Small two-stroke engine runs poor

Question

I have a borrowed cultivator (Echo TC-2100), and having hard time running it. It looks fairly new, and in good condition, but was possibly poorly stored and was not winterized.

At first I could not start it at all. I checked the spark, and it was weak, and, moreover, the plug porcelain jacked was cracked and ignition was shorting a bit (I was feeling it while touching the cable even in heavy leather gloves). I replaced it, the spark was sort of weak still (even in comparison to other small engines), but I was able to get it to start (not sure that could be the issue still).

Now I got it to the point where I can start it every time with choke on, but it would not hold the idle on choke for long, and otherwise, as soon as I drop the choke it dies, sometimes trying to stay alive. It would not idle, and would struggle and die if I try to throttle it.

This is emission-restricted model, so the carb adjustments are limited with plastic caps, and I had adjusted them as per manual (PDF). Other issues I see are a) primer bulb cracked and seem to leak air (how much of an impact would it do?), b) fuel filter can be clogged, and c) carb main jets could be clogged. I would like to understand the symptoms better, and find the cause before I start putting money into replacing parts for the unit that is not mine.

Answer 1

Your problem is lack of fuel, so carb is at fault. Your diagnostic thinking is on track, it would seem. Per your questions:

a) Try and put a small piece of Duct Tape over the crack in the primer bulb and see if that helps. If the carb is drawing air through there, it will not be pulling gas as it should, which will bring about the "choke only" run situation you are describing. If this fixes it, just let it run as you need, then show it to your friend when you return it. Seems it was that way when you got it, to me. Never underestimate the power of Duct Tape ;-) It seals things quite well.

b) Is there even a fuel filter? Most small engines I have or have run, do not as far as I know. Has never been the issue, anyway.

c) This seems most likely. On small engine carbs and ethanol enhanced fuels, I find this usually is the culprit. Using Stabil or other fuel stabilizers helps tremendously, especially if it's sitting over the winter months. If you don't, clogged carb passages ensue. With the newer carbs, which don't allow for adjustment, I have found it very difficult to successfully rebuild these carbs. It is much easier on time/money/aggravation to just replace it, as the carb is usually not all that expensive if researched through the internet.