Hard to start then will not start?

The owner replaced the fuel pump a few weeks later. The car became hard to start in mornings, progressively got worse now won't start. The fuel pump seems to be supplying fuel to fuel rail, when cranking, feel like fuel pressures is okay, starting fluid won't start it, not fuel related. Checking spark pulled plug wire put on a new plug grounded threaded part of plug, cranked engine had no spark, what do you check next? Crank sensor or mass air flow sensor? Double checked spark at plug #1 got a weak spark yellow.