Genrac power washer chemical injector not working

I suspect you are asking about the chemical injector.
there is a brass barbed fitting that you should slide the chemical hose over, not the black nipple

I am assuming you mean the chemical resovoir tank? If water is running out of it then water is coming back up your chemical injector. This usually means at some point the ball and spring in your injector got stuck...typically people take them apart at the nipple to ry and fix it. not realizing there is a small ball and spring in that nipple. This is actually a ball valve to prevent water from coming out of the chemical injector nipple. Replace the ball and spring if needed as well as the oring seat in the nipple. This will stop your tank from filling up. Good luck

This unit has a Faip pump on the unit, no water should come out the chemical injector. The chemical injector can be closed off with no problem by installing a plug where the chemical injector hose bard is currently located.
You can also replace the chemical injector, here is a link to view the part.
www.allpartsinc.com/ProductDesc.aspx?code=KTRI91351

Soap injectors are easily clogged or will not work because of design (air leaks will prevent chem from entering if chemical has to be drawn uphill) . They work with siphon action and will only work with very little pressure at the tip but good volume. If your siphon valve has the ball in place, however is missing the fine spring that holds the ball against seat (fine spring holds ball aginst intake fitting), the soap will not be sucked into stream. If ball and spring are in place, try elevating the soap container higher than the opening of the port (gravity feed may help to feed soap into system) . May be better to use an aftermarket downstream injector valve sold on ebay or many outlets. Cost about $20 but work better and are adjustable to save on soap. Search ebay for "Chemical Injector For Pressure Washers" or google "Pressure Washer Downstream Chemical Injectors" Various prices but lower price units work better than factory. Good luck

The first problem might be that you are trying to use the wrong nozzle, see this link to read more about what nozzle to use for detergents

If you still have an issue the problem is going to be in the chemical valve on the pump, there are two different styles they have on this type of machine, look at the links below on directions on how to repair your chemical valve.

Chemical Injector 1

Chemical Injector 2

Correct nozzle to use

Repairing chemical injector

The injector might be worn out or have something inside of the valve causing it not to ****. If you are using a new high pressure hose or a longer hose this may also have an effect over the injector not working.

First off you must be using the low pressure nozzle for the chemical injector to work. It will not work on high pressure. The spring goes into the injector body first with the ball in metering valve.

your chemical feed works on most units on low pressure. there should be a adjustment nob red on the intake unloader. if not its preset

Be sure that you have your chemical injector plumbed correctly. They will only work one way.