The good thing about gas engines is their simplicity. It only takes 3 things to make them run, but if even one is missing, no go.

1. FUEL: Check your entire fuel plumbing system. Kinks and clogs can be difficult to notice, so inspect very carefully. The first place I always check is the clunk. I had a piece of plastic (where did that come from?) stuck in my clunk, blocking the fuel from drawing into the fuel line. Cleaned the clunk and installed a filter inside the tank, problem solved. Now, I always use a filter inside the tank, and one in the fuel line just before the carb. Next, reset the carb needles to the original factory specs so you'll be sure to be getting adequate fuel to the carb. Check the carb's diaphragm, too. A rip or hole in it will keep it from pumping fuel, so inspect it closely as well. When inspection is complete, go to step 2.

2. SPARK: Take the plug out of the cylinder head and closely inspect it. Is it covered with gunk? Is the gap ok and clean, or does it need cleaning and/or adjustment? Did you short it out and turn the motor over to see if it produces a spark? Since your engine runs for a few seconds, this is probably not your problem. It never hurts to check, though.

3. AIR: I had an old Walbro carb on a Quadra 35 that had a loose butterfly valve. The shaft would turn, but the small disc on it would not move. I had lost a set-screw out of it, due to vibration I suppose, and it never opened up to let any air in, effectively choking the engine to death. Check to make your carb is working correctly.


Finally, make sure you're using a good starting procedure. Here's what I do...

I stick my finger in the throat of the carb, and with the kill switch in the KILL position, rock the prop back and forth against compression until my finger is wet. Flip the kill switch to the RUN position, 2 clicks of throttle, and flip the prop. Should start nearly every time. If you don't get a burp, start over. REMEMBER THE KILL SWITCH!!! Don't want you to take off a finger or worse.

Hope this helps, it has worked for me for years.