Autococker Trouble Shooting Guide

This is a list of some common, and some not so common causes of problems with Autocockers.
If you are having a problem, find the heading that matches it, and check each possible cause.
The single most common cause of problems is timing.  Always check the timing first, then go on to check other causes. If you have a question about timing, read this Taking the Mystery Out of Timing an Autococker
Also, if you have just changed something on the gun, check that first. A new three way can cause the hammer lug to slip because of timing, a new ram can cause it not to cock because of a pump arm that is too short, etc. So, double check the last thing you changed before going farther than you need to.
 

Problems:
Barrel Leak
Three Way Leak
Ram Leak
Velocity is too Low
Velocity is too High
Velocity Fluctuations
Gun Won't Re-cock
Trigger Sticking Back
Chopping Paint

 

Problem: Barrel Leak

 

Hammer is resting on the valve stem When you gas up the gun, always make sure to cock it first. When the hammer is forward, it will push the valve slightly, and hold it open. This can cause either a massive barrel leak if the input pressure doesn't force the valve closed, or a brief spurt of air as the pressure closes the valve.
Inline regulator set too low, or the tank is low  By setting the line reg too low, there won’t be enough pressure to seal the valve. You will have to sweet spot the inline reg. A dead tank will give the same results.
Bad cup seal Your cup seal has seen the light, and either chipped, or just plain worn out. This can also be caused by using oils with solvents. Oil with solvents will soften the cup seal, and destroy it over time. Also, cup seals do wear out, so it may be plain old wear and tear. Replace the cup seal.  When you replace the cup seal, carefully inspect the valve body for damage on the sealing surface.
Bad valve face   The face of your valve is nicked, and won’t seal. To fix this use 800 or finer grit sand paper placed on glass to re-polish the valve face. Be careful to keep the valve face perfectly flat on the sand paper, or you will ruin the valve body.
Bad valve body o-ring The o-ring that seals the valve against the body has been damaged. You will need to replace the o-ring. Use a drop or two of oil on the valve body o-ring to make sure it doesn’t get damaged when you re-install the valve with the new o-ring.
Cup seal is dried out  Over time, the cup seal can become brittle. This is why it is important to put a few drops of oil in the ASA after every other case or so. Remove the barrel, put 5-6 drops of paintball gun oil in the ASA, and shoot the gun until you can hold a paper towel over the breach, shoot, and it stays clean.
Weak or short valve spring     A valve spring that is too weak won’t push the cup seal against the valve face hard enough to make a good seal. Also, if you try to use a Nelson style pump gun valve spring in a post 97 cocker, it will not be long enough to put any pressure on the cup seal. Use a stiffer valve spring, or a longer one.
Loose jam nut If the jam nut has become loose, the valve can shift and start to leak. Not only is the leak annoying, but a loose jam nut can destroy the body.  Check by removing the grip frame, and valve set screw.  Then use a pick to try and rotate the valve body.  If the valve body moves at all, the jam nut needs to be tighter.
Over tightened valve set screw.  If the vertical valve set screw is too tight, it can push the valve body, and cause a leak. This is most likely to happen with poorly machined bodies that have a slightly larger valve chamber than it should be.
mQ valve poppet seal is damaged If you have an mQ valve installed, a barrel leak can be caused by a damaged seal between the poppet and the valve body.  Carefully check the face seal, and the poppet body o-ring.  Damage to either of those will cause a barrel leak.

 

 

Problem: Three Way Leaks
LPR set too low  If the low pressure reg is set too low, there won’t be enough pressure to seal the three-way. This is common on three-ways with poorly fitting, or worn o-rings. 
Mis-timed The three way is set too close to the point where it will seal, and leaks. You need to re-time the gun.
LPR set too high On electronic cockers, the cocking noid will vent if the LPR is set too high.  Most times, this is a result of people trying to get guns to cycle as stupidly low CON and COFF settings.  So, check the settings on the LPR, and the frame.
Worn three-way o-ring  Over time, everything wears out. With proper oiling, three way o-rings should last a VERY long time, but if you run the gun dry, they don’t last long at all. A common problem with Bomb three ways, when people don’t lube the o-rings before putting them together. It can also be cause by a burr on the body of the three way, so take a look down the body while you have the shaft out. If you see anything sticking into the center passage, polish the bore, or replace the three-way.
Bent timing rod, or three way shaft  If your timing rod, or three way shaft is bent, it will push to one side, and create a leak on the other side of the three way. If the leak started right after you removed the grip frame, this may be the cause. Pull the three way shaft, and roll it on a piece of glass. If it wobbles at all, replace it. Do the same thing with the timing rod while you are at it.
Ram piston seal is damaged  When the ram is pressurized, the opposite side of the three way is a vent. If the piston seal on the ram shaft is letting air passed it, the air will vent out of the three way. To check the ram seal, pull the hose off the side of the three way that is leaking. Put it in a small cup of water, and watch for bubbles. If you see any, either rebuild the ram, or replace it.
Three way hose is ripped, or the hose barb is cracked If you hear a leak, and you can't find the exact location, spray the front end with some goggle cleaner. If you see bubbles at the very base of one of the barbs, that’s where the leak is. Try a new hose first, then check the barb for damage. If the barb is damaged, replace it. If it’s not damaged, but the leak is coming from the base of the barb, take it off, and put a tiny drop of Blue Loc-tite on the threads, and re-install it.
Solenoid gasket is damaged, or out of place With an E-Blade cocking solenoid, there is a gasket between the solenoid body, and the manifold. If that gasket is damaged, or out of position, it will cause a leak.

