auto sticking

[SuperSassy]

Workin on a km4 ris. Took apart my gearbox to grease up and upgrade. Been a long ordeal, but got everything together. Got the plugs sort of rigged up without heat shrink wrap to test it and everything worked. Pulled the wiring through the stock, wrapped, got it all set up, and now semi works fine, but when it's switched to auto it shoots on it's own with no trigger response. Any ideas?

[protogenxl]

You have a short that is bypassing the trigger contacts.
If you installed a mosfet the trigger wire is probably pinned by something and is shorting out when the the selector is moved to full auto.

Otherwise you have to go over the entire electrical path looking for damaged insulation and contact shorts. Basically remove a part then test the gun and repeat until find the cause of the problem.