G&P M4 not firing after rebuild..

[aaron-hill09]

Evening all
I stripped down my Gearbox in my G&P enforcer today to give it a clean out and relube etc as it was bloody dirty!

Ive done a few V2 boxes in my time, but this problem is stumping me..

I refitted it, everything was moving nicely as it should and had good pressure out of the nozzle.. Rebuilt the gun to fire a few shots perfectly then it just stopped firing altogether...

After stripping it again, the tappet plate/nozzle just wasn't moving and there was a drop in pressure.. So I've stripped it again and am planning on rebuilding it tomorrow..

I'm just very confused as to how that's managed to do it? Why would it suddenly stop moving? Upon opening the box, it all looked fine realistically but the nozzle had come out from the tappet..

Other than taking it to someone who knows more, has anyone got any suggestions or ideas?

[sj_asc]

Re: G&P M4 not firing after rebuild..

Is it flat out dead? Do you hear anything at all when you pull the trigger? Did anything sound unusual before it stopped functioning?

If your getting nothing it's certainly an electrical issue, id check the motor connectors, they tend to work them selves loose after lots of takedowns.
Otherwise, the switch block, if you cleaned the contacts were you careful enough to keep them in shape? In many cases the moving trigger blade it's self only just reaches the two contacts, if you have had them apart from cleaning they may not both be meeting the blade it's self - no circuit.

Selector plate? I know most G&P's are straight through now and don't rely on the selector plate/have no electrical safe mode. But if yours does, it would be worth checking that the contacts are making a connection when the plate is in semi and full positions.

Switch block has flicked out of place, unlikely. You would notice it by a significantly lighter trigger pull.

Main wire it's self, has it shorted out on the GB casing it's self. Sometimes, particularly with silicone wire the GB guides can cut into the insulation You could do the insulation check without taking the box down, just take the motor out.

Motor height adjustment? (you would be able to hear it)

Other than this, poor shimming/no shims and other mechanical issues could be to blame, but unusual noise would be the tell tale sign. If there is a noise, then a description would help us diagnose.

[aaron-hill09]

It fires perfectly on semi and full auto.. As in, you can hear it all firing perfectly.. Just the air nozzle/tappet plate stops moving hence no BBs actually firing as there's not enough pressure!

So somehow it's slipping out of its position or something,

[aaron-hill09]

Update...

It now fires perfectly including the tappet plate and air nozzle working and moving as it should do... Both on semi and fully auto. I can feel the air coming out of the nozzle but it's still not firing when the magazine goes in (I'll get a couple of shots Out of it, then you an hear that the BBs are coming out of the mag etc. and it still fires and sounds supressed etc..


What I'm thinking is that the cylinder head may be pushed in a bit too far causing a gap between the hop and air nozzle so no pressure and BBs slipping through the hop unit...

Is that logical?

[sj_asc]

Re: G&P M4 not firing after rebuild..

The suppressed sound would be a result of a severe leak/seal issue. Did you airseal nozzle have an inner 0-ring?
Other possibilities - It could be many things
#Chamber position possibly affected by wiring (if it's front wired).
#Something obstructing the tappets rest position in the gearbox(would prevent the nozzle from returning as far as it should)
#Have you fitted anything else?

[webbjay]

Re: G&P M4 not firing after rebuild..

Not sure on the problem here but it sounds like sniperjesus has some good suggestions. I just wanted to point out that the cylinder head shouldn't be able to push further into the gearbox. There are pins in the gearbox shell which slot into the holes on the cylinder head. You will not be able to reassemble the gearbox if the cylinder head is not seated correctly.

[richardy]

Re: G&P M4 not firing after rebuild..

sounds like its worth taking apart and doing again to see if you can reseat what ever is out of place. Example i rebuilt my iphone 4 twice and still forgot the speaker cover. Im just saying theres a lot to it and sometimes rebuilding and reassemblings good enough to spot and fix some issues.

[aaron-hill09]

Good news is,

I rebuilt it all today, and it's firing a dream now.. Not 100% sure what it was still, but at least it's working nicely! One of life's mysteries that truly had me stumped!

Thanks all!