It’s obvious to a reader when a book isn't working, just like it’s obvious to a driver when a car breaks down. It’s not a matter of understanding what’s going on under the bonnet, the very fact of being stranded at the roadside is clue enough that all is not well. And it’s the same with a book.
I’m sure you know the feeling. The story begins to grate, to be irritating rather than intriguing. Or it simply falls flat. What should on the face of it be a dramatic scene – a fight at the top of a cliff perhaps – completely fails to thrill. Just like the driver, the reader doesn't need to know what’s going on under the bonnet, but for the writer (as the mechanic) it’s a different matter.
These kinds of nuts and bolts of writing were discussed in a series of short articles and on line exchanges at the very busy 48-hour launch of the Writers’ Toolkit a few years ago. Three extracts are linked here:
A story that should have the reader at the edge of their seat simply irritates the hell out of them – which part needs replacing?