal
Fig. Fig. 33: 1980 350 engine-California
Fig. Fig. 34: 1980 350 engine-California with manual transmission
Fig. Fig. 35: 1980 350 engine-California with automatic transmission and inline diverter valve
Fig. Fig. 36: 1980 350 engine-California with automatic transmission and pump mounted diverter valve
Fig. Fig. 37: 1980 350 engine-Federal manual transmission with AIR
Fig. Fig. 38: 1980 350 engine-Federal manual transmission without AIR
Fig. Fig. 39: 1980 350 engine-Federal automatic transmission with AIR
Fig. Fig. 40: 1980 350 engine-Federal automatic transmission without AIR
Fig. Fig. 41: 1980 400 engine-Federal automatic transmission (heavy duty)
Fig. Fig. 42: 1980 400 engine-Federal automatic transmission
Fig. Fig. 43: 1980 400 engine-California manual transmission
Fig. Fig. 44: 1980 400 engine-California automatic transmission (heavy duty)
Fig. Fig. 45: 1980 454 engine-Federal heavy duty
Fig. Fig. 46: 1980 454 engine-Federal heavy duty
Fig. Fig. 47: 1981 250 engine-Federal and California with automatic transmission and auxiliary tank
Fig. Fig. 48: 1981 250 engine-Federal with automatic transmission
Fig. Fig. 49: 1981 250 engine-Federal with manual transmission
Fig. Fig. 50: 1981 250 engine-Federal with manual transmission and auxiliary tank
Fig. Fig. 51: 1981 292 engine-Federal and California with manual and automatic transmission
Fig. Fig. 52: 1981 250 engine-Federal with manual transmission and auxiliary tank
Fig. Fig. 53: 1981 250 engine-Federal with automatic transmission and auxiliary tank
Fig. Fig. 54: 1981 250 engine-Federal and California with manual transmission and auxiliary tank
Fig. Fig. 55: 1981 250 engine-Federal with manual transmission
Fig. Fig. 56: 1981 250 engine-Federal and California with manual transmission
Fig. Fig. 57: 1981 250 engine-Federal and California with automatic transmission
Fig. Fig. 58: 1981 292 engine-Federal and California with automatic and manual transmission
Fig. Fig. 59: 1981 305 engine-Federal with manual transmission
Fig. Fig. 60: 1981 305 engine-Federal with manual transmission
Fig. Fig. 61: 1981 305 engine-Federal with manual transmission
Fig. Fig. 62: 1981 305 engine-Federal with automatic transmission
Fig. Fig. 63: 1981 305 engine-Federal and California with automatic transmission
Fig. Fig. 64: 1981 305 engine-Federal and California with automatic transmission
Fig. Fig. 65: 1981 350 engine-Federal with manual transmission
Fig. Fig. 66: 1981 350 engine-Federal with manual and automatic transmission
Fig. Fig. 67: 1981 350 engine-Federal with automatic transmission
Fig. Fig. 68: 1981 350 engine-Federal with automatic transmission
Fig. Fig. 69: 1981 350 engine-Federal with manual and automatic transmission
Fig. Fig. 70: 1981 350 engine-Federal and California with manual and automatic transmission
Fig. Fig. 71: 1981 350 engine-Federal with manual transmission
Fig. Fig. 72: 1982 4.1L engine-Federal and high altitude with automatic transmission (G30 models)
Fig. Fig. 73: 1982 4.1L engine-California with manual transmission and auxiliary canister (G10 and 20 models)
Fig. Fig. 74: 1982 4.1L engine-Federal with manual transmission and auxiliary canister (G30 models)
Fig. Fig. 75: 1982 4.1L engine-Federal with manual transmission (G30 models)
Fig. Fig. 76: 1982 4.1L engine-California with automatic transmission (G10 and 20 models)
Fig. Fig. 77: 1982 4.1L engine-Federal with manual transmission (G10 and 20 models)
Fig. Fig. 78: 1982 4.1L engine-Federal automatic transmission (G10 and 20 models)
Fig. Fig. 79: 1982 4.1L engine-Federal with automatic transmission (G10 and 20 models)
Fig. Fig. 80: 1982 5.0L engine-Federal and high altitude with manual transmission (G10 and 20 models)
Fig. Fig. 81: 1982 5.0L engine-High altitude with automatic transmission (G10 and 20 models)
Fig. Fig. 82: 1982 5.0L engine-Automatic transmission G10 and 20 models
Fig. Fig. 83: 1982 5.7L engine-Federal and high altitude with manual transmission (G10 models)
Fig. Fig. 84: 1982 5.7L engine-Federal and high altitude with automatic transmission (G10 and 20 models)
Fig. Fig. 85: 1982 5.7L engine-Federal (G30 models)
Fig. Fig. 86: 1982 5.7L engine-California with automatic transmission (G20 and 30 models)
Fig. Fig. 87: 1983 4.1L engine-Federal with manual transmission (G10, 20 and 30 models)
Fig. Fig. 88: 1983 4.1L engine-Federal and high altitude with automatic transmission (G10, 20 and 30 models)
Fig. Fig. 89: 1983 4.1L engine-Federal and high altitude with manual transmission (G10, 20 and 30 models)
Fig. Fig. 90: 1983 4.1L engine-California with automatic transmission (G10, 20 and 30 models)
Fig. Fig. 91: 1983 4.1L engine-California with manual transmission (G10, 20 and 30 models)
