2. ACCELERATOR PUMP

Function

The function of the accelerator pump is to momentarily provide the additional quantity of fuel needed during acceleration, until the flow delivered from the main metering system increases. This is required whenever the throttle is suddenly opened.

The pump is a piston type pump, operated through the throttle linkage. It is used in stage I only. Located inside the float chamber, it is constantly surrounded by gasoline.

When the pump lever is actuated, the pump piston forces fuel through channels and out through the calibrated injection pipe into the carburetor throat.

Problem

Examine pump plunger for damage and sticking. A faulty accelerator pump will cause:

1. Hesitation on acceleration

2. Stalling

3. Fuel consumption

Test: Pump lever should have tension‹if not, pump is binding in bore

Adjustment

To check the accelerator pump for proper function the top cover and pre-atomizer in the primary stage must be removed.

1. Start of Injection Immediately on opening the throttle, a powerful jet of fu' should emerge. (See Fig. 1)

2. Injection Amount Using a graduated container‹part no. 111-589-17-21-00, pump for one full stroke. The amount should be 0.7-1.0 cc. (See Fig. 2, 2A.)

Inspect accelerator pump checkballs, inlet and outlet. (See Fig. 2B)

3. Adjust the injection amount by bending the internal lever. (See Fig. 3)

4. Direction of injection. Pre-1972 and 1972 (See Fig 4)