This Stihl Trimmer Doesn't Have The Power It Used To

this steel trimmer belongs to my dad and he's had it for the last several years the best part is that it looks to be in really good condition with very little damage to it it's been a fairly good trimmer in the last seven years he's had it but recently he's been complaining about how hard it is to start and unfortunately it's gotten worse now we'd like to keep it running and use it until it dies hopefully we're not at that point just yet in today's video we look at this steel trimmer and the problem is that it starts and runs but it has some serious running issues first off it seems to be very unbalanced so it shakes a bit while idling the second is that it won't stay running once you get off the throttle and the last issue is it doesn't seem to have enough power and he's concerned that it might be wearing out and it might need to be replaced now i'm going to try and repair this trimmer however it may not be the exact repair you need to make to yours we'll explore other options later in the video now we're only going to mention what these other options could be we don't have enough time to look into them but if you need more information on these options you're welcome to ask as many questions as you need to now this trimmer is an amazing condition considering he's been using it for the past several years and how much he has to use it now he takes really good care of it and so far it's treated him very well i think it was last year that his complaint started and after another year he says it's getting really tough to use especially having to restart it a lot now if this trimmer belonged to a complete stranger i would normally suspect the fuel to be an issue either a mixture heavy with oil or that it was stale fuel but as you can see that's not the case at all the mixture is spot on and smells strongly of fresh fuel straight from the pump if you think the fuel might be an issue try getting some fresh fuel and then mix a fresh batch and see if there's any improvements the next thing i want to do is try and start it and show you the issues it's having one important clue as to how well the carb is working is how the purge bulb is working if your bulb is slow to fill or doesn't fill at all then it might indicate that the carb is having an issue pumping fuel from the tank now this one is working just fine which is very important to remember later on um now i didn't run the trimmer for very long but once it's been ran for a bit that's when the engine wants to stall off throttle as you can see it works just fine however it never really gets up to full speed and the shaking is not normal now a bad fuel mixture from the carb can cause the engine not to get up to full speed also a dirty air filter or one that's wet with fuel can cause less air to get through the carb causing the engine to run rich and causing the engine not to get up to full speed as well now this air filter does have some fuel soaked around the edges of the filter but it's not saturated it's also not dirty so i don't think this is our issue just to prove my point i'm going to start and run it without the air filter and [Applause] as you just saw there was no improvement in fact i think it was even worse without the air filter now i do want to rule out that the engine might be the problem by using my compression tester the tester will show how much pressure the engine can make and we can then generalize the health of the rings and the cylinder now to use the tester just remove the spark plug and screw the tester into the engine and then squeeze the trigger and then pull the rope several times or until the needle stops moving i want to see a reading well over 100 psi and the higher the better if the rings have a lot of wear on them it'll make less pressure and that would mean that the engine is somewhat worn out so the reading looks to be about 130 which is a fantastic reading considering its age what that tells me is that the engine is not worn out and the issues we're having are not likely related to the engine at all if we look at the spark plug we can also get a feeling of how rich or lean the fuel mixture is according to the amount of carbon that's not on the spark plug it looks like the mixture is correct it's not running rich with fuel or not enough either situation would cause our problems but since the spark plug looks fine i don't think the carb is the issue that leaves us with one possibility which of course is the spark arrestor screen at the exhaust tip for the muffler now a blockage in the screen would restrict airflow through the entire engine and cause all of our issues to get the screen out to inspect it all we need to do is unscrew it out of the muffler so here's the screen and surprisingly it's not as bad as i was thinking it was going to be in fact it's not even clogged up enough to cause our issues i've seen some with more build up than this one and they all ran better than this one now you can see through the screen from almost every angle so i don't think it's the issue either i'm just going to put it back on and then consider adjusting the car because that's the only thing i've got left to do now the fuel adjusting screws are right below the bulb the screw closer to the engine is the l screw and it's for adjusting fuel delivery at idle speeds and when squeezing the trigger now the h screw is the one closer to the air filter and it's for adjusting fuel delivery while the trigger is fully squeezed now the screw at the bottom of the carb is for adjusting the idle speed because when adding fuel or taking fuel away at idle it'll affect the idle speed so you need to adjust it accordingly to keep the engine from stalling now these screws have plastic limiters on them to keep you from turning them too much we have to take these off so we can make our adjustments and then replace them later on luckily these can easily be taken off with no modifications before we start turning them i want to see where each one is set out that way i can put them back where i found them to do that just count how many turns it takes to bottom out the screws and then turn them back the same number of turns now these settings are different for each machine depending upon the altitude however there should be a default setting for each one now this one is not at the default settings so i have to wonder if my dad had it serviced at some point once i know what the settings are i'm going to start the trimmer up and then play with the screws and see how the engine responds to the changes i make oh um [Music] uh [Music] [Music] [Music] unfortunately i didn't get the results i wanted so i'm going to turn the screws back to where i found them so what just happened then basically i tried to adjust