trouble with firing

[gotbass7]

Recently, i made my second, more traditional, spudgun. the problem is i only got it to shoot once and it didnt shoot very good, but thats because the potato didnt have a tight enough seal.
well i tried to shoot it again and it didnt work at all. i tried several times, with a lot of fuel, barely any fuel, and everywhere inbetween. nothing. i checked the ignition. it worked. i think it might have something to do with the spark gap. i am using the ignitor from a long nosed lighter. but anyways the spark gap is very small. it has a spark, but a very tiny one. any help/suggestions would be greatly appreciated. im using axe.

[lukemc]

i dont care what you say if you have a spark than you dont have the right amount of fuel. an electrick spark is hotter than the surface of the sun so if there is a spark in that chamber with good fuel than is will work. how bigs your chamber i might be able to give you an estimate time for spraying

[Pete Zaria]

A spark gap of 1/4" or less should work fine for igniting atmospheric-pressure mixes.

The obvious potential problems I see are

A) fuel/air ratio/mixture is off (try less... or a different fuel)
B) fuel is not mixing with air well enough (chamber fan)
C) temperature/humidity/etc... conditions are creating problems.

Try less fuel. Try using propane from a torch (unmetered, starting with a little bit and working up) or engine starter/carb cleaner.

Try installing a chamber fan (80mm comp fans fit great in 4" pipe, 40mm fans will fit in 2"). A 9v battery and switch will run them. A 9v and two AA's in series make 12v and run it faster....

Make sure you're airing out the chamber between shots well enough, also.

Peace,
Pete Zaria.

[gotbass7]

ok. ill just let all the fuel in it now just kinda go out by keeping the cannons ends open. the chambers not much bigger then the barrel. i think its the smallest difference adapter for abs piping