Yep. You will need to pinch the hose that goes from the pump to the exhaust. If not, it can fill the exhaust with water and then it will fill the engine.
Look up your Owners Manual. Find the hose that connects to the exhaust manifold and work your way aft and find a spot to pinch off the hose. Some people have install a 1" plastic ballvalve with 3/4 hose barbed connectors to 1" pipe thread.
The gray PVC will work, just keep away from heat as far as possible. The 1" is important so the inside diameter is not smaller than the hose or fittings. Don't restrict the water flow. The hose is 3/4.