Reasons for the decrease in the flow rate of the power pump

Reasons for the decrease in the flow rate of the power pump

1. General external issues (priority to check)

Leakage or blockage on the water intake side

The water intake filter and bottom valve are clogged with weeds, sand, plastic bags, resulting in insufficient water intake;

The water intake pipe is damaged, the connection is loose, or the sealing ring is aged, allowing air to enter the pump body, causing an air blockage and a sharp decrease in water output.

Treatment: Clean the filter and bottom valve, inspect, tighten, and replace the water intake pipe and sealing parts, and evacuate the air in the pipe.

Excessive suction height

The theoretical suction height of self-priming pumps is generally ≤ 8 meters. If the actual usage exceeds 6–7 meters, the pump will not be able to draw water or the flow rate will decrease, and the installation height can be reduced.

Problems with the water outlet pipeline

The water pipe is bent, flattened, or too long / there are too many elbows, and the water pressure is blocked, resulting in a decrease in flow rate; the water outlet valve is not fully opened, which also limits the flow rate.

Treatment: Straighten the water pipe, reduce the number of elbows, and fully open the water outlet valve.

2. Gasoline engine-driven pump (motorized water pump)

1. Insufficient engine power (commonly occurring issues)

The blower machine is faulty, and the engine cannot reach the required speed, resulting in a low flow rate for the pump:

Air filter clogged, spark plugs carbonized / aged, carburetor clogged, oil deteriorated, carbon deposits in the muffler, poor exhaust;

The accelerator pull wire is loose, the air intake valve is not fully opened, and the rated speed cannot be reached.

Treatment: Clean the air filter, replace with fresh fuel, inspect and replace the spark plugs, clean the carburetor, adjust the accelerator.

2. Pump body mechanical failure

Foreign objects entangled in the impeller: Water weeds, hemp ropes entangle the impeller, causing rotation resistance;

Impeller wear, blade damage: Long-term pumping water containing sand, the gap between the impeller increases, and the water pumping efficiency drops sharply;

Pump body sealing parts / mechanical seals damaged: Internal leakage, pressure relief;

Pump chamber contains air, self-priming fails: First use or after shutdown, the pump body is not filled with water, unable to normally self-priming.

Treatment: Remove the pump body to clean debris, replace the worn impeller / sealing parts, and add water before use.

3. Transmission component issues

The coupling or V-belt is loose / slipping, the engine rotates fast, but the pump speed cannot keep up;

Treatment: Tension the belt, check the tightness of the coupling.

3. Motor-driven pump (electric pump)

Voltage insufficient

Longer wiring, too thin wire diameter, high voltage drop during peak load, the motor rotates at a lower speed, the flow rate decreases, and the motor may overheat.

Motor failure

Capacitor decay (most common in single-phase pumps), bearing stuck, motor winding aging, the speed does not reach the rated value.

Same as above for the pump body

Foreign objects clogged in the impeller, wear, blockage in the inlet/outlet pipeline, leakage, insufficient water intake.

4. Common aging problems over long-term use

Water scale and sand deposits accumulate in the pump's internal volute and flow passage, reducing the cross-sectional area of the flow passage;

Excessive wear of internal gaps, severe internal reflux, continuous low flow rate of water output.

Treatment: Remove and clean the water scale and sand, replace the worn impeller / sealing parts directly if severely worn, add water before use.

Quick troubleshooting steps (in order, time-saving and efficient)

Check the water intake pipe, filter, and bottom valve, eliminate blockages, leakage, and bent pipes

Confirm the suction height, water outlet valve, and pipeline status

Motorized model: Check engine speed, air filter, fuel, spark plugs; Electric model: Measure voltage, check starting capacitor

Remove the pump body, clean the impeller entanglements, add water

If ineffective, check the impeller, sealing parts, belt / transmission structure