Fixing A Stihl Trimmer That Won't Start

I was given this trimmer to fix and to be quite honest I really enjoy working on these but it surprises me when I had to fix these I figured for all the money you spend on these trimmers that they would never have any issues ever either way I just chalk it up to poor storage practices and that's pretty much about it but you still have to wonder just how much it's going to cost to fix it mainly because it's an extremely expensive brand unfortunately by the end of this video you may not like what I end up doing in today's video we're going to look at this steel string trimmer and the problem is that it won't start and run now this thing belongs to a co-worker of mine at the massive facility I work at and they must be making a lot more money than I am we've both been working there for the same amount of time and somehow they're able to buy good machines like this one and I'm stuck using a feather light now I'm going to try and repair this string trimmer but yours might be a little different so this might not work on yours so if things are not working out for you like in the video please ask about it I'll be glad to answer your questions foreign as you can see it won't do anything when pulling on the rope now in the last video where we give it an extensive cleaning it did start and run after putting some fuel into the carb's throat what that tells me is that the engine and ignition system are both in working condition but the carb or the fuel in the tank is the issue that's keeping it from starting the first thing I want to do is to pour out the fuel that's in the tank now this fuel should be the fuel that the owner is mixing and using on most of their two-stroke equipment I want to see if it's stale or if it has any water in it now my first impression is that I don't like the color of this oil only because it makes it harder to tell if the gasoline is old but after smelling it and looking at it in the jar I don't think it's stale and there's no water in it either so I don't think the fuel is the issue unfortunately that means we have a lot of work on our hands now after looking inside the fuel tank I can see that there's a steel branded fuel filter inside the tank which is great news if you recall a few videos back the aftermarket filters don't seem to fit the fuel lines very well and can cause some issues with the fuel while I have the cover off the engine I also want to remove and inspect the spark arrester screen now over time depending upon how the trimmer is used the engine can cause an excessive amount of carbon to be expelled and the screen will sometimes get clogged and cause some terrible issues now from the part I can see before taking it out of the muffler it appears that it might be clogged with carbon but after getting it free from the muffler you can see that it's not clogged but it does have quite a bit of carbon starting to collect on it now even though it's not an issue right at the moment it could be an issue later on this season so this will be a great time to clean it now there are many different ways to clean the screen but I prefer to use a torch you can use a Grille or even just a fire to do the same thing if you don't want to use a torch you could always try bathing the screen in carb cleaner or maybe even oven cleaner like I said there's more than one way to do this job so don't get hung up using a torch after burning the carbon I'll then use a wire brush to remove the Ash and then reinstall it back into the muffler now you don't have to reinstall it and run the trimmer without a screen but the screen is there to prevent grass fires so I'd recommend reinstalling it now since this engine has valves like a four cycle engine I want to check the valve latch or basically the clearance between the top of the valve stem and the rocker arms if the clearance is out of Tolerance then you might have starting and even running issues now for this part we'll need to put the engine on top dead center or basically when the Piston is at the top of its stroke right after the intake valve is opened and closed now there is an alternative to putting the engine to top dead center or TDC and that's to rotate the engine until one of the valves is fully open at which point you would check the clearance on the other valve however I would use whichever method works best for you now to check the clearance you'll need to cut a four thousandths of an inch shim to fit in the opening if it's too loose you can tighten the nut on top of the valve and of course loosen it if it's too tight now the shim should just drag in The Space Between The Rocker and the valve stem and after checking this one it turns out it's exactly where it needs to be and the shim just slides through the Gap with some resistance after that I'll then replace the valve cover and the bolt and then move on to the spark plug now normally I wouldn't care too much about it but since it looks to be a bit oily I'm going to burn off the oil before reinstalling it yet again there are probably other ways to clean the spark plug such as using carb cleaner but fire seems to work the best for me after I'm done turning the oil into Ash I'll then use the brush again now I don't expect it to look brand new but I do expect it to have a lot less Carbon on it now while I'm here I'm also going to check the gap on the plug as well and we're looking for something close to 20 thousandths of an inch now this one is about 21 thousands which is pretty close so I'm not going to change it but if you want to you are more than welcome to give it a few Taps to close the gap up the next item and the most important one is to of course get the carb off the engine for an inspection and this is when things get very interesting and also very disappointing now this carb is is not the most advanced one they've ever made but it does its job very well at least this one still has fuel adjustment screws which on some of the newer ones are sadly missing now this one kind of put up a fight but after a bit of persuasion it probably came loose and now comes the fun part now this carb isn't too special except for the large port at the bottom of the car which is for the impulse line that helps to work the pump inside the carb if this part of the carb does not work then it's very unlikely the engine is going to start and run after removing the pumping section of the carb we can see the main body of the carb one of the most important parts is the round opening where the inlet screen is located at if this screen is clogged with debris then the car will not be able to deliver fuel to the engine however this one looks to be clear which is great news the next part we need to inspect is this diaphragm we want to see if the check valve flaps are parallel with the rest of the diaphragm which it is that means we can reuse it however this next part is the part you may not like so on this type of carb the impulse line helps to work the pumping section and it has its own spring-loaded diaphragm in it that means we need to get it out