you probably have your lines crossed. They should be routed like these in this picture. http://traxxas.com/products/nitro/ja...s-overhead.jpg
make sure you are not trying to start your engine backwards, you might not think you are, but if you unplugged the ez start you could have easly connected that backwards (red to black, etc) and that would spin the engine backwards.
That in combination with crossed lines could cause your problem.