Homelite ST-175 won’t start

[toysmaker]

Hi, I have a homelite ST-175 String Trimmer that I haven’t use for a couple years. Because of that I went through the carb, replaced fuel filter and lines, checked compression, 100 lbs, checked for spark, good spark, pulled the muffler and cleaned the inside of it. While the carb and muffler were off I checked the piston and cylinder for damage and both looked good. I cannot get this string trimmer to start/run even with starting fluid. What am I missing? Any ideas? Please help.

[twostroke]

It sounds like you went through everything that wouldn't make it run. It sounds like you're not getting spark, but you said that you have good spark. There a few things I can think of. The first thing is that you're getting an intake/vacuum leak at either the base gasket or the little 4-bolt black crankcase cover. I do know that on those smaller Homelite blower and trimmer engines that you have to remove that crankcase cover to get the fuel tank off, and if you changed the fuel lines and filter you must have removed the fuel tank. If you did, ensure that the gasket looks okay. I had an old McCulloch 1-10 that would not start at all, cleaned points, rebuilt carb, new fuel line and filter, and nothing. It would barely even fire off of gas sprayed in the cylinder. Tore it apart and the crank seals were shot and the crankcase sealant was completely gone. It might be your crank seals or like I said, a base gasket or the crankcase cover gasket. Another thing is that you're not getting crankcase pulse (via a leak) to run the fuel pump diaphragm, and you can check that by pulling the carb and feeling a "pulse" of air from the little pulse hole on the insulator block when cranking over the engine. Another thing, get some premix gas in a little bottle or something and spray a tiny bit into the combustion chamber, reinstall the plug and see if it fires. Ether is sometimes not enough and you don't want to use ether anyway on a two-stroke because it has no lubrication. Hope this helps.