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mustangm

Echo SRM-1501 string trimmer not starting

mustangm
12 years ago

This is the first time in 15 years that I have not been able to get this started. Given its age, I decided to replace the carb gaskets, fuel line, fuel filter and spark plug. It has a Zama 2 cycle carb. The old gaskets were very stiff, and replacement was very easy. After refueling with fresh fuel, I primed, choked it and gave it a pull. On the second pull it popped. I took the choke off and pulled and pulled and pulled. Tried choking it again, but nothing. Just that one pop.

I tested the spark plug in the dark and it fires bright blue. I tested compression: 90 psi after 2 pulls (I think this is ok). And I believe fuel is making it into the engine. After 3-4 pulls I look down the carb and can see wet fuel. I took the plug out and pulled several times. I am not sure if fuel is making it to the combustion chamber as the plug does not seem wet. I removed the muffler and do not see an over-abundance of carbon - seems normal. I also took the carb off again and the piece between the carb and the engine. I pulled the cord until the piston was at the top. At this point I could see under the piston and it was very wet. I tipped the trimmer and quite a bit of fuel poured out.

Any ideas what is going on? Thanks as always for the help.

Comments (5)

  • ls3c6
    12 years ago

    try starting without priming it after it dries out, I just rebuilt the carb on my srm-260 and found that priming even one push floods it. Starts on 1-2 pulls after sitting for a few days without priming.

  • mustangm
    Original Author
    12 years ago

    Well I finally got it started, and honestly, I am not exactly sure what the original issue was. I will explain what I did and maybe someone can tell me why it is running ok now. First, I tried the suggestion by ls3c6 (Thanks!) but it still did not run. I read somewhere that the compression of a 2-cycle needs to be in thr 150 psi range. Since my compression test showed 90, I decided to tear it dowm. I removed the carb, muffler, fuel tank, etc. I then removed the 2 hex bolts that secure the head. Here are a few pics before I cleaned it up.

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    {{gwi:130603}}

    I was able to see the passages where the fuel/air mixture gets from intake to the head. These were not clogged and looked fine. I cleaned up as much carbon as I could. I then used a scroll of gasket material and recut a new head gasket and also a new intake gasket. I kept the same exhaust gaskets and the same gasket between the carb and the plastic air horn (part between the carb and engine.) I put it all back together, choked, pulled. It popped first pull. Took off choke, pulled, and WOW!. It actually sounds so much better, quieter than it was the past 10 years. My only concern is that there was some smoke coming from the exhaust. I am not sure if this is residual burnoff or something else. I will run it longer today and see. Also, out of curiosity I redid my compression test. It still tests 90 psi. So I am stumped. I have no idea what the root cause of the issue was. If the issue was related to airflow thru bad gaskets, then I would have expected a higher psi reading. Any ideas?

    As always, Thank You for your advise, criticism, etc...

    Mark

  • ewalk
    12 years ago

    Must: The compression test should be done with a light coating of oil or premix sprayed within the cylinder to seal the rings . Usually 4-5 full pulls are required for an accurate compression measurement . I would think you may seee a increase within your recorded compression readings accordingly . The piston and head do show a little carbon build up but not excessive more or less routine for a unit that has not seen a lot of fuel treatment usage or preimium oil use . Verify your comp. reading and start using a fuel treatment such as Lucas or Star*tron or Sea-Foam etc. Also 50-1 fuel ratio with Premium oil such as Echo or Amsoil Sabre will keep your unit running well for yrs . Let us know how you make out .

  • mustangm
    Original Author
    12 years ago

    Well Walt, I poured about 2 teaspoons of 2-cycle oil into the spark plug hole, swished it around a bit, installed the compression tester, and in 5 pulls it read 150 psi. Thanks for the compression testing tip and the other great info. :)

  • ewalk
    12 years ago

    No Problem Mustangm Happy Trimmimg ! P.S. The residual smoking will most likely go away , you have a Great Echo Model !