Any thoughts on what would make my L2050 not start without activating the glow plugs for about 45 seconds? If it is turned off for more than 60 seconds I have to activate the glow plugs to get it to start, even in 100 degree weather? Compression, valves, injector pump, injectors? Not sure where to start. It does blow some black smoke when it first cranks, then after a minute it runs great. Thanks!