and see what kind of condition the diaphragm is in now I'm not an expert in this area so please don't jump on me all at once but this diaphragm seems to be much too stiff to work the way that it should that was made pretty clear at least in my mind but the test starts we tried earlier where the engine didn't even try and start as you can see the diaphragm is very petrified so much so that it will stay in whatever position you put it in now I could try and rejuvenate it with my solution however I want to see what kind of condition the metering diaphragm is in first if it's just as bad as the pumping diaphragm I'm going to do something that most will not agree with and that's to order an aftermarket carb of course the reason why most are against this idea is because the aftermarket carbs are seen as low quality in comparison to an oem carb so why even bother choosing it then the answer is of course money an aftermarket carb is less than twenty dollars while the OEM One is three times that amount and unless you have a muddy Tree in your backyard that's a lot to pay for a part that does the same thing as the cheaper item so as you just saw the metering diaphragm was in terrible condition just like the pumping diaphragm so for me that was a pass to order a new carb now if you've seen my past videos you know I typically work by percentages what I mean by that is if I have a slim chance to get something working I'll try a different option and for this one with both diaphragms in bad shape the chances the original car was going to work was very slim so I just saved myself the headache of an attempted repair and failure so this carb kit did come with a tool that I would need to turn the special screws they use to adjust the low and high adjustment screws now depending upon how the trimmer runs after we get it working again I'll then decide to either make changes to it or leave it alone also the last time I had to buy one of these cheap carbs the impulse port on the carb it was just a bit too low and was making contact with this part of the fuel tank so hopefully we don't have that issue with this one now the old gasket between the carb and the engine is still stuck to the old carb so I'll just replace it with one that came in the kit then we'll slide the carb onto the studs and hopefully it'll clear the fuel tank and then we'll be very close to getting this trimmer working again I know a lot of the viewers will mention that if I want to increase my chances of a successful carb cleaning I should just get an ultrasonic cleaner now even though I think they're great at cleaning things like jewelry and nuts and bolts I do have some concerns about using them on something like a carb so when cleaning a carb in an ultrasonic cleaner you're trying to get dirt and old gummy fuel out of the fuel passages but on the outside of the carb you're still going to have some dirt and oil especially if you didn't bother cleaning it first thinking the ultrasonic was going to do the work for you then when you use the machine loose dirt and oil might find its way in parts of the carb you may not want it in so yes you may get rid of the blockages but you might make new ones if you're not careful basically the ultrasonic might work but it's not a guarantee either and for me getting a new aftermarket carb is yielded a very high success rate now I'm not going to tell you which way is better but in all my attempts the one thing I try to avoid doing is having to keep trying to clean a carb with little to no success so for me if I clean it once and it doesn't work I'll typically just bail on cleaning it so if that's what you normally do then why aren't you trying to save this one the main reason is the pumping diaphragm if I find a diaphragm that's about 50 gone I might try and save it this one however was far too gone to try and save and if I wasn't going to be able to save this one I wasn't going to waste my time by even trying it the last items we need to install are the new air filter followed by the air filter cover after that we'll then put some fuel into the tank Purge the fuel system of any air and then try starting it now I probably should have put the old fuel back into the tank but I kind of forgot about it so my fuel will have to do once I get a few ounces of fuel in the tank the first test is whether or not The Purge bulb will fill up with any fuel if the bulb doesn't get any fuel in it when pressing it check the fuel lines or fuel filter for any issues ours is filling up nicely so it's now time to choke the carb and try starting it all right [Music] okay [Music] so it started and ran fairly easily and the only real issue was that the idols set much too high on the new carb but after a slight adjustment we got it down closer to where it needed to be so initially I don't think I'm going to make any adjustments to the carb and the reason is because it's acting just how I wanted to the only thing left to do would be to let it cool down and do another test start and if that goes well I think it'll be ready to go back to my co-worker I know a lot of the viewers who see this are not going to agree with my choice mainly because this machine is a high quality one but like I said it's a money issue and if you have the budget to get an oem carb then do it but if you don't and you need to get your trimmer working again for this mowing season then you do what you have to and if that means getting a cheap carb then that's what you have to do then so if this was my trimmer that I paid full price for instead of my co-workers what would I have done if you hadn't guessed it it never would have gotten to the situation in the first place but let's say I had to take a long two-year vacation to a place I didn't want to be and then came back to it what then the answer shouldn't surprise you I'm cheap I'm gonna get the aftermarket carb so my question is what would you have done in this situation would you have made a case to the owner to get the higher priced OEM carb or would you let them decide and if they decided against the OEM carb would you agree with them remember we can't all make the best choices we can only make the ones that felt right at the time thank you for watching I really do appreciate your time here please feel free to ask me any questions about this project or about your own projects and I hope to see you in the next video

Channel: Home Garage

Views: 205,925

Keywords: stihl, husqvarna, echo, ryobi, troybilt, troy, troy-bilt, strimmer, trimmer, homelite, poulan, craftsman, craftsmen, weedeater, weed, eater, grass, trim, edge, edger, yard, yardman, will, not, start, won't, run, starting, running, starts, runs, work, working, works, fix, problem, solve, help, diy, garage, inside, house, home, spark, gas, fuel, line, mix, cycle, 2 cycle, 2 stroke, stroke, can't, why, my, carb, carburetor, rebuild, kit, rebilt, shaft, pull, rope, string, engine, kill, switch, rev, rpms, speed, head, on, off, worn, out, blown, broke, pole, saw

Id: RAqWSEryPUg

Length: 12min 43sec (763 seconds)

Published: Fri Apr 21 2023