Disclaimer: The following repair guide is provided for informational purposes. Not all these repairs have actually been tested here. iSoaker.com and its affiliates cannot and will not take any responsibility to any damages caused as a direct or indirect result of anything attempted. Use at your own risk/discretion.
Blasters belonging to the separate firing chamber tech category include the SS100, XP70, and XXP275. Water is put under pressure by pumping water from the reservoir into an air-tight firing chamber. Since the volume of the firing chamber is relatively small, it does not require as many pumps to reach maximum pressure. However, since the firing chamber has a smaller volume, the amount of water one can fire at once is more limited.
Pumping is difficult/impossibleIf the pump cannot be pushed or pulled (if applicable), its innards may have dried out and crusted. Try filling the reservoir with water and pulling/pushing harder on the pump. If it breaks, the blaster was useless anyhow.
If pumping is merely difficult, addition of some form of lubricant (i.e. Vaseline) to the pump shaft may help alleviate this problem.
Opting to open the weapon for a pumping problem usually does not help as the pump's shaft is typically sealed inside.
Pumping does not pressurize the firing chamberEnsure the reservoir has water.
Check the pump to see if it is still drawing water from the reservoir. If no water is beling moved when pumping, something may be blocking the water intake or the pump's seals may have worn down (in the latter case, repair the pump is usually not easily accomplished)
It is also possible that a tear has developed in the inner tubings between the reservoir and the firing chamber. If water is coming out of the housing of the blaster when pumping, an internal rupture is likely. In this case, one would need to open up the blaster and seek out the damaged part. Repair is often accomplished by either sealing the tear with hot glue and/or tape.
Blaster will not shootMake sure there is water in the reservoir and that the firing chamber is adequately pressurized. Try pulling the trigger harder.
Check the nozzle to make sure it is free of debris. If there is debris, attempt to clear the blockage by using a long needle/wire but be careful not the damage the nozzles or any of the blaster's inner-workings.
If using a blaster with multiple nozzle settings, ensure that the nozzle selector is properly aligned to the nozzle of choice and not in-between settings.
Blaster shoots mistOn some models, ensure the blaster is in an upright/horizontal position such that the output tubes are immersed in water.
Blaster continually shoots as soon as it is pressurizedOlder pressurized reservoir models control their water exiting the nozzle by a mechanism which pinches the soft, plastic tubing inside the blaster. At times, however, this mechanism loses its strength and is no longer able to pinch the tube properly, resulting in the continuous stream. The only remedy in this case is to open the blaster and look for the tube pinching device. It may need to be assisted in closing the tube when the trigger is not in use by attaching rubber bands to it. This, however, does not always work effectively and it may be in one's better interest to simply retire that blaster and purchase a newer, better built blaster.
Newer models have an enclosed plastic valve system which cannot be opened. However, sometimes the problem here is that the pistons on the valve that the trigger tugs on have become dirty. Removing dirt from the pistons and adding on a little lubricating oil can often help this problem immensely.
Blaster leaks around the firing chamberIn some older blasters, the O-rings which keep the firing chamber air-tight wear down. To repair this, one needs to open the blaster up, locate the worn down O-ring and replace it with a new one.