Before you begin. This procedure is general reference information, not professional advice. Equipment varies by manufacturer, model, and year. Always follow the documentation supplied with your equipment — where it differs from this page, follow the manufacturer. Verify that you have the tools, the working conditions, and the ability to do this task safely. If anything is unclear, if the equipment is damaged, or if the task exceeds your experience, stop and use a qualified professional. You are responsible for your own safety and for the outcome. This site accepts no liability for any loss, damage, or injury arising from the use of this information.
Specifications marked unverified could not be traced to a manufacturer source. Do not rely on them — obtain the value from your equipment documentation.
Summary
A pressure washer that will not spray soap has not necessarily failed. On most machines the detergent only draws through a dedicated low-pressure nozzle, usually black and marked Soap or Detergent, and every other nozzle on the machine will not draw it at all. Sun Joe's own manual for the SPX3000 states this directly: install the correct Soap nozzle, and all of the other coloured nozzles will not work for detergent application. Generac's gas-powered machines use a different mechanism, a siphon tube dropped into a bucket of premixed solution, but the same rule holds: detergent cannot be applied with a high-pressure nozzle. Fit the low-pressure nozzle first, and the soap that "isn't coming out" usually starts working immediately.
What may safely go through the tank or the tube is a separate, safety-critical question, and the two manufacturers we read are specific and blunt about it. Sun Joe's manual lists what never goes in: household detergents, acids, alkaline solutions, bleaches, solvents, flammable material, and industrial-grade cleaners, warning that these chemicals will harm the unit and damage the surface being cleaned. Generac's own note is shorter and just as firm: do not use caustic liquid, and use only power-washer-safe detergents, following the instructions on the detergent's own label. Both machines agree on the underlying principle even though their equipment differs, so this page states the principle and does not invent a single universal chemical list; read the label on your own detergent and the documentation for your own machine.
The step almost nobody does, and the one that actually causes most "dead" injectors, is flushing the system with clean water immediately after every use, not just before winter storage. Sun Joe's manual gives one minute through 1.3 gallons (5 litres) of fresh water for its tank system; Generac gives one to two minutes through a bucket for its siphon tube. Skip it and dried detergent residue blocks the tube or the tank outlet, so the next time you reach for the black nozzle nothing comes through it at all. This page covers that flush after every use; a separate page on this site covers preparing the whole pump for winter, which is a different job with its own antifreeze question.
Safety
DO NOT AIM THE SPRAY GUN AT A PERSON OR AN ANIMAL.
Fluid injection through skin can cause death or a serious injury. Generac names this hazard on its own machines.
Necessary equipment
| Item | Note |
|---|---|
| The manufacturer documentation for your machine | The documentation names the detergent type that the maker of your machine approves. |
| Eye protection | Wear eye protection when you handle detergent or start the machine. |
| Protective gloves | Wear protective gloves when you handle the detergent. |
| A container for clean water | Use this container for the flush after you finish with detergent. |
| Detergent designed for a pressure washer material | Use only detergent that the maker of your machine approves. |
| Clean water material | Use the clean water for the flush of the detergent system. |
Read the detergent label
Estimated 3 min to 7 min
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
- Find the detergent instructions in the manufacturer documentation for your machine.2mReport a problem with step 1, Read the detergent label
- Sun Joe puts these instructions on page 11 of the manual for the SPX3000.
- Generac puts these instructions on page 9 of the manual for its gas models.
- Read the label on the detergent product. Make sure that the label states the product is safe for a pressure washer.1mReport a problem with step 2, Read the detergent label
- Sun Joe requires a detergent designed for use with pressure washers.
- Generac requires a detergent that is safe for a power washer.
- If the label gives no such statement, do not use the product in the machine.<1mReport a problem with step 3, Read the detergent label
Fill the tank or place the siphon tube
Estimated 4 min to 6 min
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
USE ONLY DETERGENT THAT THE LABEL OR THE MAKER OF YOUR MACHINE APPROVES.