  
 

Problem: Ram Leaks
Hose barbs cracked or loose If you hear a leak, and you can't find the exact location, spray the front end with some goggle cleaner. If you see bubbles at the very base of one of the barbs, that’s where the leak is. Try a new hose first, then check the barb for damage. If the barb is damaged, replace it. If it’s not damaged, but the leak is coming from the base of the barb, take it off, and put a tiny drop of Blue Loc-tite on the threads, and re-install it.
Seal inside the back of the ram body is torn There is a small seal at the base of the ram. It seals the ram shaft and the body. If there is air coming out of the ram around the shaft, this o-ring has been damaged.
If you are not careful, and nick, or in any way damage the ram shaft where it passes this seal, it can become damaged. Rebuild ram if possible, and replace the ram shaft if it has been damaged, or replace the entire ram.  It is important to note that if you have damaged the ram shaft, even if you replace the seal, it will just fail again over time.
QEV leaks from the exhaust port This can be caused by a failed ram piston seal, or by a failed QEV seal.  An easy way to check is to gas up the gun, and hold the trigger back (set it to classic mode if you have an E-Blade).  If the leak switches from one QEV to the other, then it's a ram seal that has failed.  If the leak stays on the same QEV, take it apart, and clean the diaphragm, or replace it.  See the tech index for more information on how QEVs work.

 

 

Problem: Velocity is Too Low
IVG isn’t in far enough This means the hammer isn’t hitting the valve hard enough to open it for long, and that gives a low velocity. Make sure the velocity adjuster has not wiggled loose, and backed out.
Timing If the cocking point, and the firing point at too close together, the bolt will be coming back before the ball has left the barrel. This can cause massive inconsistency at the chrono, blow back, and a generally low velocity.  For more information on timing your gun, see the Tech index for the timing article.
Inline regulator is set too high  If the inline reg is set too high, the extra pressure in the valve will add resistance to the valve opening, and actually close the valve faster, and that lowers the velocity. Sweet spot the reg, and you should be OK.
Inline regulator is set too low Obviously, you need enough pressure to propell the ball at field speeds.  Follow the sweet spotting guide.
Valve spring is too strong This causes the valve to close faster and adds more resistance to opening the valve, and lowers the velocity. If you haven’t changed the valve spring, this isn’t the problem. The best choice is to use a lighter spring, but if you have no other choice, you can cut off a littel of the valve spring, and retest.  Just don't take too much off.  Over time, springs that have been cut can litterally unwind, and change their spring rate, so it's better to avoid cutting springs if you can.
Main spring is too weak The hammer isn't being driven forward with enough force to open the valve. If you haven’t changed the main spring, this isn’t the problem. Use a stiffer, or longer main spring to fix this.
Jam nut is loose The jam nut that holds the valve in the body became loose. This can prevent the hammer from going all the way forward, and striking the valve properly. This is a very serious problem. If the jam nut is left loose, it can damage the threads that hold the valve in place, and destroy the body. To check the jam nut, remove the grip frame, and the set screw for the valve that is under the frame. From there, you can use something soft, like a pencil, or tooth pick, and try to move the valve body from side to side. If it moves, you need to tighten the jam nut.
If you play with the gun in this condition, it will ruin the threads for the jam nut, and the body of th gun will be ruined.

 

 

 Problem: Velocity is Too High
Velocity adjustment is too high Sometimes, we forget the simple things.  If you are tweaking your velocirt with the inline, and can't get it under control, double check the velocity adjuster.
Main spring is too stiff  If you have been playing with the spring balance, try a softer main spring, and sweet spot the reg again.  Most time
Valve spring is too weak A overly soft valve spring used with an overly stiff main spring can cause uncontrollably high velocities. Change the valve spring, or try a lighter main spring andsweet spot the reg.

