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Motor pump, operating incidents

The causes of failure of a motor pump can come either from the suction system by defusing (the closure of the strainer is the most frequent case), the discharge system, the engine block, or the pump body ( locking of the fins). Various appropriate checks can quickly locate the cause of the failure.

The failures of a motor pump can originate from:

  • the pump motor,
  • the pump itself,
  • the upstream line (draw-suction),
  • the downstream line (distribution).

Some devices include an alarm device, visual and / or auditory, which is triggered automatically in case of untimely shutdown of the pump. There are also safety cut off the engine in case of defusing the pump, to avoid running idle and overheat. This is mainly the case for water distribution systems by pressure tank; these also include a safety switch that cuts the motor when the maximum operating pressure is reached and resets it when the pressure falls below a minimum threshold.
These tanks are always equipped with a safety valve that opens before the pressure reaches the tank resistance limit.
It is recommended to periodically check (approximately once a year) the safety devices. For complete installations of individual distribution of pressurized water, it is wise to have a complete control by a specialist at least once every two years.


The main incident that may occur on the upstream line and interrupting the pumping is theshutter strainer. Dead leaf clumps, branches and aquatic weeds are the most common causes, in the case of well sampling. To counter it, it is recommended toexamine the well from time to time and close its opening with a slab or slab. This will be the first security. Attach a flashlight to the end of a rope and lower it into the well near the surface of the water. If you find grass, leaves, etc., remove them with a long-handled dip net.
It is not always easy to go down to a well. If you must do this, take maximum precautions and never do this work without making sure that someone is available to help you when needed.
Ask him to "make sure" by holding the end of a solid string that you will pass the other end under your armpits (two to three turns, closed by a key node). The laying of a suction piping sliding or made of semi-rigid plastic, allows to go up the strainer on the surface of the well to clean it.

Control of compressions and inspection of the blades of the motor pump

Control of compressions and inspection of the blades of the motor pump

The pump

The defusing pump can come from a leak in the suction pipe, venting of the strainer (insufficient drawdown level) or leakage of the pump itself. Some pumps have, at the upper part of the body, a plug allowing the reintroduction by pouring water using a watering can without its apple. If this operation does not prevent frequent defusing, locate the leak and fix it.
Most often, it is the gland seal of the drive shaft that is involved: it causes a significant flow of water between pump and motor. Excessive wear of the vane or vane of the pump volute under the effect of the passage of abrasive sand in the pump, also leads to defusing. This phenomenon is then preceded by a decrease in flow and pressure.


Engine failures can be detected quickly if the pump is no longer running. Check first that the pump is not blocked by detritus or objects, or that the tree is not seized. If the motor is connected to the pump by a flange coupling, disconnect and try to turn the pump by hand.
On a heat engine, first check the fuel level, then the ignition and, if these checks have no result, check the carburetion by removing the carburetor if necessary.
On an electric motor, check the coals (in case of universal motor) as well as the power supply. Make sure that the safety relay has not tripped.

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