Diagnosis
The chemical injector valve is clogged with dried detergent or the pickup tube is blocked.
How to Fix It
Remove the suction hose from the detergent bottle. Run clean water backwards through the hose into the injector to flush it. You can also remove the injector valve (on the pump) and soak it in hot water to dissolve residue. Use a wire to clear the small orifice.
If That Didn't Work
The injector valve's internal spring or check ball may be stuck permanently. The valve is a cheap replacement part. Get the exact model for the AR383 pump.
Heads Up
Always run clean water through the injector for 30 seconds after using detergent. Letting soap dry inside is the main cause of this clog.