Avoid contact between the detergent and your skin or your eyes. Bleach, acid, ammonia, or a solvent can damage the pump and burn your skin or your eyes.
- Wear eye protection and protective gloves before you handle the detergent.<1mReport a problem with step 1, Fill the tank or place the siphon tube
- If your machine has a removable tank, pull the tank from its storage position.<1mReport a problem with step 2, Fill the tank or place the siphon tube
- Mix the detergent as the label directs, if the label gives a ratio. Fill the tank with the detergent.2mReport a problem with step 3, Fill the tank or place the siphon tube
- Sun Joe states that you must mix some detergents before use.
- Generac tells you to prepare the detergent solution as the job requires.
- Insert the suction tube into the tank. Close the cap. Return the tank to the storage position.<1mReport a problem with step 4, Fill the tank or place the siphon tube
- If your machine has a siphon tube, put the filter end of the tube into a container of the detergent.<1mReport a problem with step 5, Fill the tank or place the siphon tube
- Keep the filter and the tube under the surface of the detergent.<1mReport a problem with step 6, Fill the tank or place the siphon tube
- Generac warns that an exposed filter can stop the flow of detergent.
- Set the detergent selection dial to the tank or the rate you want, if your machine has one.<1mReport a problem with step 7, Fill the tank or place the siphon tube
- Sun Joe's dial also controls the rate of flow of the detergent.
Fit the low-pressure nozzle and apply the detergent
Estimated 7 min to 16 min
SQUEEZE THE TRIGGER ON THE TRIGGER GUN BEFORE YOU CHANGE THE NOZZLE.
Water under stored pressure in the wand can force a jet into your skin and cause a serious injury.
- Set the machine switch to off. Close the water supply tap. Squeeze the trigger to release the water pressure.<1mReport a problem with step 1, Fit the low-pressure nozzle and apply the detergent
- Engage the safety lock on the trigger gun.<1mReport a problem with step 2, Fit the low-pressure nozzle and apply the detergent
- Remove the fitted nozzle from the spray wand.<1mReport a problem with step 3, Fit the low-pressure nozzle and apply the detergent
- Install the nozzle marked for detergent on the spray wand.<1mReport a problem with step 4, Fit the low-pressure nozzle and apply the detergent
- Sun Joe names this the Soap nozzle and colours it black.
- Generac names this the Detergent nozzle and also colours it black.
MAKE SURE THAT THE NOZZLE LOCKS IN THE COLLAR BEFORE YOU START THE MACHINE.
A loose nozzle can leave the wand at speed. CPSC recorded a recall for this fault.
- Pull the nozzle to make sure that the collar holds it.<1mReport a problem with step 5, Fit the low-pressure nozzle and apply the detergent
- Open the water supply tap. Start the machine. Release the safety lock on the trigger gun.<1mReport a problem with step 6, Fit the low-pressure nozzle and apply the detergent
- Do a test of the detergent on a hidden area.<1mReport a problem with step 7, Fit the low-pressure nozzle and apply the detergent
- Sun Joe tells an operator to do a test of the detergent in an inconspicuous area before use.
- Squeeze the trigger to apply the detergent to a dry surface, from the bottom to the top.3mReport a problem with step 8, Fit the low-pressure nozzle and apply the detergent
- Sun Joe and Generac both give this direction for detergent application.
DO NOT LET THE DETERGENT DRY ON THE SURFACE.
Dried detergent can damage a painted surface. Sun Joe states that the damage can occur on painted surfaces.
- Let the detergent stay on the surface for a short time.1mReport a problem with step 9, Fit the low-pressure nozzle and apply the detergent
- Do not let the detergent dry on the surface.
Flush the detergent from the system
Estimated 11 min to 18 min
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
FLUSH THE SYSTEM WITH CLEAN WATER AFTER EVERY USE.
Dried detergent can block the tank or the tube. The system can lose the ability to draw detergent.
