I have a 1/2 hp pump which I use to pump lake water to my irrigation system. The pump takes too long to turn on when the spicket is opened and sometimes too long to shut off when the water spicket is turned off. It has a pressure tank .

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

when pumping from a lake you will be pumping uphill
centrifugal pumps are susceptible to over loading because operators do not realize that water has mass and weighs a lot and the pump has to things to contend with
first lifting the water from the lake ( lift height)
the volume of water in the suction pipe will load the motor
now that it successfully lifts that water mas up it now has to push it up hill to a receiving tank of some sort
now distance to that tank ( friction in the pipe ) and height up to the tank inlet ( head pressure and it is measured as the height the discharge pipe is above the pump level --not ground level) have to be considered
unless you are a hydraulic engineer or have the equipment installed by irrigation experts all of this information will be foreign to you and that will result in too small a pump and yes it will overheat and in cases the water in the pump will boil as energy from the impeller of the pump has to go somewhere if the water is not moving
what I am suggesting here is to get pump experts involved to design a proper system with sufficient hp motor and pump volume to do the job

Hi Geralidine
Sounds like your pump is "air bound"...meaning that the impeller housing of the pump is full of air, and it cannot pump water.
Try bleeding the air out of the pump and put a positive pressure (garden hose pressure) and make sure that you shut the airbleed valve off after you start to pump.
Please take time to rate me
Bud

Sounds like you have an air leak. First check your fittings, next carefully run water over the pump seals (avoid getting water on the motor or you'll hurt yourself and the pump if not worse) the pump will prime if the leaking seal is covered with water. Take your time and be careful and it should only be a matter of a loose fitting or simple seal swap.

I used to take care of a system like that in the basement of a ten story college dorm. There was a big pump and a little pump. The purpose of the little pump is to maintain pressure when there is no usage of water. Then when a big demand comes, the big pump kicks in. I had problems with the
big pump getting hot, because the controls didn't work right. I unhooked all the controls and strapped a heat sensing aquastat box to the discharge pipe. When the water got hot, this state
would open a tiny little solinoid valve and dump enough water down the floor drain to keep the
pump cool.

If this is a self priming pump you will just have to fill the pot with water. If not you will have to open a valve and force some water through the system to prime the pump. This being done, if you still have no water you may have a suction leak keeping the pump from priming and may need a repairman at that point. Good luck.

pumps lose prime for a few reasons...bad foot/check valve, crack in the suction line are probably the two most common.. see if there is a threaded fitting( most pros put one on the pipe some where) on the top feed of the pump. open it up and add water til the pump fills up. if the pump is outside turn the pump on before resealing the fitting, otherwise resael the fitting and open a spicket outside. depending on your water table it could take some time to prime but in normal circumstances up to 20 minsif it does not prime you may want to consider hiring a pro!!

How big is your pump? How much HP rating? It could be a case of blocked water line. Just check your pipe lines and the gate valve for blockage. Just your e-mail
for your comments.

Your hose size is to small. Use a 2in black plastic line out to the lake. Inspect your foot valve, and
take your pump apart to see if you may have a pebble stuck in it, and remove the inner workings
and clean. Contaminates build up inside and need to be flushed out. Remember to replace the
gasket. Tighten all your hose clamps. Once your ready to start, spray shaving cream on your
fittings to see if your sucking air. I've been through it all and my pump works fine.

Chuck