2 Stroke engine repair can be accomplished once the severity of the problem or damage is assesed. As with all engines, they require two basic things to operate. First all engines require fuel. There are a few ways to check if the engine is getting fuel. Remove the spark plug and see if they are wet. If the spark plug is not wet, you can remove the float bowl to see if fuel is being delivered to it. If there is no fuel you can check the needle and seat of the carburetor, or the fuel pump. You can generally repair a sticking needle simply by moving the needle manually. If the 2 stroke engine is fuel injected you will need a fuel pressure gauge and will then need to attach it to the fuel rail. Check that the specified pressure is being reached. If not, the fuel pump is probably faulty. The next important thing to check is that the engine is producing spark.
Snowmobile engines are generally two strokes except for a few new four strokes. Repair and troubleshooting is similar to any other vehicle. First you want to identify if it is a fuel or ignition problem. Remove the spark plugs and look to see if they are wet or dry. Do they both look the same or are they different? If different then one cylinder’s carb or ignition may have a problem. A wet spark plug could be many things. Take the spark plugs, dry them off with a clean rag and place them back into the plug wire. Lay the spark plugs on a metal part of the engine and spin the engine(try to start) Look at the plug gap as you spin the engine over, do they all spark descent? If some of the sparks look weak you could have an ignition problem. Hopefully the plug is fouled out and just needs to be replaced, try that first. If weak spark remains, check that the ground wire for the ignition coil or system is good. Worst case you could have a bad charging coil or bad wires shorting out somewhere.