i20 cranks but doesn’t fire. Eventually does fire when trying again later but slowly (video)
HYUNDAI i20 (PB, PBT)

Hyundai i20 intermittently hard to start. Happened three times in 7 months now. Last two times after cold snaps. Battery was replaced after second time this happened. Early in the morning, the engine will crank but no sign of ignition. Even a battery starter pack changes nothing. Once I’ve ruled out the battery (by charging it back to full) it then does slowly turn over, increasing in rate until its fast enough to fire (foot down on gas pedal). Once this has happened the air smells of fuel but from then on will start with no problem at all. 

This is a video of me finally being able to get it to ignite https://photos.app.goo.gl/8rQvxPfGMk2Zuu9e8

Multimeter shows alternator and battery are fine (measured after car has been off for hours). Battery wasn’t replaced the first time as it just started working on its own after we came back to the car hours later. 

Hopefully someone has experience of this as we can’t trust it for work any more!

Thanks!

Tim