That engine is on a run-a-way path.
1. Most common reason is out of the water and the idle set just 100 to 200 rpm too high. The confusing part to a 947 newby is that all other 2 stroke Sea doo engine models are set to 3000 rpm out of the water, but a 947 idles perfectly in the water when you set the idle speed at 27-2800 out of the water.
2. Allowing the head to get too hot becuasue it is running without water going through the motor when on the trailer.
3. And some of these next reasons could be a toss up in order, Replacing the carbs onto the engine for whatever reason and setting up the throttle cable adjustment too tight at the carb cable bracket, leaving the throttle plates slightly cracked open.
4. Clogged or partially clogged low speed jets.
5. Low speed adjusters are set too far in, not allowing enough fuel to pass at idle speed.
6. Water in the gas tank that ends up inside the carbs blocking fuel flow through the jets.
7. A poor job of keeping the carb base gaskets aligned when replacing the carbs onto the manifolds equals an air leak.
8. A pin hole or split in the plastic tubing that connects the engine case pressure fitting to the check valve in the rave valve pressure supply line, or a broken check valve in that same line. This allows air to go into the engine during up strokes, leaning out the mixture.
9. One stuck needle valve that will not open.
10. Rust inside the carbs, see #6.
11. A pin hole in the fuel pump pluse line.
