My M4 sometimes decides not to fire

[JonMaximus]

Hey so I originally had a G&G M4 carbine but I've added a lot to it since then. New hop-up, bore, and now has a SIR rail system. It's all put together and fired fine.

But then today I tried to fire it again and it wouldn't. It half fired then nothing happens whenever I pull the trigger. I took out the motor and tested it and put it back it and now it fires fine again! This is the second time it's happened and it seems like I have to tighten a screw under the motor to make it work. But it took several attempts of taking the motor out and putting it back in for it to work this time. I haven't touched that part at all so I don't know why it would stop firing without cause.

Any idea why that happens?

[Jebus!]

It could be that you are putting the motor in the wrong position, that or you might have tightened the motor cover too much or too little.

[Rogue Reaper]

Or the spring is to heavy for the battery,

if the battery is a bit weak or the spring is to heavy or there is sticky gummy buildup on the piston rails.

All can be a factor. Are you blowing fuses?

[Rico]

I agree with Troy, sometimes the process of pulling the spring back will seize in mid draw, there are a few reasons for this. (listed in order of most likelihood for you)

1. Your battery is old, drained, or charged with the wrong voltage
2. You motor is old and not providing enough torque
3. You have too much load on the motor from the motor plate
4. You have wiring issues due poor maintenance and you are losing current
5. Your gears are not shimmed right
6. Your spring is too heavy for the motor / battery (m120 +)

[JonMaximus]

The motor and gear box are stock. If the case, how would I have drained the motor? I blew a fuse once a long time ago but haven't since then. As I said, it works now, but I'm concerned it'll stop firing again. If it does, will buying a new motor fix it?

[firemedic2296]

our CA did the same, we adjusted the motor height, it took several attempts to get it right.

[GacktC]

Check the red and black wires & motor pins that connected to the motor, sometimes they stripped due to always mounting the motor on and off.

[LiquidSnak]

Charge your battery properly with a smart charger and give it another go. If that seems to help, adjust your motor to the proper height and you are fine.