Accelerator Pump Valve

Accelerator Pump Valve (also called one-way valve or non-return valve) is a kind of umbrella valve, which is a critical component in the accelerator pump system of a carburetor, typically made of durable materials like silicone, liquid silicone, nitrile (NBR), HNBR, neoprene, EPDM, FKM, FVMQ (fluorosilicone) etc. Shaped like an umbrella or mushroom, Accelerator Pump Valve provides additional fuel injection during sudden acceleration to prevent a lean air-fuel mixture and engine hesitation.

Accelerator Pump Valve Structure

Mushroom Shaped Diameter: bigger than one-way valve holes

Hook Height: same to plastic & metal panel's height

Stem Diameter: same or maller than assembly holes

Outside Diaphragmatic Surface: EDM process or texture surface for dust proof

Inside Diaphragmatic Ring Edge Surface: Polish or high-polishing for sealing function

Accelerator Pump Valve Design Guide

Accelerator Pump Valve usually has undercut design structure, which should be made of material with high tensile elastic manuafctured by three-plate mold for avoiding damage when ejected valve from mold. But FPM & Fluorosilicone (FVMQ) material don't have so excellent high tensile property compared with Silicone Rubber material. When we design the valve, we usually make larger radius around the undercut for helping easier demoulding.

Accelerator Pump Valve Working Principle

        1. During Acceleration:

• The throttle is opened, and the accelerator pump piston/diaphragm pressurizes fuel.

• Fuel pressure lifts the umbrella valve’s sealing lip, allowing fuel to spray into the intake.

2. When Throttle is Released:

• Pressure drops, and the valve’s elasticity reseals it, preventing fuel backflow.

Accelerator Pump Valve Manufacturing Process

Accelerator Pump Valve Key Functions

1. Instant Fuel Enrichment During Acceleration

• Rapidly opens when the throttle is suddenly pressed, allowing a quick burst of fuel into the intake to prevent a lean condition (which could cause hesitation or stalling).

2. One-Way Fuel Flow Control

• Acts as a check valve, permitting fuel to flow only toward the engine’s intake and blocking reverse flow (prevents fuel backflow into the pump chamber).

3. Pressure Regulation

• Opens at a specific pressure threshold (e.g., 0.1–0.3 bar) to ensure fuel is injected only when needed, avoiding flooding or inefficient delivery.

4. Sealing & Leak Prevention

• Maintains a tight seal when closed, preventing:

• Fuel leaks at idle or deceleration.

• Air ingress that could disrupt the air-fuel mixture.

5. Responsive Throttle Transition Support

• Ensures smooth engine response during sudden throttle changes (e.g., overtaking or climbing hills) by synchronizing fuel delivery with demand.

Umbrella Valves in Stock

Why Choose Us?

1. Decades of experience about precision silicone rubber molding production.

2. We can offer high precises designs and sizes for silicone rubber valves to support your devices according to your 3D/2D drawings,samples, flowing parameters etc.

3. We have Dust-Free Silicone Rubber Compression Molding Plants and Dust-Free Dismantling Plants. 

4. According to customer demands, most of silicone medical parts should be produced and finished in clean room.Our dust-free plants can up to 100,000 stage.