- Set the machine switch to off. Squeeze the trigger to release the water pressure. Engage the safety lock.<1mReport a problem with step 1, Flush the detergent from the system
- Remove the detergent nozzle from the spray wand.<1mReport a problem with step 2, Flush the detergent from the system
- Install a high-pressure nozzle. Rinse the surface to remove the detergent.4mReport a problem with step 3, Flush the detergent from the system
- See our nozzle-selection page for the method to rinse a surface.
- Set the machine switch to off. Squeeze the trigger to release the water pressure. Engage the safety lock.<1mReport a problem with step 4, Flush the detergent from the system
- Remove the high-pressure nozzle. Install the nozzle marked for detergent.<1mReport a problem with step 5, Flush the detergent from the system
- If your machine has a tank, remove the suction tube from the detergent. Insert the tube into a container of clean water.1mReport a problem with step 6, Flush the detergent from the system
- Sun Joe gives a fresh water quantity for this step. See the specification below for the figure.
- If your machine has a siphon tube, place the filter end of the tube into a container of clean water.<1mReport a problem with step 7, Flush the detergent from the system
- Generac gives a bucket of clean water for this step.
- Open the water supply tap. Start the machine. Release the safety lock on the trigger gun.<1mReport a problem with step 8, Flush the detergent from the system
- Squeeze the trigger to draw the clean water through the system.1mReport a problem with step 9, Flush the detergent from the system
- Sun Joe gives one minute for its own tank system.
- Generac gives one to two minutes for its own siphon tube.
- Use the time in the documentation for your own machine.
- Set the machine switch to off. Squeeze the trigger to release the water pressure. Engage the safety lock.<1mReport a problem with step 10, Flush the detergent from the system
- Remove the container. Rinse it with clean water.<1mReport a problem with step 11, Flush the detergent from the system
- Sun Joe tells you to rinse the detergent bottle until it is clean.
- Turn the detergent selection dial to the centre position, if your machine has one.<1mReport a problem with step 12, Flush the detergent from the system
Stop the machine
Estimated 2 min
- Close the water supply tap.<1mReport a problem with step 1, Stop the machine
- If your machine is electric, remove the plug from the socket.<1mReport a problem with step 2, Stop the machine
- If your machine has an engine, follow the shutdown steps in your documentation.<1mReport a problem with step 3, Stop the machine
- Empty any unused detergent from the tank or the container.<1mReport a problem with step 4, Stop the machine
- Sun Joe tells an owner to empty the detergent bottle before storage.
- Store the detergent in its own closed container, away from children and animals.<1mReport a problem with step 5, Stop the machine
Terminology
This page uses one term for each item and holds it throughout, as ASD-STE100 requires. Equipment sellers and other guides use the names below for the same parts.
- detergent injector
- Also called: soap injector, chemical injector, detergent siphon, injector system, the soap thing on my pressure washer, downstream injector
- detergent nozzle
- Also called: soap nozzle, black nozzle, black tip, soap tip, chemical nozzle, low pressure nozzle
- siphon tube
- Also called: suction tube, pickup tube, chemical hose, the little tube that goes in the bottle, detergent hose
- pressure washer
- Also called: power washer, jet washer, jet wash, karcher, power hose
- pressure washer detergent
- Also called: car wash soap, pressure washer soap, power washer chemical, cleaning solution
When to use a professional
Stop if the water jet touches your skin and breaks it. Do not wait for pain. Go to an emergency department immediately. Tell the medical staff that a pressure washer caused the wound.
Stop if detergent touches your eyes or your skin and does not rinse away easily. Flush the area with much clean water. Then get medical aid. In the United States, call the Poison Help line at 1-800-222-1222 if a person swallows detergent.
Stop if the label on the detergent gives no statement about a pressure washer. Do not guess. Speak to the maker of the detergent or the maker of your machine.
