I call it total bs that a kid that age could remember the blueprints/mechanics of a pump like that.
Also I hate that this is another totally pushover protagonist, and a "guy" with no interest to women, even though a guy at that age will surely have his hormones working better than they need to (if you can describe it like that).
And yes you can explain him being a bit insecure/pushover by his age, but that's the reason why I hate when authors decide to have these immature young persons as protagonist, who aren't even that interesting and are clearly mentally lacking.
Probably authors just wan't to have it the easy way, since younger people can be simpler in certain ways to write.