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1975-76 230 Models

  1. Disconnect Brown vacuum line at carburetor and Brown/Purple line at EGR valve. See Figure. Blow into Brown vacuum line and simultaneously increase engine speed to 3600 RPM. At idle speed, air should pass through vacuum line. Above 3600 RPM, air should not pass through vacuum line.
  2. If air can be blown through vacuum hose with engine speed above 3600 RPM, check the 3400-3600 RPM switch in RPM relay. If air cannot be blown through vacuum hose at idle, check vacuum hoses for damage and proper routing.
  3. Brown vacuum hose from carburetor should be attached to center connection of Brown switchover valve. Brown/Purple vacuum hose to EGR valve should be attached to outer connection of switchover valve. If correct, check switchover valve.
  4. Connect EGR valve to intake manifold vacuum. Disconnect Red vacuum line at carburetor and Brown/Purple vacuum line at EGR valve. Connect both vacuum lines. Engine should run rough or stall. If engine does not stall, check EGR valve.
  5. Increase engine speed to 2500 RPM and release throttle lever slowly. At the same time, observe vacuum control on carburetor. Vacuum control should extend above 2000 RPM and retract below 1800 RPM. If not, check vacuum control (on throttle lift).
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