 

 

Problem: Velocity Fluctuations
Bad paint   Don’t think the $30 case of seconds you just picked up is going to shoot like tournament paint. It won’t. You get what you pay for, you are better off paying for good paint and getting the performance that goes with it.
Bad paint to barrel match  A poor paint to barrel match can do weird things with a cocker. If the paint is too small, the ball will roll part way down the barrel, and the first shot will be at a low velocity, while the next one is normal. Point the gun down, and give it a good shake. If the ball rolls out of the barrel, the paint is too small for that barrel.  Always point your gun slight up when you chrono, just to make sure you get an accurate reading.
If the paint is too big for the barrel, you can get blow back, and barrel breaks, erractic velocity,
Take the barrel off, and put a ball in the end. If you can blow the ball out of the barrel with a little puff of air, it’s fine. If it rolls, it’s too small, if it gets stuck, the paint is too big.
Inline regulator set too low Sweet Spot the reg if you see your velocity drop when you start shooting quickly. If the inline reg is set too low, it will cause your gun to be a gas hog, and can also destroy your consistency over the chrono.
Mis-timed  If the cocking point, and firing point of the trigger are too close, the back block will catch the hammer before it has opened the valve all the way. Slowly pull the trigger, and if the back block moves before the hammer falls, and comes to rest, then you need more room between the cocking and firing point. Re-time the gun.
Shoot down Shoot down is where the velocity drops when you start shooting quickly.  In some cases, it's a little drop off on a long, fast string of shots.  On more severe cases, it's a 50 fps drop if you shoot more than 5 bps.
If you have a mech cocker, some where in your air system, there is a problem. It can be anything from a kinked hose, to a gummed up regulator. Clean your regs, check the lines, and then sweet spot the inline reg.
For an electronic, check the timing, and LPR, as those two are more likely to be the problem, then check the air lines as above.
Velocity starts low, climbs, then levels off Your reg is letting too much pressure bleed into the valve chamber. This adds resistance to the valve opening (that lowers the velocity) then as the pressure is bled off, the velocity climbs. Rebuild your inline reg, and your problem should be fixed.
Velocity slowly drops as the gun is used  Check the o-ring on the IVG. If the o-ring is worn, the IVG can wiggle back as the gun is fired. Replace it with a normal tank o-ring if you do not have the correct one.  This can happen over the cource of a single game, or over the course of the day.  It all depends on how tight the adjuster is to the body, and how worn the o-ring is.
Loose jam nut: The jam nut that holds the valve in the body has come completely out of it's threads. This can prevent to hammer from going all the way forward, and striking the valve properly. This is a very serious problem.
If the jam nut is left loose, it can damage the threads that hold the valve in place, and destroy the body. To check the jam nut, remove the grip frame, and the set screw for the valve that is under the frame. From there, you can use something soft, like a pencil, or tooth pick, and try to move the valve body from side to side. If it moves, you need to tighten the jam nut.
If you play with the gun, it will ruin the threads for the jam nut, and the body will be ruined.


 

 

Problem: Gun Won't Recock
IVG is turned in too far This can limit how far back the hammer can travel, and cause the gun not to cock. If you can’t get the velocity you need from the main spring without cranking the IVG all the way in, sweet spot the reg, and try a slightly stiffer main spring.
Mis-timed  In this case it can be a couple of things. If the hammer lug is set too high, there won’t be enough surface to catch the sear, and the hammer lug will skip over the sear. If the three way is set to close to the cocking point, the sear won’t be far enough up to catch the sear as it passes. Retime the gun.
If you are running an electronic frame, take a close look at the CON or equvelent settings.
Sear spring is too weak, or out of place This can let the hammer lug skip over the sear no matter how far down the lug is turned. If you just had a trigger job done, try a stiffer sear spring, or a softer main spring. Also, make sure the sear spring is in the frame correctly.
Cocking rod too long, or is loose With the cocking rod set too long, the hammer won’t be pulled back far enough to catch the sear. If you can cock it manually, but it will not cock when pulling the trigger, check the low pressure regulator, and the cocking rod length.
LPR is set too low With the low pressure regulator set too low, the ram will not push the back block far enough back to catch the hammer lug on the sear. If you have an adjustable LP reg, check this first. If you are using a stock LP reg, and you haven’t changed the factory setting, then this shouldn’t be the cause.
Pump arm is too short If the pump arm doesn't push the back block far enough back to recock the gun. Remove the cocking rod, and pull on the back block. If the bolt completely clears the feed tube, and goes past it, then the pump arm is long enough.
Trigger stop screws If the trigger stop screws aren't holding their setting, they can move, and limit the trigger from completing the cycle.