the l screw and it really didn't make much of a difference i then tried to adjust the h screw and even though it was responding somewhat i wasn't able to get the engine speed any higher what that's telling me is that either the carb has a serious problem and that's why it wasn't responding like it should or the problem isn't related to the carb at all that means i need to take off the carb so i can inspect it while doing that i can also replace the bulb with a new one luckily i do have a new carb in my stockpile that i had ordered for a different trimmer just in case i can't fix this one now i'm gonna skip right to the inspection of the carb if you need to see a full tear down video on the trimmer and carb check out the link at the top of the screen well basically what i found out was that there was nothing wrong with the carb every port was clear both diaphragms were in great shape however i still replaced the metering diaphragm just to make sure the inlet screen was completely clean and fuel will flow through it like it's supposed to that means the problem with this engine was not related to the carb so did i waste my time looking at the carb and the answer is kind of but at least we know it's in great shape once the carb is back together i then installed it back onto the engine for yet another test start and of course you already know what the results are going to be the engine is going to perform the exact same way as before it's still going to shake it will not get up to speed and after running it for a while it's going to have a tendency to want to stall after getting off the throttle although i did install a new air filter only because i had one on hand at least you'll be able to see how well the purge bulb works since the entire fuel system is completely empty but as you can see it only takes a few presses before you can see fuel into the bulb so it's working just fine oh ah um uh [Music] [Music] so as you can see it may not be running as well as it should be but it still works now it didn't stop running in the shot but i tried to use the trimmer after filming and it was doing just that so it was pretty annoying to say the least at this point i'd pretty much given up and was going to give it back to my dad but after looking at the footage after filming i soon realized i had missed something i want to take out the spark arrestor and show you what i missed and believe me i've never seen this problem before in fact i didn't think it was even possible now the screen itself is mostly clear with some minor build up on it but with this much surface area it shouldn't matter what does matter is where it all goes out if we look at the exhaust outlet for the spark arrestor you can see into the screen and see through it but what i wasn't looking at was the diameter of the opening what i didn't realize was that there was carbon buildup on the inside of it and it may not look like much but it was enough to restrict exhaust flow out of the muffler and engine i realized it when i happened to start it without my hearing protection on and realized that it wasn't all that loud just like a clogged screen even though the screen was clear now you can see it a lot better in this shot just how much it's being restricted that means we just need to clear the blockage and it should run just like normal again i thought it was going to be difficult but as soon as i touched the blockage the carbon just fell apart so here's a side by side comparison and as you can see there's enough buildup to notice a diameter difference now even though this is the first time i've seen this i don't want this to ever happen again so i took a drill bit that's two sizes bigger than the last one and enlarged the opening now it's not a huge difference but it's going to keep the build up from affecting the engine again this time i'll show you the comparison of the new opening compared to the old one i don't know what the original size was but if i had to guess it was probably around 200 thousandths of an inch and the new one is about 240 thousandths of an inch so it's an increase of about 20 percent now just for good measure i'm also going to burn off any of the carbon that might be on the screen and then use a brush to get rid of what's left now i can already hear someone in the crowd saying just throw away the spark arrestor screen and this won't ever happen again and i hate to say it but first off the trimmer is going to sound like a small chainsaw which is quite loud for residential use also it's for the owner to decide what they want to do so i'll leave that up to my dad and besides that the screen is there to keep sparks from leaving the engine and starting a grass fire so i wouldn't want that sort of liability on my hands if you choose to throw yours away that's your choice if you don't have a wire brush compressed air will work just fine just make sure you wear some safety glasses once i'm done i'll look it over and you'll barely notice a difference but it is a little bit clearer i'll then reinstall it back into the muffler and then we'll do a test start now i did look at the exhaust port on the engine and strangely enough it too was also clear just like the screen which still doesn't make any sense to me um [Music] [Music] [Laughter] [Music] [Music] wow [Music] i hope you could hear the difference between the before and after shots the throttle response was much better and of course the engine speed was much higher than before we cleared the exhaust another reason why the engine wasn't performing like it should have could have been as simple as the trimmer string putting too much load on the engine i've only seen this once before where they had a four-string head and was using the biggest line that could and had so much line out of the head that was cutting as wide as some mowers the fix would be to reduce the line count and size so it's not fighting the engine as much so in the end a blocked exhaust was the problem however i've never seen the tailpipe get clogged before the screen or even the exhaust port on the engine now a lot of people had guessed a clogged screen which of course was my guess as well but we were both incorrect but we were certainly in the right area so my question is would you throw away the spark arrestor screen to keep this from happening again or would you just clean it and maybe modify it instead like i did thank you for watching i really do appreciate your time here please feel free to ask me any questions about this project or your own projects and i hope to see you in the next video

Channel: Home Garage

Views: 50,842

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, bolens, arrestor, clogged, wacker, lawn

Id: dZeUcPcTqY8

Length: 17min 15sec (1035 seconds)

Published: Fri Aug 05 2022