The engine starts very hard after sitting over night I seem to think it is not getting fuel, the fuel pump sounds like it is working very hard and its loud. Once I get it going it runs very well at low speeds (0-50 miles/hour). If i try to driver faster than 55 miles an hour one cylinder will start to miss and finaly shut down, (the left cyl only). If I stop and let it idle for less than a min the cyl will catch again and the engine runs very well again (under 50 miles/hour). This is driving me crazy can anyone point me in the right direction to correct this fault. Engine compression is 140 PSI in both cylinders. I fix cars for a living however I don't know much about sleds.