Poltergeist in my TM M4A1 R.I.S

[FNG]

I beleive that my M4 is demon posessed. Or...I'm an idiot...could be both.

First a little history of the gun then on to the whole demon/idiot thing.

I bought the gun used but nearly new in stock form. Afterward I upgraded the spring and bushings, reshimmed it and put in a 20A fuse. It was an unknown spring but it brought the FPS up to 395-400. It was gamed with a few times and performed flawlessly....then it didn't. I had already decided to switch out the spring before the mechbox went kablooie anyway so now was as good a time as any. Little did I know that the demon (or my stupidity) had already taken hold.

This what the gun does:

With a fresh battery (mini 8.4 or 9.6) it will fire about 40 rounds then start to feel sluggish, the battery heats up then it stops firing. The spring will be near fully compressed but it will not crank past that last tooth to release the piston. You can hear and feel the motor struggling to turn but it doesn't.

This is what I did:

I openned the mechbox and tossed that spring. Cleaned all the gears and inspected them, no wear was present on any of them, the motor or piston. I reshimmed it again thinking I screwed it up the first time. I then installed a PDI 150 spring, regreased and reassembled the gun.

The poltergeist laughed and it did exactly the same thing as before.

So I scratched my head, got that stupid look on my face, had a beer and decided to try again in the morning.

After taking it apart again, visually inpecting all the wiring and cleaning all the contact points. I reassembled the gun now with a Gaurder SP100 spring.

Again the demon laughed. It did exactly the same thing. Fires 40-70 rounds, starts to become sluggish, battery heats up and it stops firing with the spring almost completely compressed.

Does anyone have any insight as to what I've overlooked, or done incorrectly?

[Deftonius]

Did you check your fuses? You pretty much covered everything, but it definately sounds like a wiring problem to me. You could messed up a fuse and not known it? There's no other real reason the battery should get that hot that fast.

[vondnik]

ditch the fuse and the pdi150

check you wireing harness for any snags on any of the wires as you may have a short somewhere usualy the red wire touching the mechbox somewhere.. check you selector plate to make sure all contacks are in decent shape, also clean out and check your trigger assembly. ALso i'm sure you tried different batteries right?

[Death March]

How old is the Motor? could be worn out and I did't see you say that it was blowing fuses,but you say the battery is getting hot! That would tell me it's taking alot of Amps trying to turn over that spring.I had the same type of things happen after installing a M120 spring and it was the old motor did't have enough torque and the battery was a mini.I had to use a 9.6 1700mAh (crane stock).You might want to check the state your battery is in as well,you might have a dead cell and I'v had that happen too.Hope this gives you some ideas !

[SEALs]

is your gearbox timing's well set? A wrong timing could exessive strenght to pull the spring pass the last tooth of the piston. Already happened to me.

[mcguyver]

HaHa, timing. No such thing!!

Do as Vondnik says, but keep the fuse. It's there to protect your motor mainly. Heating of the battery is due to excessive current discharge. If this only happens when you pull the trigger (battery won't heat up if it's connected to the gun and just sitting there), then your problem lies after the switch.

Sometimes guys will nick the red wire right at the trigger and not realize it. Good place to start looking.