As stated on DH2 page 224, fixing a Weapon Malfunction is a Full Action that requires a Challenging Ballistic Test.

SOLID PROJECTILE WEAPON MALFUNCTION
Cylinder weapons can then be fired. Magazines are locked-up, ruined & must be replaced – but the ammunition within it is still usable.

FLAMER MALFUNCTION
Only the first damage roll made from a single flamer shot determines if there is a weapon malfunction (e.g. if there’s multiple targets hit from a single flamer shot, the damage roll to the 2nd target cannot cause a malfunction).

If damage roll comes up a 9 then there is no damage as the Flamer malfunctioned – roll 1d10:
1-2: Ignitor flame went out on weapon; target was sprayed with non-burning promethium. Remaining fuel (ammo) still good but roll BS each subsequent turn to re-light ignitor flame.
3-8: Clogged nozzle causes pressure to build blowing safety valve on fuel tank which dumps all remaining fuel on ground, preventing possible catastrophic result. Roll BS Test to unclog nozzle & then need to reload tank with fuel.
9-10: Flame spreads to fuel tank, which erupts in flames. Roll Ordinary Agility Test (not Dodge Test) to quickly toss weapon/tank away or suffer weapon’s attack damage (to Body). If at least 1 point of damage is taken from attack then roll another AG Test to not catch on fire.