6 Best General Pump Downstream Injectors (October 2026)
The best General Pump downstream injectors include the General Pump 3-5 Gpm Chemical Injector for 3–5 GPM washers, the YAMATIC Adjustable Chemical Injector Kit for adjustable draw, and the JOEJET Fixed Downstream Injector for Pressure Washer for a ready-to-connect kit.
On this page (7 sections)
- How we chose a General Pump downstream injector
- Best General Pump downstream injectors for each flow range
- How do you match injector flow to washer flow?
- Which connection details should you verify?
- When is an adjustable injector useful?
- How can you troubleshoot weak chemical draw?
- Which General Pump injector should you choose?
The best General Pump downstream injector for a 3–5 GPM washer is the General Pump 3-5 Gpm Chemical Injector. For a 2–3 GPM machine, choose its lower-flow model; for 5–8 GPM, compare the two higher-flow General Pump options.
Flow rate is the first filter, but it isn't the only one. Connection type, pressure rating and whether you need an adjustable kit can change which injector fits your washer.
Our picks at a glance
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1
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2
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3
Best for a ready-to-connect kitJOEJET Fixed Downstream Injector for Pressure Washer
9.5/10 our score
See it on Amazon
- 4Check it
General Pump Fixed Chemical Injector
Best for 5–8 GPM washers - 5
Check itGeneral Pump 2-3 Gpm Chemical Injector
Best for 2–3 GPM washers - 6
Check itGeneral Pump 2.3mm Pressure Washer Detergent Injector
Best for 5–8 GPM threaded setups
How we chose a General Pump downstream injector
The right injector matches your washer's flow range and connection style, with chemical draw and kit contents as secondary factors. We compared the listed configurations and included a couple of non-General Pump options for readers who want an adjustable valve or a complete quick-connect kit.
Our score weighs specs and features against the needs of someone shopping for a General Pump downstream injector. We did not test these injectors.
If you're new to soap injection, How Does a Pressure Washer Soap Injector Work? explains the basic flow path.
| Product | Best for | Flow range | Connection | Draw | Our score |
|---|---|---|---|---|---|
| General Pump 3-5 Gpm Chemical Injector | 3–5 GPM washers | 3–5 GPM | Threaded inlet; 1/4 in NPT outlet | High draw, up to 20% | 9.7 |
| YAMATIC Adjustable Chemical Injector Kit | adjustable draw | 2–5 GPM | 3/8 in quick connect | 9.6 | |
| JOEJET Fixed Downstream Injector for Pressure Washer | a ready-to-connect kit | 3–5 GPM | 3/8 in quick connect adapters | 9.5 | |
| General Pump Fixed Chemical Injector | 5–8 GPM washers | 5–8 GPM | 3/8 in NPT male inlet and outlet | High draw, up to 20% | 9.0 |
| General Pump 2-3 Gpm Chemical Injector | 2–3 GPM washers | 2–3 GPM | 8.7 | ||
| General Pump 2.3mm Pressure Washer Detergent Injector | 5–8 GPM threaded setups | 5–8 GPM | 3/8 in NPT male inlet and outlet | High draw up to 20% | 8.5 |
Best General Pump downstream injectors for each flow range
The 3–5 GPM General Pump model is the broadest fit among the brand's options here, while the 2–3 and 5–8 GPM models target narrower flow bands. Match the range to your washer's rated output before comparing body style or draw.
General Pump 3-5 Gpm Chemical Injector: Best for 3–5 GPM washers
- 3–5 GPM flow range
- Fixed chemical injector
- High draw up to 20%
- Brass body
A direct match for a washer in the 3–5 GPM range. Check the connections on your washer and hose before choosing this body-only injector.
Pros
- Stated 3–5 GPM range
- High draw up to 20%
- Brass body
Cons
- Body only
- Confirm connection fit before buying
The 100775 is the most direct pick for a washer rated between 3 and 5 GPM. General Pump identifies it as a fixed, high-draw chemical injector, with chemical draw up to 20%.
This is a brass body only, so plan to use a compatible hose and fittings. Its connections are described as a threaded inlet and a 1/4 in NPT outlet.
Check your washer's outlet and hose ends before buying, since connection fit is separate from flow fit.
A downstream injector draws chemical into the water stream after the pump. Read [What Is a Downstream Injector?
A Full Breakdown](/what-is-a-downstream-injector/) for the parts and low-pressure conditions that affect soap draw.
Choose this model if your washer runs 3–5 GPM and you can match the threaded connections. It is not the best pick for a 2 GPM machine or for a washer whose connections require a 3/8 in quick-connect kit.
YAMATIC Adjustable Chemical Injector Kit: Best for adjustable draw
- Adjustable water flow from 2–5 GPM
- 3/8 in quick connects
- Siphon hose and soap nozzle included
- Requires low-pressure use
An adjustable kit for washers within its 2–5 GPM range. It includes a siphon hose and soap nozzle, and needs low-pressure operation to draw chemical.
