I have a 1999 Cub with a single cylinder Kohler Courage engine. This engine has always started hard since it was new. I need help with ideas on what could be wrong. Here are the symptoms:
- When cold, the engine must be cranked over and over a half-minute or more. When cranking, nothing happens, then it finally starts as though nothing was wrong - a little choke stumbling, but same as if it had fired up right away.
- Once started it runs well at speed, power and idle - no misfiring, stuttering or anything - just a good-running engine.
- It always starts...eventually. If the battery is weak, jumping or charging it will crank the engine normally...forever.
- When warm it starts on the first key turn and runs easily.
- air and fuel filters clean.
- It has a manual choke that closes properly and completely, and a throttle that works properly.
- I thought the valves were out of adjustment. I have adjusted them several times and this works for about one cold start cycle and then it's the same thing. Last time I used red loctite on the adjuster screws. no change.
- these have a crankcase-vacuum-operated fuel pump, but it seems the engine would have problems even after it starts if that was defective??
- the fuel tank is under the seat, so it's not gravity fed.
- It has several safety interlocks, but these should not allow it to start at all, right? There is an oil sentry switch.
- It never acts flooded. When it does start, the choke will flood it if I don't pay attention - a perfectly normal condition.
Any thoughts about what to do or where to look?
Give it a little shot of starting fluid into carb next time.If it fires right up the choke is not fully closing or the butterfly is not closed off enough.
I have seen many single courages that needed the purple coated screw turned in a few turns to push choke closed tighter.
If not then I would suspect fuel pump losing prime BUT in less than a week the carb should still be full of fuel and start normally and the fast speed and vacuum pulses would put fuel to carb quickly. I have seen fuel pump issues that would fire right up and only run for 15 seconds and then carb bowl runs low and hasn't sucked fuel from tank yet.
I have had several with plugged or restricted lines or gas tank outlet nipples.
Take line off at fuel filter and you should be able to suck fuel easily out of line by mouth. Half the time it runs our even though not gravity design.
I have blown grass, sticks, lady bugs, japanese beetles out of lines in last 2 years alone.
Old cracked slightly air leaking lines to fuel pump will cause it to lose prime after sitting.