I've tried the following: •Compression test = Passed (160) •Pressure (leak) test = Passed •New NGK spark plug installed (BPMR7A) •Carburetor rebuilt with new gaskets and diaphram - cleaned w/ carb cleaner and compressed air •Carb needle valve inspected and arm adjusted correctly •Cylinder and piston removed for inspection & cleaning = Passed •New base cylinder and muffler gasket installed. •New Husqvarna hoses (fuel and pulse lines) installed •New fuel filter installed •Pulse liine tube (brass) inspected and determined to be clear •Carb intake manifold inspected = Passed •Flywheel removed to inspect key alignment (timing) = Passed •Fuel tank removed to check vent - appears to be clean and functional •New Husqvarna fuel tank cap installed •Fresh mixed fuel (50:1) added to tank •Inspected ignition module contacts and flywheel contacts - Passed •Determined spark / fire at spark plug = Passed •Saw has had minimal use and looks clean and new (well maintained) I removed the spark plug and added a small amount fuel into the cylinder, attempted to start (no choke). After several pulls the saw popped just once and did not run for a short interval, as one would expect.
I don't have a spark tester and will get this checked by a repair shop, but I'm more concerned with fuel delivery, as I remain suspicious about this being my problem. When I tip the saw on its side (fuel cap up) and remove the fuel line from the carb (not pulse line) no fuel comes out. If I then crack the fuel cap, fuel is immediately delivered through the line. Is this normal? Do I have a tank venting issue and if so how do I correct that? If this is normal and I'm certain that my carb is assembled correctly and my pulse line is okay, what might the fuel delivery problem be? I tried spraying WD40 into the carb and starting, but nothing (one pop). I'm lost to what the problem may be, or what to do next. I haven't been able to use my saw for two months, because I just can't seem to solve this problem. I'm open to any advice or suggestions that someone may have. Thank you.
Answer
Mr, Leavens.
We appreciate that you have taken the initiative to try and resolve the problem with your chainsaw, I think at this point the best option would be to locate a Husqvarna Service center who can verify your test results. It seems to me that you have gone above and beyond diagnosing your saw. It might help to have another set of eyes look upon it.
Thank you for using Answer Army.
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Ignition module was determined to have failed.
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spark testers are available from many sources for $5 or so. while troubleshooting, they can save time but are not really necessary.
if you remove the spark plug then re-connect the coilcap wire and allow the electrode to ground on the cylinder head while pulling the recoil start in a darkened room, you will clearly see if the magnets in the flywheel excite the ignition coil as they pass by TDC.
another confusing reason for a "no start" is the compression relief valve being stuck open. a tight top end that shows 160 psi should always be good to light the candle, but if that valve stays open, a Husqvarna will not have enough compressed air in the cylinder to ignite the mixture. plugging the jug, or manually closing the valve should answer that question in the long list of troubleshooting possible causes.
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you have a very good grip on how to troubleshoot. if you ever encounter a problem that may seem to stump you in the future, then send an email to . I am a professional mechanic that repairs/re-builds saws. I have developed a routine tailored to Husqvarna saws, and I am certain that together we would have your saw running right away, or accurately diagnosed to chase down the right part/parts...
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