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Re: Westerbeke 30B Deceleration Stumble/Stalling
Thank you. Can't say that I disagree with your reasoning. Here's the thing: this engine runs perfectly in all respects except for the rapid decel stumble.
I'm thinking there's some kind of overshoot that causes fuel starvation, wherein some kind of linkage or lever moves past where it should and gets stuck. The governor is the master of where the fuel injector rack is permitted to be. All throttle activity goes through it. If the governor "decides" it doesn't like some attempted throttle action, it won't happen. But, as you note, why something would malfunction only when the engine's warmed up a little is the mystery.
Basically, nothing's adjustable in the governor. It has flyweights that move a shaft in and out. The shaftend contacts a spring-loaded lever. This and other lever and linkage movements are controlled by several springs within the governor. Everything is splash lubricated by engine oil. Of course these are all calibrated springs. But, it's hard to imagine they would be affected only when the engine is warm, causing the rapid decl stumble.
I'm still open to the possibility that the problem lies elsewhere.