During cold weather and using a small battery, it is very important that the engine starts on the first or second time over. A primer can be a big help in starting a very cold engine.

Since I must go to the propeller end of the engine to remove starter and ignition system safety devices, I wanted to be able to prime the engine at the same time. Also, as the FireFly is close to the weight limit, it was important to minimize system weight.

I started with a primer pump from a discarded weed wacker engine carburetor. This pump is mounted onto the side and draws gasoline directly from the Bing float bowl. The fuel is pumped through a small tube, and up through an open stop cock valve that is attached to the Bing primer port. This valve is closed after priming to prevent additional fuel flow after engine start up. Before one starts the engine, the fuel removed from the carburetor bowl is replenished with the fuel system squeeze bulb.

Before engine start and removing the FireFly from the hangar, I open the valve, squeeze the primer bulb two or three times depending on outside temperature, close the valve, and by hand pull the engine through two compressions followed by rotating the propeller backwards to bring the piston up against compression. This lets the starter get a run before for the crank comes up on compression. By doing all of this before removing the FireFly from the hangar, the fuel is well voliatized in the case. After donning my flying gear and getting into the cockpit, the enrichment jet is opened and the throttle is closed. Upon engaging the starter the engine starts on the first or second turn.