If your well pump runs but no water comes out, you are almost certainly facing a loss of prime. As a professional Well Pump manufacturer with decades of engineering, production, and field-service experience across surface pumps, submersible pumps, solar pumps, and gas/diesel pumps, Jingong Technology has guided thousands of homeowners, farmers, irrigation contractors, and distributors through the priming process. This definitive guide explains what priming is, why it matters, which pumps need it, how to do it step-by-step, and how to prevent it from happening again — written from the perspective of a Well Pump manufacturer who knows every product category inside out.

Introduction — What Is Well Pump Priming and Why Every Well Pump Manufacturer Insists on It

Well pump priming (also called “filling the pump,” “charging the pump,” or “removing air from the system”) means manually filling the pump casing and the suction pipe with water (or the pumped fluid) and venting all trapped air before startup. A centrifugal or jet pump cannot lift water if air is trapped inside — it can only push liquid. Without a solid water column, the impeller spins against air, generates no pressure differential, and the pump fails to move water.

Why Priming Is Absolutely Essential

Every reputable Well Pump manufacturer emphasizes priming because the physics are unforgiving:

• Air Lock: Zero fluid movement despite the motor running. The pump spins, but nothing flows.
• Cavitation: Vapor bubbles form and violently collapse inside the casing, pitting the impeller and destroying the mechanical seal.
• Dry Running: Excessive heat buildup leads to motor burnout and bearing failure within minutes.
• Reduced Efficiency: Even partial air pockets dramatically reduce flow rate and pressure output.

When you work with a Well Pump manufacturer like Jingong Technology, we design every surface pump, booster pump, submersible pump, solar pump, and gas/diesel pump around the reality that proper priming = longer lifespan. This is why a trusted Well Pump manufacturer always includes detailed priming instructions in every operator manual.

Why Does a Well Pump Lose Prime? (High-Frequency Overseas Scenarios)

As an export-focused Well Pump manufacturer serving clients in North America, Europe, Australia, Africa, and Southeast Asia, we have catalogued the most common scenarios where overseas users lose prime:

1. New installation — the casing ships dry and must be filled before first start.
2. After maintenance or pipe replacement — the water column drains back into the source.
3. Power outage — check valves may weep, allowing slow drain-back.
4. Long-term shutdown — water gradually drains through minor leaks.
5. Air leaks in suction line — cracked fittings, loose joints, or failed gaskets.
6. Foot valve failure — water column collapses back into the well.
7. Low water level — drought or over-pumping drops the water table below the intake.
8. Filter or strainer clogging — restricts flow, introduces air vortices.

Any experienced Well Pump manufacturer will confirm: if you understand why prime is lost, you can prevent 90% of recurring failures. That is exactly the knowledge we are sharing in this guide.

What Happens If You Don’t Prime a Well Pump?

The consequences are severe and well-documented by every Well Pump manufacturer:

• The mechanical seal overheats and melts within 60–180 seconds
• The impeller suffers cavitation damage
• The motor windings burn out from excessive current draw
• The pressure switch cycles rapidly, shortening its lifespan
• In extreme cases, the entire pump head requires replacement

This is why Jingong Technology, as your dedicated Well Pump manufacturer, cannot emphasize enough: never start a pump that has lost prime.

Which Well Pumps Need Priming & Which Don’t — A Well Pump Manufacturer’s Breakdown

Not every pump needs manual priming. A knowledgeable Well Pump manufacturer will clearly distinguish between categories. Here is the definitive breakdown from Jingong Technology’s product engineering team:

Surface / Land Pumps — Always Require Priming

These are your standard jet pumps, centrifugal pumps, and garden boosters. Because they sit above the water source, they must pull water upward. A Well Pump manufacturer like Jingong always installs a foot valve at the bottom of the suction line — without it, water drains back into the source after shutdown, forcing you to re-prime every single start.

Critical rule from your Well Pump manufacturer: The realistic suction lift limit is 7–8 meters for water at sea level. Higher altitudes or hotter fluids reduce this limit drastically. Any leak on the suction side (threads, gaskets, cracked pipe) will suck air, not water.

