It probably has an internal switch.

I could be wrong in this case cause I cant see down the hole but there might be a float valve way down towards the bottom of the cavity.

You are correct. There's a diagram inside that space that presses a switch when the water gets high enough to provide adequate pressure.

Yes, it would be in/near the housing by the red arrow and is probably a diaphragm switch

Probably on the bottom of the pump

Diaphragm, but yes. Upvoted as the correct answer.

I tried to confirm it by filling up the well with water. Since the pump only turns on after it is submerged and then some, I sincerely doubt how it could be a float. So I agree, it seems like it must be a diaphragm.

Those diaphragm switches always screw up. Add a float to the circuit. They sell add on floats. Just make sure you get the right one. Some open on rise and some close on rise.

Yeah - I'm wondering since it's at least 15 years old if I should just replace the whole thing.

At 15 years old you should absolutely replace the whole thing.

15 is old for a pump. But I have seen older. The floats are cheap, a new pump is way more. But there are sweet pressure controls on the new ones. And variable flow rates too.

If you can afford it, go new. But a new float will get you through winter.

Looks like a 'Little Giant' brand. based on the picture there is a bunch of muck, so it is possible the opening that allows fluid to supply liquid pressure to the diaphragm. If it is plugged in, that could be the problem. Also, the discharge looks undersized too. this makes the pump work harder and has less performance (volume) . Replacement diaphrams can be bought if it torn. In the end replacing the pump is the recommended fix. I sold them for years.

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