Purge Bulb Won’t Fill Up With Fuel? Here's Why!
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- เผยแพร่เมื่อ 15 มิ.ย. 2024
- If your Honda, Stihl, Husqvarna or other engines purge or primer bulb won’t draw up fuel, these are the reasons why. Diagnosing and repairing a 2 stroke carburetor can be difficult, but these tips will allow you to service and repair yours at home and save you money, time and frustration!
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#Hondacarburetor #stihlcarburetor #husvarnacarburetor #primerbulb
00:00 The purge bulb won't pull fuel
01:47 2 stroke carburetor disassembly
04:54 How to service a 2 stroke accelerator pump
07:10 How a purge bulb works
10:37 How an accelerator pump works
13:30 How to delete an accelerator pump
19:36 How to replace a 2 stroke carburetor - ยานยนต์และพาหนะ
If this video helped you, please consider clicking on the THANKS button above to support my channel 🙌
Que sucede cuando el bombillo se vacía al rato de usar el trimmer?
Is there a way to send a donation and bypass TH-cam? I hate the thought of giving TH-cam any portion.
Hey, thanks for considering, any method, PayPal, TH-cam, patreon etc will all take a small portion sadly, but after all we get to use their platform for free which is pretty awesome :)
I’ve fixed loads of chainsaws & strimmers & didn’t know there was an excelerator pump in some carbs, well done & you learn something every day.
Great to hear you learn’t something new. Always good :)
I'm VERY impressed by your knowledge of small engines. You did a wonderful job of diagnosing the problem. Thank you to taking the time and trouble to record, edit, and post this video. Much appreciated.
It’s a pleasure Kevin! Comments like yours really mean a lot to me as you are aware of the extent of the effort videos take to make. That’s awesome and thank you again!! It gives me the motivation to continue :)
The breakdowns of what is happening inside the carb, the drawings to understand it better, the first grade way of explaining things. This guy knows what he's talking about. Been struggling with my husqy for the weekend and this is it, the problem and the solution. You've saved me $20 on buying a new carb. You are awesome and I appreciate the very well informed explanation. Definitely subscribing after this one. Cheers mate!
Thanks mate :) glad you enjoyed it!
Well done sir I learnt a lot and great to see a young person fixing stuff instead of throwing it away.
Thank you John, I do my best to save everything be it a beautiful vintage engine through to a fuel filter. As silly as it sounds, everything is stupidly expensive out here and if you order it online it’s 2 - 8 week wait!
This was exactly the help I needed. You are a very good teacher in addition to being a mechanic. God bless you sir.
Thank you :) glad it helped!
This was so beautiful to watch. Can you please do a video on adjusting the low and high fuel metering screws?
@@onthemudd1 hey, I have :) STIHL’S OFFICIAL 2 STROKE CARB TUNING PROCEDURE.
th-cam.com/video/UyngDl_2km0/w-d-xo.html
@@VintageEngineRepairs thanks you for this...
@@VintageEngineRepairs thanks for sharing the link with me and others
This is great info that so many young techs never learn. Having said that, from a repair shop point of view its quicker and cheaper for the customer to just replace any carb that won't prime.
Spot on Scott, this isn’t something the average shop would be able to justify. It’s something I’d recommend to a home owner wanting to get their machines working again or even someone running their small engine repair business that is offering an alternative to an expensive oem carb when costs need to be kept down :)
I calculated that what I’d charge for my time to do this would be 3x cheaper than the customer buying an oem carb. That said my overheads are minimal compared to a shop of course!
@@VintageEngineRepairs BINGO!
For now it's economical to replace the card but it won't be as new anti-petrol regulations set in making all of this impossible to maintain without critical knowledge.
You sir are a backyard university professor! Thanks for a wonderful video.
Haha that’s funny! Thanks :) glad you enjoyed the video!
Fantastic Job.
The amount of time, energy and information you placed in this video is a gift to all..
Not only did I learn a great deal, but to think on the amount of items that may be repaired / rehabbed, then placed back into service rather than being thrown away, was very inspiring to me.
Thank you so much, I really appreciate your kind words! Im pleased you enjoyed the video!
I learned about the innards of a carburetor today. I knew they are complex, even the simplest ones. Thank you for the education.
