Originally Posted by
Adverse Jaw
An unapproved but reliable remedy was to purge the fuel line by removing the boost engine igniter CB and perform a start cycle until a nice cloud of fuel vapour appeared from the jet pipe (usually requiring a helpful observer - or the startled comments of nearby a/c) A blowout cycle was then performed followed usually, by a good start.
I remember when I was training on GMC at Glasgow, T3s taxying for 24 (now 23) would start the booster as they passed the tower. First you would get clouds of vapour, then a gout of flame as it lit!!