Mine had similar issues at first. It would not quite start and if it did it was very brief and then stalled. I found if I turned it on and let it prime and then turned it off without starting. Then turned it back on again for a second prime. It always started that way. So, I raised the “Fuel Prime” setting and then it always started. I remember doubling the percentage at first and but brought it down some. You might want to try the “Double Prime” start to see if it helps before changing the setting.
Myself, I wouldn’t run without a gauge. My gauge detected a faulty regulator just testing the pump before the first start.