        
 

Problem: Gun Won't Fire
Hammer lug is set too low  If the hammer lug is set too low, the sear will not drop far enough to release it when the trigger is pulled. Remove the frame, un-screw the hammer lug until it is almost flush with the hammer, and re-install the frame. Now set the lug to where it should be. For more information on timing, please read the Taking the Mystery Out of Timing an Autococker article.
Dead battery If you have an electro cocker, and the battery is low, there may not be enough power to drop the sear with each and every trigger pull. This can be compounded by the hammer lug being set too low.
Timing If the cocking point is before the firing point in the trigger pull, then the hammer never has a chance to open the valve.

 

 

Problem: Trigger Sticking Back
LPR set too high If the low pressure reg is set too high, it adds drag in the three way, and can cause the trigger to stick back. If you don’t have an adjustable LP reg, and haven’t messed with the stock reg, then this isn’t the problem.
If you have an adjustable LP reg, turn it all the way down, then slowly bring the pressure up until the gun cocks every time, then give it another 1/8th of a turn, and you should be all set.
If you can’t turn down the LP reg and still get the gun to cock (because the ram will have a weaker throw) oil the gun, and three way, and try again. If it still doesn’t work, your ram may need to be rebuilt, or a stiffer trigger return spring is needed.
Trigger return spring is too weak A common effect of poorly done trigger jobs. If you just had a trigger job done, or did one yourself, try a stiffer trigger return spring. If not, a stiffer spring will most likely fix your problem, but not fix the cause of the problem.
Damaged o-ring in the three way   If the o-rings on the three way shaft are damaged, they can cause extra drag in the three way. Pull the three way shaft out, and give the o-rings a good look. If they have any damage, replace them.
Trigger guide screws are set too tight   Sometimes, the guide screws on the bottom of the trigger frame can wiggle up, and cause a trigger to stick. You want at least a tiny amount of vertical play in the trigger. Pull it slowly back, and see if you can feel anything dragging on it.  If so, reset the vertical guide screws.
Trigger shoe is dragging on the trigger frame Trigger shoes can slip over time, or can be incorrectly. If you don’t pay attention when you put the trigger shoe on, it can catch the bottom of the trigger frame at the back of the pull, or the grip frame screw at the front of the pull. Check it just in case.
Timing rod is catching on the ASA  If the coupler on the timing rod is hitting the ASA, it can cause the trigger to stick. This is only a problem with sliding frames.
Trigger pivot pin is binding On some hinge frames, and on Eblades, the trigger pin is held in place by a set screw on the trigger.  That means that the trigger pin rotates with every trigger pull.  If the pin is rusted, or gummed up, that can cause extra drag that will prevent the trigger from returning as it should.

    
    

  Problem: Chopping Paint
Loader is not feeding fast enough Check the batteries in your loader, and if you don't have a motorized loader, get one.
Short stroking If you don’t pull the trigger completely back, and let it return completely forward, you can get all kinds of fun things happening with a cocker. Such as: Double feeds, skipped shots, pinched or chopped paint. If you are new to cockers, worry about pulling the trigger correctly, not quickly. Speed comes over time.
Mis-timed The cocking point and firing point are too close to the back of the pull. This means the three way isn’t opening all the way, and forcing the ram to the back of it’s travel. That catches the ball with the bolt, and can make a mess. Retime the gun correctly.
Pump armis too Short  If the back block is threaded too far onto the pump arm, the bolt won’t clear the feed tube, and that can butcher paint. There should be a small gap between the back block and the body when the gun is gassed up, and the bolt should completely clear the feed tube when the trigger is held back. The pump arm can twist over time, so you should check it before each game. Just a quick glance, if it’s not laying in the groove in the body, just flip it over until it sits correctly, or loc-tite the pump arm into the back block with Blue loc-tite, and don't worry about it.
Cocking sod is too short If the cocking rod is too short, it will limit how far back the back block can travel. That in turn limits the travel of the bolt, and you get chopped paint.
On top of making it more likely to chop paint, it also beats the hell out of the slot in the body, and will eventually cause major problems with the hammer moving freely.
Incorrect eye setting  If you own an e-blade, you have to set the eye sensitivity correctly to get the most out of the frame. Follow the directions in the manual to the letter.
If you have break beam eyes, check the ball in place settings, and make sure the eyes are clean.

   
 

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