Pros
- Metering valve adjusts dilution
- Includes siphon hose and soap nozzle
- Stainless steel and brass construction
Cons
- Requires a large-orifice black soap nozzle
- Confirm 3/8 in connections fit your setup
YAMATIC's kit suits buyers who want adjustable dilution and quick-connect fittings in one package. Its metering valve adjusts water flow across a stated 2–5 GPM range.
The kit uses 3/8 in quick connects and includes a siphon hose and soap nozzle. For model-specific soap instructions, see Greenworks washer soap guide.
YAMATIC says it draws chemical only at low pressure, 250 PSI or less, and requires a large-orifice black soap nozzle.
Confirm that your washer and hose use compatible 3/8 in connections.
The kit's stated maximum working pressure is 4500 PSI, but that does not remove its low-pressure requirement for chemical draw. Use the operating conditions specified for soap application.
Pick it if you want an adjustable kit for a 2–5 GPM washer. Skip it if you need a fixed General Pump injector or your setup cannot use the 3/8 in quick connects.
JOEJET Fixed Downstream Injector for Pressure Washer: Best for a ready-to-connect kit
- 3–5 GPM flow rate
- 3/8 in quick connects
- Rated up to 3200 PSI
- Siphon hose and filter included
This fixed injector suits 3–5 GPM washers and includes adapters, a siphon hose, filter and black soap nozzle. Check that its 3200 PSI maximum fits your washer.
Pros
- Adapters and hose included
- Stated 3–5 GPM range
- Brass and stainless steel construction
Cons
- Fixed rather than adjustable
- Maximum pressure is 3200 PSI
JOEJET's fixed injector is another option for 3–5 GPM washers, with the adapters and soap-draw parts included. Its package lists a 10 ft siphon hose, filter, black soap nozzle and 3/8 in quick-connect adapters.
The injector is made from brass and stainless steel and is rated up to 3200 PSI. Make sure that limit suits your washer, and align the arrow with water flow during installation, as JOEJET instructs.
Because it is a kit, it may reduce the need to source fittings separately. Its fixed design does not offer the metering adjustment available on the YAMATIC kit.
Choose it if you want a 3–5 GPM package with a hose, filter and nozzle. Check the pressure rating and adapter fit before installation.
General Pump Fixed Chemical Injector: Best for 5–8 GPM washers
- 5–8 GPM flow range
- High draw up to 20%
- 3/8 in NPT connections
- Rated up to 4500 PSI
This General Pump injector is sized for higher-flow washers at 5–8 GPM. Its 3/8 in NPT male connections call for a compatible threaded setup.
Pros
- Stated 5–8 GPM range
- High draw up to 20%
- Brass body
Cons
- Not sized for most lower-flow washers
- Body only
This General Pump injector is intended for higher-flow washers from 5 to 8 GPM. It has a brass body, high chemical draw up to 20%, and 3/8 in NPT male inlet and outlet connections.
The maximum pressure rating is 4500 PSI, and the maximum temperature rating is 190°F. Those limits matter when matching the injector to a hot-water or high-pressure setup.
The injector is a body only, so you need compatible fittings and a siphon hose.
Choose this model if your machine flows 5–8 GPM and uses 3/8 in NPT connections. A lower-flow washer needs an injector sized for its own range.
General Pump 2-3 Gpm Chemical Injector: Best for 2–3 GPM washers
- 2–3 GPM flow range
- General Pump part 100774
- Compact injector body
Choose this model when your washer's flow falls between 2 and 3 GPM. Verify the connection type and size for your setup before ordering.
Pros
- Stated 2–3 GPM range
- General Pump model 100774
Cons
- Connection details need confirmation
The General Pump 100774 is the lower-flow option for washers rated 2–3 GPM. Its model number is 100774, and the product is identified as a General Pump chemical injector.
Connection details are not established here, so compare the injector with your machine's outlet and hose before buying. Do not assume it uses the same fitting arrangement as the 3–5 GPM 100775.
This simple choice makes sense when your washer's rated flow is below the 3–5 GPM range. The priority is confirming both GPM and connection fit, since either mismatch can stop the injector from working with your setup.
Choose it for a 2–3 GPM washer once you've confirmed the connections. For higher output, move to a model whose range includes your machine's rated flow.
General Pump 2.3mm Pressure Washer Detergent Injector: Best for 5–8 GPM threaded setups
- 5–8 GPM flow range
- 2.3 mm injector
- 3/8 in NPT male connections
- Rated up to 4500 PSI
This 2.3 mm General Pump injector suits 5–8 GPM washers with compatible 3/8 in NPT male connections. Compare its configuration with the fixed 5–8 GPM option above.