Fig. Fig. 92: 1983 5.0L engine-Federal with manual transmission (G10 and 20 models)
Fig. Fig. 93: 1983 5.0L engine-Federal and high altitude with automatic transmission (G10 and 20 models)
Fig. Fig. 94: 1983 5.0L engine-Federal and high altitude with manual transmission (G10 and 20 models)
Fig. Fig. 95: 1983 5.0L engine-California with automatic transmission (G10 and 20 models)
Fig. Fig. 96: 1983 5.7L engine-Federal and high altitude with automatic transmission (G10 and 20 models)
Fig. Fig. 97: 1983 5.7L engine-California with automatic transmission (G10 and 20 models)
Fig. Fig. 98: 1983 5.7L engine-Federal
Fig. Fig. 99: 1983 5.7L engine-California
Fig. Fig. 100: 1983 5.7L engine-California with automatic transmission
Fig. Fig. 101: 1984 4.1L engine-Federal and high altitude with manual transmission (G10, 20 and 30 models)
Fig. Fig. 102: 1984 4.1L engine-Federal and high altitude with manual transmission (G10, 20 and 30 models)
Fig. Fig. 103: 1984 4.1L engine-Federal with automatic transmission (G10, 20 and 30 models)
Fig. Fig. 104: 1984 4.1L engine-Federal with automatic transmission (G10 and 30 models)
Fig. Fig. 105: 1984 4.1L engine-Federal and high altitude with automatic transmission (G10, 20 and 30 models)
Fig. Fig. 106: 1984 4.1L engine-Federal and high altitude with automatic transmission (G10, 20 and 30 models)
Fig. Fig. 107: 1984 4.1L engine-California with manual transmission (G10 and 20 models)
Fig. Fig. 108: 1984 4.1L engine-California with manual transmission (G10 and 20 models)
Fig. Fig. 109: 1984 4.1L engine-California with automatic transmission (G10 and 20 models)
Fig. Fig. 110: 1984 4.1L engine-California with automatic transmission (G10 and 20 models)
Fig. Fig. 111: 1984 5.0L engine-Federal with automatic transmission (G10 and 20 models)
Fig. Fig. 112: 1984 5.0L engine-High altitude with automatic transmission (G10 and 20 models)
Fig. Fig. 113: 1984 5.0L engine-High altitude with manual transmission (G10 and 20 models)
Fig. Fig. 114: 1984 5.0L engine-Federal with manual transmission (G10 and 20 models)
Fig. Fig. 115: 1984 5.7L engine-Federal with automatic transmission (G10, 20 and 30 models)
Fig. Fig. 116: 1984 5.7L engine-Federal with automatic transmission (G10, 20 and 30 models)
Fig. Fig. 117: 1984 5.0L and 5.7L engines-California with automatic transmission (G10, 20 and 30 models)
Fig. Fig. 118: 1984 5.7L engine-California with automatic transmission (G30 heavy duty models)
Fig. Fig. 119: 1984 5.7L engine-California with automatic transmission (G30 heavy duty models)
Fig. Fig. 120: 1985 4.3L engine-Federal and high altitude with automatic transmission (G10, 20 and 30 models)
Fig. Fig. 121: 1985 4.3L engine-Federal and high altitude with manual transmission (G10, 20 and 30 models)
Fig. Fig. 122: 1985 4.3L engine-California (G10 and 20 models)
Fig. Fig. 123: 1985 5.0L and 5.7L engines-Federal with automatic transmission (G10, 20 and 30 models)
Fig. Fig. 124: 1985 5.0L and 5.7L engines-High altitude with automatic transmission (G10, 20 and 30 models)
Fig. Fig. 125: 1985 5.0L engine-Federal and high altitude with manual transmission (G10 and 20 models)
Fig. Fig. 126: 1985 5.0L and 5.7L engines-California with automatic transmission (G10, 20 and 30 models)
Fig. Fig. 127: 1985 5.7L engine-California with manual transmission (G30 heavy duty models)
Fig. Fig. 128: 1985 5.7L engine-California with automatic transmission (G30 heavy duty models)
Fig. Fig. 129: 1985 5.7L engine-California with automatic transmission (G30 heavy duty models)
Fig. Fig. 130: 1986 4.3L engine-Federal and high altitude with automatic transmission (G10, 20 and 30 models)
Fig. Fig. 131: 1986 4.3L engine-Federal and high altitude with manual transmission (G10, 20 and 30 models)
Fig. Fig. 132: 1986 4.3L engine-California (G10 and 20 models)
Fig. Fig. 133: 1986 5.0L engine-Federal with automatic transmission (G10 and 20 models)
Fig. Fig. 134: 1986 5.0L and 5.7L engines-Federal and high altitude with automatic transmission (G10 and 20 models)
Fig. Fig. 135: 1986 5.0L engine-Federal and high altitude with manual transmission (G10 and 20 models)
Fig. Fig. 136: 1986 5.7L engine-Federal with automatic transmission (G10, 20 and 30 models)
Fig. Fig. 137: 1986 5.0L and 5.7L engines-California with automatic transmission (G10, 20 and 30 models)
Fig. Fig. 138: 1986 5.7L engine-Federal with manual transmission (G30 heavy duty models)
Fig. Fig. 139: 1986 5.7L engine-Federal with automatic transmission (G30 heavy duty models)
Fig. Fig. 140: 1986 5.7L engine-California with manual transmission (G30 heavy duty models)
Fig. Fig. 141: 1986 5.7L engine-California with automatic transmission G30 (heavy duty models)
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