Fun to watch students try and start without the electric pump on. If engine is cold, it just takes a few extra cranks. But if you prime, things work fine. On a warm engine, electric pump isn't needed on an carb based low wing I've flown. Somehow, just about when you think students are actually checking what they do against a checklist, then they forget to use that electric pump. So I've found they just help a little, but are not totally necessary for starting.