Bez F6

That sounds about how mine was when it was causing issues. It never left me stranded but a bit slower to start. Another thing that may help but won't fix it is to wait til all the dash warning lights have cycled after turning the ignition on but before hitting the start button. I'm not normally patient like that - just turn the key and go straight for the start. Relates back to the computers booting up properly, if they are up and running before the starter is engaged, they don't experience the voltage drop during the seemingly more critical boot-up phase.

Another possibility is that your battery is nearly stuffed or has a poor connection. I have a BF Typhoon, I had a couple of occasions years ago where weird things happened, including speedo & odo not working from startup, but if I stopped and restarted the car would come good again. Even though the battery was capable of starting the car, it's low voltage during start would cause the computers not to boot up properly. New battery and problem fixed. I don't recall this ever causing the boost gauge to stop working, but worth a thought. Easy enough to check the condition of your battery, and definitely time for a new one if it's becoming a bit slow to crank/start. Good luck with it.