P90 does not shoot in semi

[RainyEyes]

The p90 does NOT shoot in semi. It will not shoot at all.

King Arms P90. Quick spring change gearbox.

Fires fine on automatic inside and outside the mechbox.

I don't believe it's a cutoff lever issue since it won't shoot in semi at all, meaning it will not fire. Is there any fix to this?

Edit: I put some tape on the trigger bar, now it will fire sometimes, but only on full auto. I have to pull the trigger all the way back for this to happen, and it's an on-off chance that something connects.

[CyanideApple]

Switch to full auto then back again, my KA P90 is finicky like that too, or just stick with full auto and use the 2 stage trigger pull, unless you mean that it doesn't work regardless.

[Short Round]

Did you take your gearbox out?

[RainyEyes]

Originally Posted by Short Round

Did you take your gearbox out?

Unfortunately, yes. I had to reshim it because of reasons. e.g. the gearbox age was unknown. When I opened up inside, it was factory stock shimmed, caked on crusty cracked grease and black sludge EVERYWHERE.

Fortunately I figured out the problem. The internal contacts were not engaging the trigger contacts. It now shoots semi-auto.

[pestobanana]

Any time a gun with a two stage trigger only goes full auto, first thing to check is the trigger contacts. Glad you figured it out yourself.

[Short Round]

Originally Posted by RainyEyes

Unfortunately, yes. I had to reshim it because of reasons. e.g. the gearbox age was unknown. When I opened up inside, it was factory stock shimmed, caked on crusty cracked grease and black sludge EVERYWHERE.

Fortunately I figured out the problem. The internal contacts were not engaging the trigger contacts. It now shoots semi-auto.

This is good

[Zfurlong]

I am having a similar problem with my p90, but mine only shoots semi, what are some common issues that cause this?

[lurkingknight]

take thegear box out and see if the trigger block pulls all the way back to make contact with the full auto trigger contacts. If it doesn't, bend out the tabs a bit.

[RainyEyes]

Originally Posted by Zfurlong

I am having a similar problem with my p90, but mine only shoots semi, what are some common issues that cause this?

If your p90 only shoots semi, you need to take the gearbox out of the shell and inspect the contacts on the EXTERIOR trigger contacts.

With the battery unplugged, pull the outside contacts so that they touch. Make sure both tabs are engaged to the contacts, because both slabs of metal need to touch to complete the circuit. If not, you may need to adjust the distance of the tabs with solder or some bending forward.

If both are touching, test the automatic fire with the battery plugged in. Does it shoot? If so, move to the next step:

If it fires automatic with the battery in, your next step to troubleshoot is to inspect the trigger bar in the body of the gun. GRADUALLY apply tape to the trigger bar so that it is sufficient to apply the necessary movement of the trigger bar to its contact so that it engages the metal tabs.

If it does NOT shoot (fires once and stops completely) you must check the wiring to ensure that the wires are correctly connected and make sufficient contact.

Cheers.

[jordan7831]

Actually, for P90 semi auto problems there is another cause.

1. The trigger trolly could be broken. When the trigger is pulled back, the trigger trolly moves back to a point where it completes the circuit. After a certain point, a spring kicks it back to the resting position, breaking the circuit.

What can happen is that the very small tabs on the trolly can break, causing the trolly go off its tracks and becoming stuck in full auto. In other words, it cannot spring back because it gets wedged into place.

2. Another potential problem is from the trigger linkage. Because the P90 is a bullpup. Like all bullpups (Aug, Tavor) there is a linkage (usually a piece of wire) that connects the trigger on the grip to the gearbox.

For the P90, the trigger bar can become bent, or the gearbox retaining plate could be slightly loose allowing the gearbox to move back slightly. It doesnt take much, 1mm will do it. This problem exist on both the Aug and P90 because of their 2 stage triggers. Also the fact that they are held in place by a plate plays a factor.

You can tell if this is the problem by pushing the gearbox forward and testing semi. If semi starts working, then the gearbox is not sitting far enough froward. If the gearbox is as far forward as possible, you may try wrapping some tape around the trigger linkage to shim it up.

http://www.airsoftgiforum.com/viewtopic.php?f=12&t=7414


Jordan

[RainyEyes]

Originally Posted by jordan7831

Actually, for P90 semi auto problems there is another cause.

1. The trigger trolly could be broken. When the trigger is pulled back, the trigger trolly moves back to a point where it completes the circuit. After a certain point, a spring kicks it back to the resting position, breaking the circuit.

What can happen is that the very small tabs on the trolly can break, causing the trolly go off its tracks and becoming stuck in full auto. In other words, it cannot spring back because it gets wedged into place.

2. Another potential problem is from the trigger linkage. Because the P90 is a bullpup. Like all bullpups (Aug, Tavor) there is a linkage (usually a piece of wire) that connects the trigger on the grip to the gearbox.

For the P90, the trigger bar can become bent, or the gearbox retaining plate could be slightly loose allowing the gearbox to move back slightly. It doesnt take much, 1mm will do it. This problem exist on both the Aug and P90 because of their 2 stage triggers. Also the fact that they are held in place by a plate plays a factor.

You can tell if this is the problem by pushing the gearbox forward and testing semi. If semi starts working, then the gearbox is not sitting far enough froward. If the gearbox is as far forward as possible, you may try wrapping some tape around the trigger linkage to shim it up.

http://www.airsoftgiforum.com/viewtopic.php?f=12&t=7414


Jordan

No it was the internal trigger set. I know because i made it touch (like a sandwich) and it didn't fire.