Submersible Well Pumps — Usually Self-Priming

Since the entire assembly sits below the water surface, the casing remains flooded. However, a responsible Well Pump manufacturer will tell you that re-priming may be required:

• New Installation: Large-diameter (4″+) units may ship with dry casings. Always verify against the manual.
• Long-Term Shutdown: If disconnected from the discharge pipe for over 3 months.
• Low Water Levels: In shallow wells or ponds, the water level may drop below the intake, introducing air.
• Intake Clogging: A blocked strainer can cause a vortex that sucks air into the intake.

Jingong Pro Tip from your Well Pump manufacturer: On borehole units, ensure the foot valve (non-return valve) on the discharge line is functioning. If it fails, the water column drains back down, requiring a manual “re-fill” of the pipe from the surface — effectively a prime.

Solar Well Pumps — Strict Priming Required

Solar pumps are either submersible (down the well) or surface-mounted (at the wellhead). The surface-mount solar units present unique priming challenges that every Well Pump manufacturer must address:

The Soft-Start Factor: Unlike AC motors that jump to 50/60Hz instantly, DC controllers perform a “soft start” — ramping up voltage as sunlight intensifies. This means the impeller takes longer to reach full RPM, slowing down air evacuation.

Best Practice from Jingong Well Pump manufacturer: For initial commissioning, prime at midday when irradiance is highest (>800 W/m²). Alternatively, manually fill the casing and close the vent plug before exposing the panels to direct sunlight. Never allow a solar pump to run dry — DC motors can sustain damage even faster than AC units.

Gas & Diesel Powered Well Pumps — Dual Priming (Water Side + Fuel Side)

As an industrial Well Pump manufacturer, Jingong produces heavy-duty gas/diesel pumps for construction sites, agricultural drainage, and emergency flood control. These pumps require a two-stage priming process:

1. Water-side priming: Fill the pump casing completely with water before starting the engine (exactly like a standard centrifugal pump).
2. Fuel-side bleeding: For diesel engines, manually bleed air from the fuel filter and injection pump to prevent air-lock cavitation that can destroy the high-pressure pump. Gasoline engines use a primer bulb or choke to purge air from the carburetor.

A seasoned Well Pump manufacturer always warns: never run a diesel pump dry. Air in the fuel lines is the primary cause of start-up failure and can cause catastrophic engine seizure.

Common Causes of Lost Prime — Diagnosed by a Well Pump Manufacturer

When a pump “keeps losing prime,” a qualified Well Pump manufacturer looks for these root causes:

1. Failed Foot Valve or Check Valve

The foot valve at the bottom of the well prevents water from draining back. When it fails, the water column drops after the pump stops. This is the #1 cause of overnight prime loss reported to any Well Pump manufacturer.

2. Air Leaks in Suction Line

For jet pumps, any air leak in the suction line prevents the pump from creating the vacuum needed to lift water. Even a pinhole can prevent proper priming. A Well Pump manufacturer recommends using soapy water on all joints — if the foam gets sucked inward, you’ve found your leak.

3. Low Water Level / Dropped Water Table

Drought, over-pumping, or seasonal changes can drop the water level below the pump intake. A Well Pump manufacturer will advise either deepening the well or switching to a deeper-set submersible pump.

4. Cracked or Separated Drop Pipe

A crack allows air to enter and water to drain out. This primarily affects submersible installations but is equally relevant for deep-well jet pumps.

5. Worn Impeller

A worn impeller can’t create enough vacuum to pull water, especially on first start. A Well Pump manufacturer sees this most often in pumps that have run dry at least once.

6. Pressure Tank or Pressure Switch Failure

A waterlogged pressure tank (ruptured bladder) or miscalibrated pressure switch causes rapid cycling, which in turn accelerates prime loss. Your Well Pump manufacturer should be consulted for replacement specifications.

7. Solar-Specific: Low-Voltage Air Lock

Solar pumps are uniquely vulnerable to air lock during low-irradiance conditions (dawn, dusk, cloudy weather). A Well Pump manufacturer with solar expertise (like Jingong) designs controllers with anti-air-lock protection, but proper initial priming remains essential.

