If I have a gearpump, what kinds of signals will it give me that it's failing? Or will it just sizz up and stop? I'm pretty much shut down so I don't think I have killed it yet
Mine went bad, the oil burner wouldn't light sometimes and I had to push the reset button. Well it got worse where I would have to reset it every day, then finally it didn't light. I got lucky the plumbing place had one in stock, $90 or so a few years back. It wasn't a common oil burner, if yours is a Beckett or Carlin then you can buy parts anywhere and probably cheaper. I almost upgraded the whole burner but I was broke so I didn't.
An oil burner will do as you describe even with a good pump sometimes. The coupling that connects the motor to the pump is a hollow tube with a thick rubber neck. It simply pushes over a round shaft and powers the pump with the rubber's grip. If you run out of oil and prime it with the bleeder and don't use a hose, the oil can run down the back side of the pump and wet this coupling. An old tired one will do what yours did after a few drops sometimes.
If your burner exhibits this behavior, pull the motor and inspect the coupling first. if its old and tired or wet with oil. clean and dry it, shafts too. You can also wrap the shafts (motor and pump with duct or electrical tape) to snug up the fit. It won't last forever, but will easily get you a couple days. Its usually the coupling that goes, not the pump.