White smoke and a full UAT pretty much gets us down to the pump to engine installation.

Fuel lines on pump safety wired?

Jetcat fuel filter cap lubricated and on tight?

No festo's or instant style fittings in the feed line?

Using Jetcat ball valve for manual shutoff?

Good air purge from filter by hard shaking with the filter while  vertical, i.e., fuel in at bottom and out at top?  I usually do the purge at around 2v - 2.5v on the GSU.  How many flights since the last fuel system purge to the flameout?

Fuel line attaches straight into engine festo without side force on the line from inlets, structures, or loops?

Low probability thought:  I've seen pumps put air bubbles / fuel vapor bubbles in the line.  Probably due to a leaking seal on the motor shaft.  Tends to collect in the filter and pass to the engine at a bad time.</p>