8. Gas/Diesel-Specific: Fuel System Air

If the fuel system has air, the engine won’t maintain consistent RPM, causing erratic impeller speed and intermittent prime loss. Bleeding the fuel system solves this — a detail only a specialized Well Pump manufacturer will mention.

Pre-Priming Preparation & Safety Rules

Safety is non-negotiable. Every responsible Well Pump manufacturer — Jingong included — mandates these preparation steps:

Electrical / Energy Isolation

• Electric pumps: Switch off the pump at the circuit breaker. Verify with a voltage tester.
• Solar pumps: Cover the solar panels or disconnect the PV input at the controller. DC voltage can arc and injure.
• Gas/diesel pumps: Turn the engine switch to OFF, set the fuel valve to OFF, and allow the engine to cool if recently run.

Pressure Relief

Open a nearby faucet or the pressure relief valve to bleed residual pressure from the system. A Well Pump manufacturer always reminds users: a pressurized system can spray water violently when the priming plug is removed.

Tools & Materials Checklist

Your Well Pump manufacturer also recommends inspecting the following before you begin:

• Suction line integrity (look for cracks, loose fittings)
• Foot valve condition (if accessible)
• Strainer / intake screen cleanliness
• Static water level in the well
• Pressure tank pre-charge (should be 2 PSI below pump cut-in pressure)

Step-by-Step: How to Prime a Well Pump (Universal 7-Step Method)

This procedure applies to most common non-submersible pumps — jet pumps, surface centrifugal pumps, self-priming pumps, solar surface pumps, and gas/diesel pumps. As a Well Pump manufacturer, Jingong Technology recommends following these exact steps:

Step 1: Turn Off All Power to the Pump

At your electrical panel, locate the circuit breaker dedicated to your pump and switch it to the OFF position. For solar pumps, cover the panels. For gas/diesel pumps, set the engine to OFF and close the fuel valve. This guarantees the motor cannot start accidentally. A Well Pump manufacturer cannot emphasize this enough: electrical shock is the #1 cause of injury during pump service.

Step 2: Locate and Open the Priming Port

Find the priming plug on the pump body (the “wet end”). It’s usually a square or hex-headed plug on top of the pump casing (volute). Turn the plug counter-clockwise with a wrench to remove it. If your pump has a pressure gauge port, some Well Pump manufacturer designs use that as the priming point — consult your manual.

Step 3: Fill the Pump with Water Slowly

Insert a funnel and slowly pour clean water into the priming port. Fill until water reaches the top of the opening and stays there. This may take 1–2 gallons; for deep-well jet pumps with long suction lines, the suction pipe may hold 5+ gallons.

Critical technique from your Well Pump manufacturer: Go slowly. Pouring too fast traps air pockets in the volute. Fill, wait for water to settle, then fill again. Keep adding water until it stays at the top of the port without dropping. This is the single most overlooked step — incomplete filling is the #1 reason a pump “won’t hold prime.”

Step 4: Replace the Priming Plug Securely

Remove the funnel and reinstall the plug. Wrap fresh Teflon tape on the threads if the old tape is damaged. Hand-tight plus a quarter turn with a wrench is sufficient. Do not overtighten — you can crack the housing. A Well Pump manufacturer sees cracked priming ports from overtightening constantly.

Step 5: Restore Power & Start the Pump

Restore electricity (uncover solar panels / open fuel valve and start engine). For solar pumps, expose panels to direct sunlight at peak irradiance. For gas/diesel pumps, follow the engine manufacturer’s starting procedure (primer bulb, choke, or glow plug depending on fuel type).

Step 6: Monitor Pressure & Flow

Watch the pressure gauge — you should see pressure start climbing within 15–30 seconds. Water may sputter and spit at first as air clears. This is normal. Open a faucet close to the pressure tank and observe. A Well Pump manufacturer confirms: steady pressure build-up + consistent flow = successful prime.

Step 7: If It Doesn’t Work, Repeat (But Don’t Run Dry)

If no water appears after 30 seconds, turn off the pump immediately — don’t let it run dry. Repeat the process, but this time let the water sit in the pump for 2–3 minutes before attempting to start. This gives water time to fill the impeller and volute completely. You can safely try 4–5 priming cycles.

