String Trimmer Won't Pull or Start

I’ve had a Troy-Bilt 2-cycle string trimmer model TB75SS for a little over two years (just past the warranty…). Recently I was using it when the engine cut out. On trying to restart it, the pull start was much more difficult to pull and I couldn’t get it going.

After doing all of the normal maintenance checking, I brought it in for repair and was told that the “ignition coil (?), starter rope, air filter and spark plug” needed to be replaced for a total of $100. Not only is this almost the price of a new one, but I didn’t think that was the problem to begin with, so I didn’t have it serviced.

I now have it partially taken apart. I’ve noticed that with the spark plug out, the pull start is easy to pull and the cylinder moves fine. It’s only with the spark plug in or when I’m blocking the plug hole does it become extremely difficult to pull. I have the muffler off, so it isn’t that or the spark arrest screen being clogged. I’ve also tried cleaning inside the cylinder with carb cleaner and soaking it briefly with oil, all with no luck.

Any ideas or help would be greatly appreciated…

 

so you've made sure the exhaust port was clear? your right about not needing that stuff...... they were trying to get your money for mostly unneeded stuff. starter rope ain't broken, they're not sure the plugs fouled or the ignition coils bad (most likely not) and the air filter needs replacing, more then likely foam, and its owner replaceable, cleaned and oiled by the owner.

 

Just a stab in the dim here________
How about this:
You are use to how the machine feels when pulling it over, and having the ignition of the fuel help spin it over, and now if the ignition is failed, you feel more resistance from the machine?
I would first check for spark.
If I had a friend with a trimmer, then I would ask to pull theirs over with the spark plug disconnected to be able to get a feel for the machine with no spark.
If it is "stiffer" then other machines then I would wonder if the mach..............
Look for spark first.

 

Thanks to you both for the responses. Turns out that I'm not getting a spark after all, even with a new spark plug. It looks like it's part #753-04336 ("module assembly" in the manual) that is the culprit. It's about $40 online, so hopefully I'll be able to fix this myself for about half the cost.

To answer your question, it is definitely much more difficult to pull than before. It's amazing that the spark can make such a difference just with pulling the rope. Thanks again for the help.

 

Did you make sure the spark plug was grounded when checking for spark?