Water pump is not working . The part (black, square-like, with two contacts, looks like a relay) underneath the pump is the one that seems to be causing the problem. When I by-pass, the pump works. Also, if I need to get a new part, where can I buy one in Canada (vancouver) or over the internet. If it is that part in question that needs to be replaced, what is it called?! Thank you.

https://forums.edmunds.com/discussion/9784/hyundai/tucson/hyundai-tucson-acceleration-problems

here this will help. http://www.vadengmpp.com/owners-manual/chevrolet/1994-Chevrolet-Cavalier.pdf

If you look under the hood look to the driver side you will see a square black box it Gould the fuse box . Open it and see look for EFI relay . That controls the fuel pump and fuel injection system . Hope this will help you

It may be a stuck solenoid.
Under the hood, you should find a black box with a removeable top.
It will have lots of fuses of different colors and sizes.
Also there will be some little black cubes about one inch square.
If you flip the lid of th fuse box over, you should see a diagram of the stuff in there.
The little black cubes are solenoids. One will be the fuel pump solenoid.
Unplug it and look for burned contacts of a bad burned smell.
You may be able so take out another solenoid near it to test the one for the fuel pump.
Switch them out and try the engine.
If there is no change, then that is not the problem.
Just put everything back.
But it may very well expose a stuck solenoid. They are cheap at any auto parts store.

you did'nt specify what year,make,model of vehicle but will try anyway.fuel pump relays are usually found in the main engine fuse box under the hood.look for a black box either on driver or passenger side fenderwell of the car. open the box and look under the lid cover for fuse and relay locations.the relay should be a square black object about 2inches in size and simply plugs into the fuse box like a fuse.just pull upwards on the relay and it should just unplug,then install the new one in same place,just push it into the open fuel pump relay position.very simple to do. if you don't find a main fuse box,please repost your question with all the information on the vehicle as possible.thank you for choosing fixya.com

Underneath The Van On Drivers Side Just behind The Drivers Seat Is a Plug Square In shape It runs fuel Pump and Rear ABS....Gets Dirty And Looses Contact,Had The Same Problem But I had To Replace Plug All Together....

I have a 2004 kia optima 4cyl. found fule pump relay under the radio.
1)remove the crome square frame surrounding stick shift
2) pop out the cup-holder frame that goes around the stick shift
3) you will see 2 crews in front of stick shift. remove both
4) pop out frame that goes around radio (disconnect harness connector on side of this frame.
5) relay is a square looking box on right side below radio (approx 2"x2") has 2 screws to hold it in place.
BEFORE REMOVING: TEST IT BY TURNING IGNITION KEY(ONLY UNTIL PANEL LIGHTS ARE ON) YOU SHOULD BE ABLE TO HEAR or feel THE CONTACT CLICKING IN THE RELAY)

Sounds like the fuel pump failing,although it could be a lose relay on the fuse box normaly its a small black one, bosch small square box check the fuse box and relays make sure they are all down tight.

a relay is small electro magnet inside sometimes they stick or lose contact and cause intermitent faluts. worth a look wont cost you anything.

The fuel pump relay (square/silver looking part) is located right above the fuse box panel under the driver's side dash. Go under the driver's side and you will see two squares. It'll be the one that is higher up

Remove the backpanel of the machine, and look if there is water at the bottom of the machine. If so, use a towel or so to dry up the water. This should solve the prob.