To check the fuel pump operation, you can place the tank on top of a stepladder or something higher than the pump itself. This way, fuel will syphon into the pump instead of being sucked into it. These pumps can only lift fuel 30″ or so, anymore than that and the motor will starve.
Does the motor sneeze when it dies? If so, the top seal on the crank is probably worn and leaking. Does the bulb in the fuel line need squeezing again to prime the carb?
It was around ’69 OMC started thinking green and began doing something about the unburned oil going thru the motor. Where does the drain line from the front of the manifold go? It should terminate either on a nipple on one of the bipass covers or one of the bolts holding them on.
Also, is this a budget aftermarket fuel pump? If so, all the screws holding it together will need tightening to prevent any vacumm/fuel leaks.
The idle quality of motors from this area has always been questionable because of the green improvements. Opening the mixture needle slightly may help a bit, especially if there are any air leaks into it. Even though they don’t idle like a Cadillac, it should run like a scalded dog at WOT.
Here’s how I check for a leaking top seal.
https://youtube.com/shorts/cXt6fV6Z5rc?feature=share
