M4 auto firing

[RaisinBran]

So I plugged in my lipo into my new WE M4 fired 2-3 shots in semi to chrono it and it just started to shoot by itself on full auto. It only stopped when I unplugged the battery.

I tried plugging it back in and as soon as I did it started shooting by itself again.

I switched out the motors, thinking it as a motor problem and the gun is perfectly fine now, is the original motor fried now?

[HKGhost]

You have a short circuit somewhere. If changing the motor fixed the issue, then the motor is causing a short. You need to check the motor and see where it's causing the two leads to making a circuit. Could be the bell housing if it's metal (Systema motors are prone to this).

[daishi]

The stock motor on WE aeg models can be hit and miss depending on the version and a host of other things. As ghost said, just check the housing...you could also compare the motors and see if you notice anything.

Off topic:
Heh that must have been a fun time having your loaded m4 suddenly go full auto while you fumble to get the battery out. Guy with a highcap mp5 at a game had this happen....BB's EVERYWHERE. Im pretty sure he got some kills tho

[RaisinBran]

To be honest it scared the shit out of me... Another odd thing that I forgot to mention is I don't think it is a stock WE motor as the motor was a Classic Army High Torque motor, odd right?

But yeah I hope it's just the motor, don't want to be plugging my battery in a game and have it go full auto.

[XZIVR]

I'm not entirely awake at the moment but I'm having a hard time imagining how the motor could possibly cause this. My money would be on the trigger contacts getting stuck and while you were changing the motor out, you managed to bump the gun enough that the contacts came back apart. Check the trigger IMO..

[R.I.T.Z]

trigger contacts could be melted together. or some wires may be stripped.

check your wires, and if they're not stipped, you will have to check your gear box

had this happen in my BCR project a few times.
wires where stripped in the stock and caught fire.
trigger contacts melted and auto fired

[j3ttamaster]

^
^
+1

[RaisinBran]

Yeah I'm pretty sure it's the motor though, checked everything, gun works flawlessly with the new motor, all the wires are perfectly fine no stripped wires, contacts are fine too.

Thanks for the help.

[XZIVR]

I'm having issues understanding the physics of how a bad motor could just start firing all on its own. How is it getting power if the trigger is functioning correctly? Since it's always grounded to the battery, even if something happened to cause the gb housing to go live when the battery was plugged in, the result would be a dead short. I think I'm going to have to stand by my original comment..

[MaciekA]

Originally Posted by XZIVR

I'm having issues understanding the physics of how a bad motor could just start firing all on its own. How is it getting power if the trigger is functioning correctly? Since it's always grounded to the battery, even if something happened to cause the gb housing to go live when the battery was plugged in, the result would be a dead short. I think I'm going to have to stand by my original comment..

You can imagine it happening with a metal end bell like with the troublesome Systema motors that sometimes have this problem, because then there is a chance the circuit can be completed via some other route than the actual trigger, instead running the gearbox somehow. I've seen shorts where the current would have had to run through the gearbox shell itself in order to complete the circuit, with the gun firing even though the trigger contacts aren't even touching. It's pretty crazy.

Having said that, I agree with your original analysis. The trigger contacts could be sticky upon firing, and then getting rattled apart by the "bad" motor's vibration (or something of that nature).

Thus if this were one of my own guns, I wouldn't completely trust that the short is gone yet. A careful inspection should be done. Shorts are no joke ... an injury could result.