So, I have the 1973 Merc 500 that I have done a lot of work on; rebuilt carbs, replaced all wiring harness and spark plugs/wires, impeller, starter, fuel pump gaskets and lines, added a fuel/water filter/separator and a couple other things I think that don’t come to mind. If left sitting alone for a while I can prime the bulb and it gets fairly firm. Engine fires right up and can stay on idle for some time. I let it run for 30 minutes (purred like an angry kitten, but nothing I would not expect here) to see how it ran (on hose) then brought back to idle. Died right away. Let sit for a bit, could start but not stay running in idle position, but in minor throttle position, started and stayed running. I let sit for a bit and tried to primer bulb. Not firm at all. Primed fuel for a bit and the bulb never got firm again and I could not get engine to stay running longer than 2-3 seconds in idle. Any ideas?
