Ripple is powered by a quirky one cylinder diesel engine (a Yanmar 1GM10) whose operating costs round to zero. At a liter an hour and an oil change once or twice a season, it just runs. For the first three years I had Ripple, I had no difficulties with it, and developed a fondness for its pockety-pockety rhythms. The last two years, however, I have had trouble starting, with symptoms that had all the earmarks of air in the fuel. Once started and warmed up, the engine ran like a top, but getting to that point was often challenging.
The problem was ameliorated somewhat by rebuilding the injector, which was 30% or more out of spec. The air-head diagnosis was reinforced by various minor faults discovered in the fuel system: a dodgy Racor filter head, loose banjos, looser-than-ideal fuel hoses. Most everything pointed in the same direction, and the mechanic I engaged helped get all of this stuff sorted, including rebuilding the injector, installing a more reliable Racor filter head (no prone-to-failure vent at the top), and a valve adjustment (long overdue).
The starting problem survived all this fussing. A pressure check on the fuel tank revealed no flow problems. Sourcing the fuel supply to an isolated tank did not solve the problem. Head scratching and consternation led to consultation with a higher authority. The culprit turned out to be the injector limiting component of the governor, which was badly out of adjustment.
I am happy to have had all the other components inspected, adjusted, rebuilt or replaced, but the essence of the problem that i've been struggling with for two years was the tension on a spring associated with the governor. Such a joy, to turn the key, and have the engine fire right up.