Jabsco Par-Max HD Heavy-Duty Freshwater Pump — 12V, 4.0 GPM, Cast Aluminum Housing (Q401J-118-S3A)
Free returns on all eligible orders
You have 30 days to request a return. All sale items are final sale.
Jabsco Par-Max HD Heavy-Duty Freshwater Pump — 12V, 4.0 GPM
A pressure switch variant of the Par-Max HD 4 GPM platform. The Jabsco Par-Max HD Q401J-118-S3A delivers 4.0 GPM at 12V with a heavy-duty motor and cast aluminum lower housing — built for two-to-three-fixture freshwater systems on mid-size cruisers where the 3 GPM HD is at its limit and the 5 GPM is more than needed. The co-molded diaphragm, integrated bypass module, and sealed pressure switch deliver smooth, on-demand operation, and the Quick Connect Strainer is included. Self-priming, run-dry safe, and quiet thanks to vibration-dampening mounting feet.
Note: This is a pressure switch variant of the Par-Max HD 4 GPM platform. Confirm the correct pressure switch specification for your system before ordering — see also the Q401J-115-S3A variant if you need a different switch setting.
Key Features
- 4.0 GPM flow rate at 12V DC — mid-range output in the Par-Max HD series
- Heavy-duty motor and cast aluminum lower housing — built for long life at high pressures and demanding duty cycles
- Integrated bypass module — reduces pump cycling and provides smoother flow
- Quick Connect Strainer included — protects pump from supply line debris
- Co-molded diaphragm technology for long service life and durability
- Integrated, sealed pressure switch for automatic on-demand operation
- Quick-connect ports for fast installation, servicing, and maintenance
- Vibration-dampening mounting feet for quiet operation
- Self-priming — flexible installation without manual priming
- Run-dry capable — no damage if the tank runs empty
Compatible Applications
- Two-to-three-fixture freshwater systems on mid-size powerboats, sailboats, and cruisers
- High-pressure freshwater systems requiring more output than the HD 3 GPM provides
- 12V DC installations requiring cast aluminum construction for long-term reliability
- Systems where the HD 5 GPM is more output than required
Parts Desk Insights
If you’re choosing between the two Par-Max HD 4 GPM variants, confirm the pressure switch specification your system requires — the Q401J-115-S3A is the companion variant at the same price point. The Par-Max HD 4 GPM is the practical mid-range option for mid-size cruisers with a galley, head, and occasional third fixture. For lower output in the HD series, the Par-Max HD 3 GPM (Q301J-115-S3A) is the step-down. For higher output, the Par-Max HD 5 GPM and Par-Max HD 6 GPM are the step-ups. Add a GROCO PST-1 Accumulator Tank or Jabsco Accumulator Tank downstream to smooth pressure delivery and reduce pump cycling.
Part Number: Q401J-118-S3A | Voltage: 12V DC | Flow Rate: 4.0 GPM | Housing: Cast Aluminum | Includes: Bypass Module & Quick Connect Strainer
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 1-3 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.