Whisperflow 1.5 pump is drawing 1/4 volume of water.

possible impeller damage --seal /gasket --or motor not turning [rpm] up to speed

make sure to prime pump.
following that, be sure that there are no obstructions in the piping and that it can draw/push water freely

Close the supply valve to the tank. Open the priming port of the pump, (plug on the upper most part of the casing) pour in water until the pump is filled -up. Close the plug just finger tight. Run the pump. slightly open the plug just to bleed the air with little water. If all water is coming out, the pump motor should cut-off indicating the pump is already primed. Gradually open the supply valve. Pump motor will restart again.

Hi Bert Man...

You problem is the "foot valve" at the bottom of the well is worn or has some dirt/debris in the sealing face and allowing the water to flow back into the well overnight when the pump is not keeping the pump and well pipe full of water. They are non replaceable being they are at the bottom of the well, hence the name "foot valve".
You can correct that problem by the addition of a check valve above ground installed in the suction pipe of the pump, be sure it is a spring loaded device so that you can install it in any position..
Another way to keep the pump primed is to feed a small amount of pressurized water into the pump all night, you can do this by the addition of a connection to where the pressure gauge connects to the pump.
Please take time to rate me

If you are trying to draw water from a lower place, you may have lost prime. It is also possible there is a reason for this loss of prime, maybe a leak on the suction piping. Remove some fitting on or near the discharge of the pump, fill the body completely with water. If it goes in, fill the entire suction piping with water, too. Open a faucet nearby, turn on the pump and wait up to 5 minutes. It should spit and sputter, sound will change, some water will discharge, but eventually, you should get steady flow.
If you lose prime again, look for leaks in the suction piping from the inlet of the pump to where the piping goes into the ground.

Your FixYa Texpert,
Gary

Has your pump lost prime? If so prime it. Never run a pump dry.
Is your impeller turning? Is the impeller worn out? Check these things first. Also, make sure the intake to the pump and all the piping to the pump are clear and not clogged.

If you ran the pump dry, it probably needs to be primed again. Make sure that you bleed the air from the line and get a good prime. In a worse scenario, it is possible that you burned up the motor in your pool pump. If this is the case, you will likely have to replace the entire filter and pump system.

ITS GOING TO NEED SERVICE. LOOK FOR YOUR LOCAL POOL PUMP MOTOR REPAIR GUY, USE YOUR ZIP IN YOUR SEARCH

Is the pump leaking water? If you lost the prime or are having trouble priming then there would be an air leak somewhere on the suction side of the pump. Poor suction would interfere with the sweep. One way to ell if the pump or suction line(s) are leaking is to examine the inlet basket once the pump is primed. Any air left in there after a few minutes of operation once primed would indicate a leak in the suction/pump.

Your pump is overheating. Check the current draw of your pump during operation. The amperage should not go above its current rating.
Remember Power (Watts)= Voltage (VAC) x Current (Amps). For a 100 Watt motor running at 120 VAC then the current I should see is approximately, 1.2 Amps. If I see 2 amps draw on the motor then I now its about to burn up or another problem has occurred. Values higher then 1.5 times the nominal operating current shows problems with motor or motor operation (excessive load, bad bearings, exc.)
Make sure that the pump is fully primed during entire operation. Note: Pumps hate cavitation and dry run times!
If all of the above is ok, then you may need to increase the capacity of your pump or place two of the same pumps in series for the extra head pressure.