O.K. bought a nice straight shaft weedeater a couple of yrs. ago ran great next year it didn't couldn't adjust the carb. So went to the local shop to get parts they just kinda laughed that's too old to get parts!! Got online found whole carb for about $60.00, put it on no different, it idles fine go to give it the gas and it falls on it nose, took it over to a friend to help me and it ran just fine able to adjust the jet. Brought it home fired it up and it runs like $hit. Took it to a local saw shop and he thinks it is the I.C. unit??? would it run at all?? HELP
Sorry not a ChainSaw need help with Shindawa c25 brushcutter
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Sapo_feo
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If it runs and revs with the choke 1/2 on you probably have a leak in the crankcase. Either in the seam or the seals. If it still doesn't rev it could be the IC, but those things tend to last. I'd say your coil is on its last go 'round. Which one depends on the year. Mine is an '85 with coil 70000-71612. One other thing to check is the tank vent. Run about 1/3 tank of fuel with the cap loose and see what happens.
Rookie1
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You need to check the basics like vac test and Id say buy an inline spark tester to watch while running. Ignitions problems look just like fuel problems. Id say its the ignition if I had to gamble, but I dont gamble. 
I've got an old ECHO T-20 that fired weak. I removed and cleaned all of the ignition parts paying particular attention to the coil. I'm not sure If I had carbon tracking through the years of crud or if I corrected a loose ground connection. I reinstalled everything setting the magneto gap and got lucky. Runs like a Swiss watch again. Was I just lucky,,,, heck yah
nmurph
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Have you replaced the fuel line and filter? A hole in the line or a soft line that collapses will cause these symptoms. An air leak is going to give you an unstable, climbing idle and WOT. It could also be the tank vent but that is a very simple check (crack the fuel lid as mentioned above).
cambl
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New fuel line and filter, clean the fire screen, check the carb manifold gaskets, and then go through the carb if needed. Those carbs are very sensitive to high speed adustments, and a 1/4 turn either way on the H screw can make a big difference. The T25 ignitions last forever, and if the trigger unit goes bad you usually have no spark. Last time I had to get a carb kit I think there was an aftermarket one available.
Sapo_feo
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Coil is .830 ohms primary 5600 ohms secondary
Sapo_feo
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I don't remember any tests. That doesn't mean there aren't any, but if there are I've never done them.
Did you check if the the muffer is free? Over here (Japan) some kinds of wasps build nests in weedeater mufflers with round end pipes - seems to be just the right diameter.
Yep check the muffler for build up.
Well it is running. Took the carb off and checked all the gaskets and impulse passage. Reassembled and started it up and spayed W-D around the carb mount area no change. Check with choke half on and it ran like it was half on. Took muffler cover off and took the tailpipe with screen of and clean it like I did last year. This time I started it with the tailpipe off sounded like my old dirt bike but still didn't run any better so I REVED it up and all of a sudden it reved like it was suppose to. Must have been in between the exhaust port and muffler. Thanks Guys
