Dashpot System Check
- Connect tachometer to engine. Run engine until normal operating temperature (cooling fan on) is reached. Disconnect vacuum hose from throttle control valve.
- Connect hand vacuum pump (except Civic models) to throttle control valve and apply 8 in. Hg vacuum. Check that engine speed rises (within one minute) to 1500-2500 RPM on Accord and Prelude models. On Civic models, disconnect vacuum hose No. 6 from throttle controller with engine idling. Engine speed should increase to 1400-2000 RPM.
Courtesy of AMERICAN HONDA MOTOR CO., INC.
- On Accord and Prelude models, if RPM was too low, widen adjusting slot in throttle control valve lever using screwdriver. See Fig 2
. If RPM was too high, narrow slot with pliers. On Civic models, loosen lock nut and turn adjusting nut. See Fig 3
.
- On all models, if speed cannot be adjusted, or diaphragm will not hold vacuum, replace throttle controller and retest.
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Courtesy of AMERICAN HONDA MOTOR CO., INC.
- On Accord and Prelude models, if RPM was okay, disconnect vacuum pump and reconnect hose. Raise engine speed to 3500 RPM and maintain for 2 to 3 seconds.
- Release throttle suddenly and note amount of time throttle opener arm takes to fully extend. Return time should be 1-4 seconds. If engine RPM returns to idle in 1-4 seconds with arm fully extended, system is okay.
- If return takes more than 4 seconds, check throttle controller linkage for free movement. If linkage is okay, replace dashpot check valve and retest. If return takes less than one second, disconnect hose from throttle opener and connect vacuum gauge to disconnected hose. Start and run engine at 4000 RPM.
- Vacuum should be at least 1.2 in. Hg. If so, replace dashpot check valve and retest. If vacuum is less than 1.2 in. Hg, check for vacuum at carburetor port. If there is no vacuum, clean carburetor port and retest. If vacuum is present, check vacuum line for leaks, blockage or disconnected hoses and retest.