How do I know if my accelerator pump diaphragm is bad?
Signs that your accelerator pump may need to be replaced include:
- Car does not accelerate smoothly when gas pedal is pressed hard (note: a bad accelerator pump does not affect slow acceleration, only fast acceleration)
- Engine stalls or stutters during hard acceleration.
- Exhaust smoke.
What does a bad accelerator pump do?
Rough acceleration If there is any problem with the pump, then there will be a problem in the fuel mixture during acceleration. Usually, a faulty accelerator pump will result in a momentary lean condition, which can result in rough or sluggish acceleration, and even misfires.
Where is the accelerator pump on a carburetor?
By manipulating the cam, the quantity of fuel dispensed by the pump can be adjusted from a small spritz to a large squirt. The accelerator pump is located on the bottom of the fuel bowl of the carburetor. On a typical barrel system, there will be a single pump.
Do you need a secondary accelerator pump on a Holley carburetor?
Mechanical secondary Holley carbs (right) do require a secondary accelerator pump circuit since the secondaries can open even at very low engine speeds. All 4150 and 4160 style Holley carburetors use the standard 30cc pump reservoir.
What causes off idle hesitation on a Holley carburetor?
The most common cause of an annoying off-idle hesitation on Holley carbs is when the primary bowl has been removed and re-installed. It is very easy to replace the fuel bowl in a slightly different position that can create additional clearance between the accelerator pump cam linkage and the pump.
What kind of parts does Holley make?
Holley’s products include carburetors, fuel pumps, fuel injection, intake manifolds, and much more. From start to finish, Holley has the parts to make your dream a reality.
What is the size of the accelerator pump on a carb?
The stock primary accelerator pump nozzle size on this carburetor is a 0.031-inch while the secondary side is slightly smaller at 0.028-inch. A simple cure might be to increase the size of the primary accelerator pump to perhaps 0.035-inch and evaluate the change in engine performance.