Stop if the detergent still does not draw once you fit the correct nozzle. Flush the system again. Do not force the tube or the tank. Speak to the maker of your machine.
Stop if a nozzle does not lock in the collar. Do not hold a nozzle on the wand with your hand. Speak to the maker of your machine. CPSC recorded a recall in 2020 for a nozzle that disconnected from a wand.
Stop if the machine has a damaged hose, a damaged trigger gun, or a damaged wand. Do not repair a hose. Speak to a service dealer.
Common questions
Why is no soap coming out of my pressure washer?
Because on most machines the detergent only draws through a dedicated low-pressure nozzle, and every other nozzle will not draw it at all. Sun Joe's manual for the SPX3000 states it directly: install the correct Soap nozzle, black in colour, and all of the other coloured nozzles will not work for detergent application. Generac's gas machines use a siphon tube instead of a tank, but the same rule applies: detergent cannot be applied with a high-pressure nozzle, only with the black Detergent nozzle. People often conclude the injector has failed when the real fix is a nozzle change. Fit the correct nozzle, confirm the detergent selector is not set to off, and try again before you assume anything is broken.
What is a pressure washer detergent injector, exactly?
It is whatever draws detergent into the water stream at low pressure, and the mechanism differs by machine. On the Sun Joe SPX3000 it is a pair of removable tanks with a selector dial that also sets the flow rate. On Generac's gas-powered models it is a siphon tube with a filter on the end, which you place directly into a bucket or a bottle of premixed solution. Both designs only draw detergent when a matching low-pressure nozzle is fitted; neither draws anything through a high-pressure nozzle. Read the description in your own manual before you assume your machine works like either of these two.
Can I use bleach in a pressure washer?
Sun Joe's own manual says no, in as many words: its list of chemicals never to use names bleach, chlorine products, and other corrosive chemicals first, alongside solvents, ammonia products, and acid-based products, and states plainly that these chemicals will harm the unit and will damage the cleaning surface. Generac's manual is shorter but points the same way: do not use caustic liquid with the power washer, and use only power-washer-safe detergents. Neither company is describing every pressure washer ever built, and pump seal material differs between manufacturers, so this is not a blanket promise that bleach is safe in some other machine. Read the label on your detergent and the chemical guidance in your own machine's documentation before you put anything other than water or an approved detergent through the tank or the tube.
What is the black nozzle for, and does the colour mean the same thing on every machine?
On the two machines we read for this page, black means detergent on both of them: Sun Joe calls it the Soap nozzle, and Generac calls it the Detergent nozzle. That agreement is worth noting because the two makers do not agree on other nozzle colours -- see our nozzle-selection page for that disagreement in full. Even where the colour matches, read the mark on the nozzle itself or the table in your own manual rather than trusting memory, because a mismatched nozzle either will not draw detergent or will draw it at the wrong rate.
Can I use dish soap or laundry detergent instead of buying a pressure washer detergent?
Not according to either manual we read for this page. Sun Joe's list of prohibited chemicals includes household detergents by name, and Generac's instruction is to use only power-washer-safe detergents and to follow the instructions on the detergent's own label -- a laundry or dish product carries no such label. Household detergents are often formulated to foam heavily, and a pump built for a thin, low-foam chemical can be affected by how much it draws and meters. Buy a product labelled for use in a pressure washer, and treat anything else as unverified for your machine.
Why do I have to flush the system after every single use?
Because detergent that dries inside the tube or the tank outlet blocks it, and a blocked injector is a leading cause of a pressure washer that stops drawing detergent. Sun Joe's manual states this outright: failure to follow the cleaning instructions will cause the injection system to become clogged and inoperable, and its fix is to draw 1.3 gallons (5 litres) of fresh water through the system for one minute after every use. Generac gives the same kind of instruction for its own siphon-tube design, flushing for one to two minutes through a bucket of clean water. Neither company treats this as optional or as a once-a-season job -- it is a step for every time you use detergent, however short the job was.
