I have since found that if the pump looses suction and runs dry , the easiest way to prime it is by disconnecting something on the discharge of the pump like an HSV, hose , gauge whatever ,then refill the reservoir and allow the pump to pump freely to atmosphere. After all the air is out of the system it will work as its supposed to.I have spent more than an hour trying to prime it and this is the only method that worked , in fact it primed itself in less than a minute when I "broke" the discharge , seems like the pump doesnt like to or cannot prime when its under pressure.

That makes sense. Can't get anything in, if you can't get anything out. Would a bypass help matters, probably not.

What about using a primer bulb from like an outboard boat motor?

TMS