on this pump there is port on the side whereby you can lock in the correct pump timing.
a special tool is required.
however i understand that an appropriate size bolt will work.
once the pump is "locked" and your crankshaft is at 15 degrees the engine is "timed".
i really beleive you have an airlock in this pump.
a similar situation almost drove me to the brink last year.
cranking the heck out of it will bleed the system but you run the risk of damaging your starter and your neighbours nerves