Re: 1972 Merc. 80 HP fuel starvation??
What brand is your primer bulb? Aftermarket bulbs are notorious for having problems with the check valves, this causes fuel starvation.
Mercury had a TSB on fuel pump and bulb problems being caused by ethanol fuel. Merc came out with an new primer bulb with re-designed check valves that were less prone to deteriorating & sticking.
Next time you're out, instead of pumping the bulb have someone bang it on the side of the boat. If the check valves are sticking, this would jar them and perhaps keep the fuel flowing.
I take it from your description that after the first starvation incident, you'll pump the bulb then it'll run normally for quite some time?
If that's the case, the problem wouldn't be with the fuel pump. If the fuel pump had a problem, the carbs would run out of fuel very quickly and repeatedly at WOT. You'd have to sit there pumping the bulb quite a lot.
Now, if a float needle were sticking, pumping the bulb would blow it open and maybe it wouldn't stick for a while.
Did you install new floats and new needle/seat assy's in both carbs? If not, I would do so, they're not that expensive. Plus having newer, alcohol-resistant parts in there can't hurt.
Anyway, that's just a couple of ideas. You may want to pull the fuel pump apart just to make sure there isn't any 'trash' in the check valves, but other than that I'd look to the carbs or the fuel delivery.
HTH & G'luck..........ed
