While theoretically yes, they have enough energy to grab one single item it is merely NOT enough.
Because try the following:
- Put Burner Inserters on both sides along a belt and then let the belt fill with fuel.
- You'll notice that once the first Fuel Item comes along the belt, both Burner Inserters will try to grab the same item.
- One will succeed, the other will not.
- The one that didn't succeed gets stuck without fuel/energy to refill itself.
- You have to fill it manually.
And I'd say they should start with twice the amount, so they can get a second try if the first missed.
But there may be some people using 4 Burner Inserters around a single Requester Chest (for whatever reason), so I guess that's a tough decision.