Priming Guide by Pump Type — Exclusive Insights from a Well Pump Manufacturer

This section provides differentiated, category-specific priming procedures that only a full-line Well Pump manufacturer like Jingong Technology can offer. These insights go beyond generic tutorials and directly reflect our engineering knowledge across all four product families.

How to Prime a Surface Land Pump

Applicable products: Jingong surface well pumps, shallow well jet pumps, convertible jet pumps, centrifugal land pumps, garden boosters.

1. Turn off power at the breaker.
2. Locate the priming port on top of the volute (hex plug, typically 3/4″ or 1″).
3. Remove the plug and inspect — you should see the impeller. If bone dry, you’ll need more water.
4. Slowly fill with clean water until it overflows slightly. For long suction lines, you may need 5+ gallons.
5. Wrap the plug threads with fresh Teflon tape and reinstall securely.
6. Open a nearby faucet to relieve system pressure.
7. Restore power. The pump should build pressure within 15–30 seconds.
8. Once water flows steadily from the tap, close the faucet. The pump should reach cut-off pressure and shut off automatically.

Jingong Well Pump manufacturer tip: If your surface pump loses prime repeatedly, check the foot valve first. A failed foot valve is responsible for ~70% of recurring prime loss in jet pump systems. Our surface pump product line features reinforced foot valves specifically designed to eliminate this issue.

How to Prime / Re-Prime a Submersible Well Pump

Applicable products: Jingong submersible well pumps, 4″ and 6″ borehole pumps, deep well submersibles.

Standard submersible pumps do NOT require manual priming because they operate submerged. However, a Well Pump manufacturer must address these re-prime scenarios:

Scenario A: New Installation or Full System Drain

1. Ensure the pump is fully submerged and the foot valve is intact.
2. Fill the discharge pipe from the top using a funnel or hose adapter.
3. Pour water until the pipe is completely full — this may require 10+ gallons for deep installations.
4. Cap the top of the discharge pipe temporarily.
5. Restore power. The pump will push out any remaining air within seconds.

Scenario B: Air Lock After Long Shutdown

Even submersible pumps can develop air locks if the check valve is installed too close to the pump without a relief vent. Your Well Pump manufacturer (Jingong) installs a 1/8″ weep hole below the check valve on all our submersible units — this is the single most important “priming” feature for submersibles. If air becomes trapped, it escapes through the weep hole automatically.

Scenario C: Low Water Level / Intake Exposure

If the water table drops below the intake, the pump draws air. The only solution is to either deepen the well, lower the pump, or switch to a higher-suction-lift surface pump. A Well Pump manufacturer will always assess the static water level before recommending a solution.

Submersible Air Lock Fix — Troubleshooting Table

How to Prime a Solar Well Pump

Applicable products: Jingong solar well pumps (both surface-mounted and submersible DC variants).

For Surface-Mounted Solar Pumps:

1. Cover the solar panels or disconnect PV input at the controller.
2. Locate the priming port on the pump head.
3. Fill the casing SLOWLY with clean water until it overflows.
4. Reinstall the plug with fresh Teflon tape.
5. Critical: Time your startup for midday when irradiance exceeds 800 W/m². The DC controller’s soft-start means the impeller ramps up gradually — if you start at dawn or in heavy clouds, the pump may not reach sufficient RPM to evacuate air.
6. Uncover panels / reconnect PV input. The controller will soft-start; within 30–60 seconds, water should flow.

For Submersible Solar Pumps:

Follow the same procedure as standard submersibles — fill the discharge pipe from the top, cap temporarily, then expose panels to sunlight. Jingong, as your Well Pump manufacturer, programs all our solar controllers with anti-air-lock algorithms that prevent the pump from running dry even in low-light conditions.

