Dashpot System Check
- Connect tachometer to engine. Start engine and allow to reach normal operating temperature (cooling fan on). Disconnect vacuum hose from throttle control valve.
- Connect hand vacuum pump to throttle control valve and apply 8 in. Hg vacuum. Check that engine speed rises (within 1 minute) to 1500-2500 RPM on Accord and Prelude models or 1200-2200 RPM on Civic models.
- If speed was too low, widen the adjusting slot in the throttle control valve lever with a screwdriver. If speed was too high, narrow the slot with pliers. If speed cannot be adjusted, or diaphragm will not hold vacuum, replace the throttle control valve and retest. See Fig 2 .
- On Federal 1300 5-Speed Civic, go to Cranking Solenoid Valve Check. On Accord and all other Civics, if speed was okay, disconnect the vacuum pump and reconnect the hose. Raise the engine speed to 3500 RPM and maintain for 2 to 3 seconds.
- Release the throttle suddenly and watch how long the throttle opener arm takes to fully extend. Return time should be 1-4 seconds. If the engine speed returns to idle in 1-4 seconds with the arm fully extended, test is complete. On Accord and Civic models, go to Cranking Solenoid Valve Test.
- If return takes more than 4 seconds, check the throttle controller linkage for free movement, then replace the dashpot check valve and retest. If return takes less than 1 second, disconnect the hose from the throttle opener and connect a vacuum gauge to the disconnected hose. Start and run the engine at 4000 RPM.
- Vacuum should be at least 30 in. Hg. If so, replace dashpot check valve and retest. If vacuum is less than 30 in. Hg, check for vacuum at the carburetor port. If there is no vacuum, clean the carburetor port and retest. If vacuum is present, check the vacuum line for leaks, blockage or disconnected hoses and retest.