mrs purple was grizzling at non start of her sele and a hard brake pedal, all I did was adjust the metal lever that operated athe brake switch so it came on a little sooner.
Turns out it was all my fault. I was replacing a brake light bulb, in checking is function I repeatedly pressed the brake pedal destroying the servo vacuum making the pedal hard. Mrs P gets in and with her dodgy back could not get enough pressure on the pedal to get the brake light on, and a silly will not start without the brake being on, and the trigger for this is the brake light switch. Simply bending the metal a couple of mm made the difference.
That said, if your pump is not running there is another issue to contend with as well, however it is worth checking that the brake lights are on when it is refusing to start.