Originally Posted by Brian Carlton

I'm in complete agreement with this. When you press the pedal down half way, the only thing the additional fuel does it to cool off the combustion chamber further. I have tried to start the 123 (previous vehicle) with no pedal and it appeared to almost catch. Then, when giving it pedal, it went right back to cranking with no firing.

My strong recommendation is to try and start marginal engines with no fuel for at least the first fifteen seconds. If it appears to begin to fire, just leave that key in the start position for another 15 seconds while the starter "helps" the engine to continue running. You won't hurt the starter this way and, after 15 seconds of combined running of several cylinders and the starter, the engine should run at idle, by itself. The timing of when to let go of the key requires some practice and patience.

Fortunately, I have not had to implement this procedure with either of these two because they have had no starting problems with good batteries and plugs.