spud gun

[fla_countryboy]

I just made my first propane powerd spud gun but iam having a problem with it igniting the propane. iam using a BBQ ignition switch its creating spark in the chamber but no combustion. I dont have a fan installed in it but I though it would still combust can anybody please help me? thanks

[fla_countryboy]

pppppppppppppppppppppppllllllllllllllllllllllllllleeeeeeeeeeeeaaaaasssssseeeeeeee help!

[jrrdw]

When you fill the chamber with fuel does it build any pressure at all? Here's why i ask -- it is allways harder to genarate a spark under pressure then when it's in a equal atsmophere, (not under any compression). Or maby to much fuel, not enough???

[Insomniac]

How much fuel are you using??? How big is the gun??? Are you using a meter pipe or the older 'spray'n'pray meathod??

Try putting in 1 seconds worth of propane, click the ignitor, then if it doesn't work COMPLETELY vent the chamber and try again with 2 seconds. Then 3, 4, 5 etc

The most likely problem is that you are putting way too much fuel in.

[squeaks]

#1 don't double post, edit your post.

#2 don't whine about your problems, people will be less likely to help.

#3 did you do the stoichiometry for the size of your meter pipe compared to your chamber to get the correct pressure when injecting propane? If not are you just holding the propane bottle in the chamber(I'm assuming you're smart enough to turn the propane on)? A couple seconds of propane should do. Start with 1 second and move your way up until you start losing power.