the engine was running fine until i put on a fuel/water separator filter. when taking it out today it started fine but seemed to be starving for fuel when trying to increase throttle. finally got it to run at full throttle but after stopping it did the same thing. got it running at full throttle again but i have noticed that the primer bulb doesn't get full/hard like it did before adding the fuel/water separator filter. i have tried to check for air leaks and everything seems fine. could there be air trapped somewhere even though i took it out for a good run? bad primer bulb? air in system? carb issues? i know it's not much to go on but would appreciate your thoughts... thanks...