1969 Mercury 7.5 HP repairs

I have a 1969 Mercury 7.5 HP that runs strong, but has a couple problems. It doesn't spit very much water from the telltale, and I have already replaced the impeller and checked the telltale line with a piece of wire. It doesn't overheat, and I've been using it daily for about a month like this. I recently got a second outboard, so can take this one apart.

Also, it runs for a few minutes then dies unless I keep the primer bulb pumped up, in which case it runs fine all the time.

I'd like to fix these issues, as well as do any other maintenance items that would be worthwhile. This is a motor run exclusively in saltwater, on a 12' Sears semi v. Unfortunately there is no fresh water source near the dock, so it only gets a freshwater flush a couple times each year, but most everyone around here only flushes once or twice a year.

Also, it runs for a few minutes then dies unless I keep the primer bulb pumped up, in which case it runs fine all the time.

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Fuel pump may be weak.

I just received a 7.5 Merc from a customer that he wants me to go through.

I had a 66 model 3.9 merc that had the same 2 issues. I replaced the impeller and rebuilt the fuel pump. The water flowed slightly better but still not quite what I thought it should be. It continued to die unless I kept the bulb pumped. After quite a bit of testing, I discovered the O-ring inside the female connecter (that attaches the line to the engine) had a small nick in it, allowing it to suck just enough air to prevent the pump from being able to do it's job. I replaced the O-ring and never had another fuel problem. I continued to run the motor with what I considered weak water flow up until I sold the motor this spring.