Solar-Specific Considerations from Your Well Pump Manufacturer:

• Never prime at night or in heavy rain — insufficient voltage means insufficient RPM
• DC motors overheat faster than AC when dry — a solar pump can sustain permanent magnet damage in under 60 seconds of dry running
• Use the controller’s built-in dry-run protection — all Jingong solar pumps ship with this feature enabled
• Prevent overnight prime loss by ensuring the foot valve is functioning; if your solar pump loses prime overnight, the foot valve has failed and must be replaced

How to Prime a Gas or Diesel Powered Well Pump

Applicable products: Jingong gas & diesel pumps for construction, agriculture, and emergency applications.

These pumps require dual priming — water-side AND fuel-side. This is a nuance that only a specialized Well Pump manufacturer addresses:

Stage 1: Water-Side Priming (Same as Centrifugal Pumps)

1. Set engine switch to OFF, close fuel valve.
2. Locate the priming plug on the pump volute.
3. Fill the casing completely with clean water until overflow.
4. Reinstall plug with Teflon tape, torque to spec.

Stage 2: Fuel-Side Bleeding

For Gasoline Engines:

1. Open the fuel valve to the ON position.
2. Set the choke lever to START/CLOSED.
3. Depress the primer bulb 3–5 times until you feel resistance.
4. Pull the recoil cord or engage the electric starter.

For Diesel Engines:

1. Locate the manual lift pump on the engine block (small lever or knurled knob).
2. Loosen the bleed screw on top of the fuel filter housing.
3. Pump the manual lift pump repeatedly until bubble-free fuel emerges from the bleed point.
4. Tighten the bleed screw while maintaining pressure on the pump.
5. If the engine still won’t catch, “crack” the injector lines — slightly loosen the high-pressure lines at the engine head while cranking. Once fuel mists out, tighten immediately.

Jingong Well Pump Manufacturer Tips for Gas/Diesel Pumps:

• Always use fresh fuel — stale gasoline gums up carburetors
• For diesel, bleed the fuel system after every filter change or fuel tank refill from empty
• Run the engine at low idle for the first 30 seconds after water-side priming to ensure steady impeller speed before loading
• Our gas/diesel pump series features an integrated vacuum-assist primer that reduces manual water filling time by 60%

Common Priming Problems & Troubleshooting

Even after following the correct procedure, issues can arise. As an experienced Well Pump manufacturer, Jingong Technology has compiled the most frequent troubleshooting scenarios:

Problem 1: Pump Won’t Build Pressure After Priming

Likely cause: Air leak in suction line or failed foot valve.
Solution: Apply soapy water to all suction-side joints. If foam gets sucked inward, that’s your leak. Tighten or replace the fitting. If no visible leak, the foot valve has failed and must be replaced.

Problem 2: Water Sputters / Spits After Priming

Likely cause: Residual air pockets in the volute or suction line.
Solution: Open a faucet fully and let water run for 2–3 minutes to flush remaining air. If sputtering persists, repeat the priming process, filling even more slowly.

Problem 3: Pump Loses Prime Immediately After Shutdown

Likely cause: Failed foot valve or check valve failure.
Solution: The water column is draining back into the well. Replace the foot valve. A Well Pump manufacturer can supply OEM replacement valves — contact Jingong for your specific model.

Problem 4: Pump Runs But No Water Flow

Likely cause: Impeller damage from previous dry running, or incorrect rotation direction.
Solution: Disassemble the pump head and inspect the impeller. If damaged, replace. If rotation is reversed (common after electrical work), swap any two power leads. Consult your Well Pump manufacturer for impeller replacement parts.

Problem 5: Solar Pump Primes Successfully But Pressure Is Low

Likely cause: Low irradiance at time of priming, or undersized PV array.
Solution: Only prime at peak sunlight. If low pressure persists at midday, your PV array is undersized for the pump — consult your Well Pump manufacturer for proper array sizing.

Problem 6: Diesel Pump Starts Hard After Priming

Likely cause: Air remaining in fuel injection system.
Solution: Repeat the fuel bleeding procedure. Crack injector lines one at a time. If the problem persists, the fuel lift pump may have failed — contact your Well Pump manufacturer or engine service center.

