Dual Capacity Pump Check

Dual Capacity Pump:

1. Bring the engine to normal operating temperature.
2. With the ignition off, actuate the throttle lever several times and observe the fuel stream. The stream should be strong and consistent.
3. Run the engine to refill the float bowl.
4. With the ignition on, actuate the throttle lever several times and observe the fuel stream. Less fuel should be coming from the pump because the solenoid is energized.
5. If the pump stream does not change and appears to be strong and consistent, fuel is not being bypassed by the pump circuit.
a. Disconnect the solenoid, fig. 1 coolant temperature switch connector and jump it to ground.
b. Repeat step 4. If less fuel comes from the pump, check cooling system operation and the coolant temperature switch for opens. If the pump stream remains the same, check wiring for opens or shorts.
c. Disconnect the dual capacity pump solenoid connector.
d. Remove the air horn assembly and gasket.
e. Remove the dual capacity solenoid from the float bowl and connect the solenoid connector.
f. With the ignition on and the coolant switch lead grounded, the solenoid should be energized and the solenoid plunger should extend. Replace the solenoid if it does not extend.
g. Check the pump valve and passages for dirt or obstructions.
h. Check pump system operation.
6. If the pump stream does not change and appears to be weak or irregular, fuel is leaking in the pump circuit.
a. Disconnect the dual capacity pump solenoid connector.
b. Remove the air horn assembly and the gasket.
c. Fill the float bowl and the pump well with clean fuel.
d. Seal the two pump discharge passages on the top surfaces of the float bowl with two fingers while pushing the pump assembly slowly into the pump well. The pump assembly should not travel to the bottom of the well. The only movement should be the compressing of the duration spring. If the pump assembly moves down in the well, the pump cup may be worn, hardened or damaged, the pump well may be worn or scored, the pump discharge plug may be leaking, the dual capacity pump solenoid plunger may be stuck, the pump valve may not be seating correctly, or the valve gasket may be leaking.
e. Connect the dual capacity pump solenoid connector.
f. Disconnect the dual pump solenoid coolant temperature switch connector and jump it to ground.
With the ignition on and the engine off, slowly move the pump assembly into the pump well until fuel is visible at the top of the passages.
h. Remove the pump assembly and continue to watch fuel in the passages. The fuel level should not go down. If the level begins to drop, the discharge ball may be missing or not seating correctly, damaged, or needs to be restaked. It may also indicate that the check ball in the pump valve is not seating properly.
i. Check dual capacity pump system operation.