Bronco L6-300 4.9L VIN Y 1-bbl (1983)
Accelerator Pump: Testing and Inspection
1.
Allow engine coolant to stabilize to ambient temperature.
2.
Start engine and immediately check for vacuum at the temperature compensated accelerator pump valve.
3.
When the engine is cold, no vacuum should be present.
4.
Allow engine temperature to stabilize and check to ensure that a vacuum greater than 10 inches Hg is present at the temperature compensated
accelerator pump valve.
5.
If the vacuum signal to the valve is incorrect in either hot or cold mode, check vacuum hoses, connections and vacuum control valve. After a
vacuum is verified, shut-off engine and connect a six inch section of clear tubing (5/32 inch inside diameter) between the temperature compensated
accelerator pump valve. If no fuel is flowing, remove clear tubing and install vacuum hose to the temperature compensated accelerator pump
valve. Turn ignition switch to off position.
6.
With ignition switch in off position, remove carburetor air horn and air horn gasket. If the engine is warm, relieve pressure on fuel inlet needle by
carefully depressing fuel bowl float.
7.
Carefully remove float and needle assembly.
8.
Remove enough fuel from the float bowl so that the temperature compensated accelerator pump bleed hole is just at or above bowl level.
9.
Remove vacuum hose from valve and actuate accelerator pedal at a moderate or fast rate, and observe fuel discharge out of the temperature
compensated accelerator pump bypass bleed. No fuel discharge should be observed from the bypass bleed. If fuel does discharge, replace valve.
10.
Using a hand operated vacuum pump, apply a vacuum greater than 10 inches Hg to the temperature compensated accelerator pump valve. Actuate
accelerator with a very quick action from idle to wide open throttle, fuel should discharge from the bypass bleed. If fuel is not discharged, replace
temperature compensated accelerator pump valve. Install float and needle assembly, air horn and a new air horn gasket. Tighten attaching screws
securely.
