Craftsman 390291601 captive air tank & fittings Parts

Most water pumps, including common setups used with a Craftsman 390291601 captive air tank and fittings, are built around seven core components: a power source (motor), an impeller, a pump casing, a shaft, bearings, a mechanical seal, and inlet/outlet ports that connect to your plumbing.

The 7 major parts (what each one does)

• Motor (power source): Spins the pump shaft to create water movement.
• Impeller: The rotating “fan” that pushes water through the pump.
• Pump casing (volute/housing): Directs flow and converts impeller energy into pressure.
• Shaft: Transfers motor rotation to the impeller.
• Bearings: Support the shaft so it spins smoothly and stays aligned.
• Mechanical seal (or seal set): Keeps water from leaking along the shaft.
• Inlet and outlet ports: The suction and discharge connections for piping or fittings.

Quick identification guide (symptom to likely area)

What you notice	Most likely part area	What we check first
Pump runs but low flow/pressure	Impeller, casing, inlet	Clogs, debris, air leaks on suction side
Water leaking near the motor/pump seam	Mechanical seal	Wetness at shaft area, seal wear
Loud grinding or squeal	Bearings, shaft	Shaft play, bearing noise, misalignment
Hard starting or trips breaker	Motor, wiring	Power supply, capacitor (if equipped), wiring condition

Why it matters

Knowing these seven parts helps us troubleshoot faster: most “no water,” “low pressure,” or “leak” complaints trace back to suction-side air leaks, a worn seal, or an impeller/casing issue rather than the entire pump needing replacement.

Helpful DIY prep before you troubleshoot

• Shut off power at the breaker before touching wiring
• Relieve system pressure and drain water where needed
• Confirm the suction line is airtight (even small leaks can stop prime)
• Check for debris at the inlet/strainer (if your setup uses one)
• Use the correct model number when looking up diagrams and parts

For model-based parts lookup and diagrams, we use the model number 390291601; you can also search by model on Sears PartsDirect.

Last updated: February 2026

On a Craftsman water pump setup like model 390291601, the pump connects to both water-handling parts (inlet and outlet plumbing) and drive/sealing parts (shaft, seal, bearings). These connections move water, keep pressure stable, and prevent leaks.

Common parts connected to the pump

Most water pumps use the same core component groups:

• Suction (inlet) line: pipe or hose from the water source to the pump inlet
• Discharge (outlet) line: pipe or hose carrying water away from the pump
• Pump casing (housing): the body that contains the impeller and directs flow
• Impeller or diffuser/jet components (pump-type dependent): creates flow and pressure
• Shaft and coupling (or direct-drive interface): transfers motor power to the impeller
• Seal(s) and gasket(s): keep water from leaking along the shaft or at housing joints
• Bearings: support the shaft and keep it running smoothly

How the connections work (quick reference)

Connection area	What it connects to	What it does
Inlet (suction)	Suction pipe, foot valve/strainer (if used)	Feeds water to the pump and helps hold prime
Outlet (discharge)	Discharge pipe, check valve (if used)	Sends pressurized water to the system
Drive side	Motor, coupling, shaft	Spins the impeller to move water
Sealing surfaces	Mechanical seal, O-rings, gaskets	Prevents leaks and air entry

Why it matters

If any connected part leaks air (especially on the suction side) or restricts flow, the pump can lose prime, cycle rapidly, or deliver low pressure. Knowing what connects where helps you pinpoint whether the issue is plumbing, sealing, or the pump’s internal components.

Parts lookup and ordering tip

For model 390291601, match parts by the exact model number and the pump’s diagram location to avoid ordering the wrong seal, gasket, or fitting. If you are searching beyond the parts list for this model, use 390291601 on Sears PartsDirect.

Last updated: February 2026

In most cases, we repair a Craftsman water pump system by replacing the failed component (such as the pump, seal, pressure switch, or tank fittings) rather than “rebuilding” the pump itself, because many pump assemblies are effectively sealed and wear parts are not serviced individually.

What you can realistically repair vs. replace

Many “water pump problems” are actually caused by a serviceable external part, not the pump body.

• Repair (common): replace leaking fittings, a bad pressure switch, a failed capacitor, or damaged wiring
• Replace (common): pump assembly when the housing is cracked, the impeller is damaged, or internal seals/bearings are worn
• Rebuild (uncommon): only when a rebuild kit is available for your exact pump design and the pump body is in good shape

Quick checks before you buy parts

These checks help you avoid replacing the pump when the issue is power, controls, or plumbing.

• Verify the outlet has power and the breaker is not tripped
• Inspect the cord, plug, and visible wiring for heat damage or breaks
• Check for suction-side air leaks (loose clamps, cracked hose, bad thread seal)
• Confirm the tank holds pressure; rapid pressure loss points to a leak or check valve issue
• Listen for motor hum without pumping (often points to start capacitor or mechanical binding)

Symptom-to-fix guide

Symptom	Most likely cause	Typical fix
Pump runs but won’t build pressure	Air leak on suction side, clogged inlet, worn internal pumping parts	Seal leaks, clear blockage, replace pump if internal wear
Pump short-cycles	Waterlogged tank, pressure switch issue, system leak	Service tank/fittings, replace switch, fix leaks
Water leaking at pump	Loose fitting, cracked housing, failed seal	Reseal fitting, replace pump if housing/seal is not serviceable
Motor hums then trips	Bad capacitor, seized pump, low voltage	Test capacitor, free/replace pump, correct power issue

Why it matters

Replacing only the failed component restores pressure and flow while preventing motor overheating, breaker trips, and repeated cycling that shortens the life of the pump and captive air tank.

For Craftsman model 390291601, we recommend matching parts by the full model number when you shop; start with the parts list for this model, or search by model at Sears PartsDirect.

Last updated: February 2026

For a Craftsman 390291601 captive air tank and fittings setup, a “water pump replacement” usually means replacing the pump assembly and any sealing and connection parts that are disturbed during removal. We match the exact parts to your configuration when you search by model on Sears PartsDirect.

Parts and supplies you typically need

• Replacement pump (or pump head/assembly, depending on what failed)
• New O-rings, gaskets, or seals for any opened joints
• Thread sealant (PTFE tape or pipe thread sealant rated for water systems)
• New fittings or unions if existing threads are corroded or cracked
• Pressure switch or pressure gauge (only if testing shows they are faulty)
• Pipe nipple or short hose/connector (only if damaged during removal)

Tools that make the job go smoother

• Adjustable wrench and/or open-end wrenches
• Socket/ratchet set
• Screwdrivers
• Bucket or drain pan and towels
• Multimeter (for electrical checks)

Quick checklist before you order parts

Check	What to confirm	Why it matters
Power type	120V vs 240V motor setup	Prevents ordering an incompatible pump/motor
Port size	Commonly 1/4 in., 3/8 in., 1/2 in., or 3/4 in. NPT	Ensures fittings and unions match
Leak location	Housing seam, drain plug, fittings, or shaft area	Helps decide seal kit vs full pump
Symptoms	No prime, low pressure, short cycling	Points to pump vs pressure switch/tank issues

Why it matters

Water pumps and tank fittings seal under pressure; reusing flattened gaskets or damaged threads often causes leaks, air ingestion, and short cycling. Replacing seals and using the right thread sealant prevents repeat failures.

Helpful DIY reading

If you are also troubleshooting wiring, our guide on how to use a multimeter to test electrical parts video helps you confirm whether the issue is the motor circuit, pressure switch, or a connection.

Last updated: February 2026