Ultimate 6-Dimension Troubleshooting Checklist

When all else fails, your Well Pump manufacturer recommends checking these six dimensions systematically:

Pro Tips to Avoid Frequent Prime Loss

A truly expert Well Pump manufacturer doesn’t just tell you how to prime — we tell you how to NEVER have to prime again. Here are Jingong’s exclusive pro tips:

1. Upgrade Your Foot Valve

The foot valve is the single most critical component in maintaining prime. Jingong, as your Well Pump manufacturer, uses reinforced thermoplastic foot valves with stainless steel springs in all our surface pump packages. Cheap foot valves fail within 2–3 years; our OEM valves last 10+ years.

2. Install a Check Valve 10 ft Above the Foot Valve

This “double barrier” approach means even if the foot valve weeps, the check valve holds the water column. A Well Pump manufacturer with field experience knows this trick eliminates 95% of overnight prime loss.

3. Use Proper Suction Pipe Sizing

Undersized suction pipe increases velocity, which increases friction loss and the likelihood of air entrainment. Your Well Pump manufacturer specifies minimum pipe diameters for every pump model — never downsize.

4. Seal All Suction Joints with Teflon Tape + Pipe Dope

Double-sealing is standard practice for any professional Well Pump manufacturer installation. Teflon tape alone can shift; pipe dope alone can shrink. Together, they create an airtight seal.

5. Winterization for Cold Climates

In regions with freezing temperatures, drain the pump casing completely or use food-grade antifreeze (for non-potable systems). A Well Pump manufacturer serving global markets like Jingong always provides winterization guidelines in the manual.

6. Drought Protection

During drought, the water table drops. A proactive Well Pump manufacturer recommends installing a low-water cutoff switch (standard on all Jingong solar pumps) to prevent the pump from running dry when the intake is exposed.

7. Long-Term Shutdown Protocol

If you’re leaving a property for months:
– For surface pumps: drain the casing completely
– For submersibles: no action needed (they stay submerged)
– For solar pumps: disconnect PV input at the controller
– For gas/diesel pumps: drain the fuel system or add fuel stabilizer

Following these protocols — which only a comprehensive Well Pump manufacturer like Jingong can provide — extends pump lifespan by 5–10 years.

8. Original Manufacturer Maintenance Schedule

Jingong Technology, your dedicated Well Pump manufacturer, recommends:

• Monthly: Visual inspection of all accessible joints for moisture
• Quarterly: Pressure tank pre-charge check
• Annually: Foot valve inspection, strainer cleaning
• Every 3 Years: Full system pressure test for suction-side leaks
• Every 5 Years: Consider foot valve replacement as preventative maintenance

Frequently Asked Questions About Well Pump Priming

1. How often do you need to prime a well pump?

A properly installed self-priming pump with functional foot and check valves should only need priming once — at installation. If you find yourself priming more than once per season, there is an underlying issue (almost always a failed foot valve or suction-side air leak) that needs professional diagnosis from a qualified Well Pump manufacturer or well service technician.

2. Can you prime a well pump with running water?

Yes, you can use a garden hose connected to a municipal water source to fill the pump casing. However, if the well pump supplies potable water, you MUST use potable water for priming to avoid contaminating the system. Your Well Pump manufacturer always recommends using the same water source quality as your intended application.

3. Why is my solar well pump losing prime overnight?

The most common cause is a failed foot valve allowing the water column to drain back into the well while the pump is inactive. Since solar pumps only run when sunlight is available, the drain-back happens slowly over the night. A Well Pump manufacturer specializing in solar systems (like Jingong) designs redundant check valve systems to prevent this exact scenario.

4. Do I need to prime my submersible pump every time?

No. Submersible pumps are self-priming because they operate submerged. You only need to re-prime (i.e., refill the discharge pipe) after a full system drain, new installation, or if the water level drops below the intake. If you’re experiencing recurring prime loss with a submersible, consult your Well Pump manufacturer — the issue is likely a check valve or weep hole configuration problem, not a priming issue.

5. Is it bad to run a well pump without prime?

Yes, it is extremely damaging. Running a centrifugal or jet pump without prime causes the mechanical seal to overheat and melt within 60–180 seconds. The impeller suffers cavitation