Atomization is the issue. Diesel fuel does not atomize quite well out of a needle valve. On a truck engine the diesel is pumped at over 1000 PSI and atomized by the injector. Our engines don't have a fuel injection system, and can only let the fuel dribble in.

Ether is used to kick off the ignition. Without it the fuel has a tough time lighting up when it is in big droplets.