Had the same with my Volcano, Ialways seem to be to rich and if Idisconnect the line from top of fuel tank and blow through it, pushing nitro thru the exhuast which has decrease wait time. now my truck has the SH.18, my Earthquake on the other is set spot on and dead perfect as far as tuning, this is the SH .21, Icould run a entire tank through it, soon as it stopped couldnt get it to fire right back up. after closer inspections they flood out pretty easy, even if Iran it out of gas still had nitro in cyclinder. so removed glow plug and found this out. What Iwas told is run hot glow plugs, Iwas running mediums from start till this issue stopped. worked on my SH.21 no issues always lights right back up....now with the SH.18 I had to fiddle with the servo for the throttle but Ibought the slide carb for it.
http://www.rufaster.com/sh18slidecar...-te1809b2.aspx, with settings at 3.5 complete turns out LN, High 4.25 turns out, with HOTand HOT only Glow plugs. Never had the issue again with the volcano. Could be because I could never set the twist carbs....Hopefully helps ya some.