Pros
- Stated 5–8 GPM range
- 2.3 mm injector
- 3/8 in NPT male connections
Cons
- Threaded connections need a matching setup
- Body only
This 2.3 mm General Pump injector is another 5–8 GPM option, with 3/8 in NPT male inlet and outlet connections. It is rated up to 4500 PSI and up to 190°F.
The listed flow range overlaps the 100776 configuration, so compare the connection details and exact model you need before ordering. Both options are fixed injectors with high draw up to 20%, but this one specifies a 2.3 mm orifice.
Its threaded connections suit setups that accept 3/8 in NPT male fittings. If your machine uses quick connects, you may need compatible adapters.
Choose it when the 2.3 mm configuration and 3/8 in NPT connections match your washer. Consider the other 5–8 GPM General Pump injector if you are comparing a simpler fixed body.
How do you match injector flow to washer flow?
Match the injector's GPM range to the washer's rated water flow, not just its pressure rating. A 3–5 GPM injector is not a general fit for every pressure washer.
The options here break down into three bands: 2–3 GPM, 3–5 GPM and 5–8 GPM. If your washer's flow is near a boundary, check its manual or nameplate and confirm how the manufacturer states its operating GPM.
A higher PSI rating does not mean an injector will draw chemical on every nozzle setting. For brand-specific soap steps, see Ryobi washer soap guide.
Some downstream injectors need a low-pressure soap nozzle to create the conditions for siphoning.
Which connection details should you verify?
Check both ends of the injector against the washer outlet and pressure hose before buying. Threaded NPT parts and 3/8 in quick connects are different connection styles, even when their nominal size sounds similar.
The General Pump 3–5 GPM model has a threaded inlet and 1/4 in NPT outlet. The two 5–8 GPM General Pump options use 3/8 in NPT male inlet and outlet connections, while the YAMATIC and JOEJET kits use 3/8 in quick-connect fittings or adapters.
If your setup needs another material or style, compare the best stainless steel downstream injectors for alternatives. Check the exact fitting arrangement for your machine before ordering, especially when an injector is sold as a body only.
When is an adjustable injector useful?
An adjustable injector is useful when you want to change the dilution setting without swapping a fixed injector. YAMATIC's metering valve adjusts water flow across a stated 2–5 GPM range.
That adjustment does not replace the need to use a suitable low-pressure soap nozzle. YAMATIC specifies a large-orifice black nozzle and operation at 250 PSI or less for chemical application.
If you only need a fixed injector matched to a specific GPM band, a General Pump model may be simpler. For a broader look at styles and fit, see our best pressure washer detergent injector guide.
How can you troubleshoot weak chemical draw?
Weak draw often points to a mismatch in nozzle, flow, hose setup or chemical thickness. Start with the injector's required nozzle and pressure conditions, then check that the siphon hose and filter are clear.
YAMATIC advises using thin soap, similar to water, and notes that raising the chemical container briefly may help establish a siphon. It also suggests cleaning or soaking the injector in warm water if it is clogged.
JOEJET says the arrow on its fixed injector must follow the direction of water flow. If the injector still fails to draw, check the model's instructions and verify that your washer's flow falls within its stated range.
Which General Pump injector should you choose?
Choose the 100775 for 3–5 GPM, the 100774 for 2–3 GPM, and one of the 5–8 GPM models for higher-flow washers. If adjustable dilution and a complete quick-connect kit matter more than a General Pump body, consider the YAMATIC option.
Start with flow, then confirm connections and low-pressure requirements. That sequence narrows the choice to an injector that can fit your washer and draw soap under the right conditions.
Our top 3 picks at a glance
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1
-
2
-
3
Best for a ready-to-connect kit
JOEJET Fixed Downstream Injector for Pressure Washer
9.5/10 our score
See it on Amazon
Frequently asked questions
What GPM injector should I use?
Choose an injector whose stated flow range includes your pressure washer's GPM. The General Pump options here cover 2–3, 3–5 and 5–8 GPM ranges.
Also check connection type, size and pressure limits, since a flow match alone does not confirm that an injector fits your washer.
Do downstream injectors need a black soap nozzle?
Some setups require a low-pressure soap nozzle to draw chemical. YAMATIC specifies a large-orifice black soap nozzle and operation at 250 PSI or less.
Check the instructions for your injector and use the nozzle suited to its requirements.
What is the difference between fixed and adjustable injectors?
A fixed injector has a set configuration, while an adjustable injector lets you change the chemical dilution through a metering valve. YAMATIC describes an adjustable water-flow range of 2–5 GPM.
Choose based on whether adjustment matters and whether the injector fits your washer's flow and connections.
How do I check a downstream injector's dilution ratio?
Measure the water and detergent used during the same run. JOEJET describes placing the washer's water inlet in one bucket and the injector's filter in a detergent bucket, then comparing how much each loses.
The result depends on your washer's flow and setup.