Is this the same as winterizing the pump?
No, and the two jobs are easy to conflate because both involve pushing clean fluid through the detergent path. Winterizing protects the whole pump against a hard freeze, once a year, with a fluid the manufacturers we researched for that page do not agree on -- see our winterizing page for that separate question. This page is about the ordinary end-of-job flush with plain water, which you do every time you use detergent, whatever the season. Do this flush after every job, and do the winterizing job separately before the first frost.
The detergent still will not draw, even with the correct nozzle fitted. What now?
Confirm the basics first: the correct low-pressure nozzle is fitted, the detergent selector is not turned to off, and the filter on the tube or in the tank is under the surface of the liquid, not sitting above it. If all of that is correct and detergent still does not draw, the tube, the filter, or the valve inside the system may be blocked or damaged, and this page does not cover opening that part of the machine. Speak to the maker of your machine or to an authorized dealer rather than forcing a part that resists.
Related procedures
- How to choose the right pressure washer nozzle for the surface you are cleaning, and what the colours actually mean
- Clear a blocked pressure washer nozzle and inlet screen
- How to check and change pressure washer pump oil, and how to tell if your pump even has oil
- How to winterize a pressure washer pump before freezing weather, and what to put in it
- Inspect a pressure washer hose, couplings and O-rings before use
- Check that a water supply can feed a pressure washer before the machine is started
- Find the safety data sheet for a chemical product you already own, and read the parts that matter
- How to find and record the model and serial number of every appliance in the house
Sources
Every specification on this page is traced to one of these sources. Tier 1 is a manufacturer document, a published standard, or a government safety authority. See Standards for the full tiering rule.
- Tier 1Sun Joe SPX3000 Electric Pressure Washer Operator's Manual (MR15, 06272023)
- Tier 1Small Pro Power Washer Owner's Manual (document G0069240, covers 3200-3600 PSI gas pressure washer models)
- Tier 1STIHL Recalls Pressure Washers Due to Injury Hazard (Recall 20-057)
Revision history
Current version 1 · updated 2026-08-04 · next review due 2027-08-04
- v1 · 2026-08-04First draft. Sourcing band tier1-per-unit confirmed: two machine-maker operator manuals were fetched directly from the manufacturer's own URL this session (Sun Joe SPX3000, pages 10-13; Generac Small Pro Power Washer, manual's own pages 6-10) and read in full with pdftotext extraction, both already registered in data/sources.json from earlier sessions for other topics. Both manuals independently state the same chemical-compatibility principle -- only a detergent made for a pressure washer, never bleach, acid, ammonia, or a solvent -- so the specification publishes that principle as an instruction rather than either maker's specific banned-substance list, since chemical compatibility is per-machine and per-pump (rule 1). The two makers give different flush durations and water quantities for their own different injector designs (Sun Joe: 1 minute, 1.3 gal/5 L, tank system; Generac: 1-2 minutes, a bucket, siphon-tube system); the disagreement is published in a conflict_note naming both rather than averaged. No new sources were staged: all three cited sources (both manuals plus the CPSC STIHL nozzle recall, reused for the nozzle-lock hazard) were already admitted to the registry from earlier drafting sessions. This page is scoped to routine detergent use and the after-every-use flush; it deliberately does not duplicate the full nozzle-selection method (see choose-a-pressure-washer-nozzle) or the seasonal pump-winterizing flush (see winterize-a-pressure-washer-pump), and points to both.
Corrections to this page are listed in the public corrections log. Reports that are credible and not yet verified are listed in the public errata register, and an open one renders above the step it concerns.
Comments and corrections
Found an error? A correction with a manufacturer source is applied and logged publicly. You can also write to corrections@fixchecklist.com.
Every step above carries its own report control, which tags the report with that step so a correction reaches the right place. For anything about the procedure as a whole — the order of the sections, a step that is missing, something that did not match your equipment — use this: report something about this whole procedure.