Great stuff! This video will teach you everything you’ll ever need to know about these cube carbs :) I hope you enjoy it! th-cam.com/video/_4K6dBQTeek/w-d-xo.html
19:57 Happy Days! You are the 2-stroke genius Tom! Now I have to find all of those I just replaced with new and see if this fixes them!!
Haha thanks Kenny, I still have a lot more to learn though! Have fun with it :) if I find the o-rings I’ll send them your way. I believe they do come in a few sizes, but we’ll see!
Thank you for the explanation of how to repair these carbs.
You’re welcome :)
Provided my check valve still checks, this is what's wrong with my carb. Thank you for the video. Well done!
Thank you! I’m glad it helped :)
Ive been scratching my head as to problem cause on my fs40 carb... watched this ... straight out to workshop and boom fs40 priming and running sweet!! You absolute star just saved my a fortune.
That’s fantastic! Pleased for you :)
I am very impressed with your knowledge of carburetors. The diagnosing of the problem and graphic illustrations are simply awesome. Thank you
Thank you! I really appreciate it!
I'm very impressed by your knowledge of small engines. I've worked on them all my life and never knew anything about using a hand pump to pressure test the fuel system. Subscribed!
Thanks for the kind words and your sub! I’m glad you enjoyed it :)
Dude! This was great. Subbed on the first vid. I love that you know the form, function, proper description and definition of even the slightest nuance of a carburator...and you can't remember to say "SUBSCRIBE"! Bloody marvelous, mate.
Haha thank you! Much appreciated :) I have always felt that people will subscribe if they like your content. No amount of asking will change that, it just gets annoying.
You really enjoy doing this and figuring out how to fix it
I’m impressed with your skills and knowledge 😊😊😊
I do :) thanks for watching!
Great video. I know quite a lot about carburetors, but you are definitely on another level. Thanks for sharing, and I'm going to have to check the rest of your videos. Cheers.
Hey :) great to see you over here, I love your content!
Thank you so much for all your input on the 2 cycles. I've been working on him a long time. And I just learned some new things from you. Please keep up the good work, and thank you again. Yes, i'm across the pond, hello
You’re very welcome! Glad you enjoyed it :)
Rivetting stuff! Beautifully explained and videoed, even my wife watched it! Many thanks
Very kind thank you!!
I have spent hours trying to solve this issue. I ended up replacing the carb but that is an admission of defeat. I will try again with my new found knowledge and win this time. Thanks for teaching me.
Glad you enjoyed it!! :)
I give myself a lot of time outs, but I eventually get it done. So don't give up, just take another break. You got this!!
Excellent!I've just spent 2 hours today with this problem. Luckily i have orings.if it doesn't work,plan B,nail varnish.
I'll come tomorrow with an update.
Thanks again!
Fantastic! That’s great news :) keep me updated!
Excellent description and execution of a tricky repair thanks for that insight.
Thank you for watching and commenting, I appreciate it :)
Thank you for the information. I like the way you took the time to go over the carb operation.
Thank you!
Well done Tom, thanks for the technical information and hacks.😊
Pleasure Rick :)
I've learned so much from your detailed videos, thanks for providing them to the tube!
You’re very welcome!!
Thank your for the video! My BRAND NEW replacement carb has got to be sucking air - as evident by some bubbles in the fuel line. This video gave me a few ideas to chase after. Thanks a Bunch!
You’re welcome! If it’s an aftermarket Chinese clone, check everything inside it :)
Hey there, I just happen to catch this video as I was scrolling . I really like how you explain what you're doing and how it works, that makes more sense than what I've heard. The drawing helps, and the close ups with magnified. That helps when it's so small. Thank you
Thank you! I’m glad you enjoyed the video and it made sense! Sometimes it can be hard to convey everything required :)
Yes you did great, maybe speak a tad louder or have a mic closer to your mouth if possible. But yeah, I do a little small engine repair, I use TH-cam as a guide. For refreshing my skills. Most videos don't go into depth of taking it apart and explaining it more thuroughly as you have. So I'll definetly be watching more of your vidios. I took small engine course in HS. I was the only female. So we had to lock my engines in shop techs office to protect it from the guys vandaling it. But it's been 30+ years. So these videos are great refreshing for my memory lapse of time. Thank you! 😎👍
@@suzanemartin8242 so sorry to hear of how it use to be. I have heard many stories of the nonsense that use to go on back then. Thankfully times have changed and we see more woman in the repair industry and flourishing. I’m so pleased you didn’t give up. I’m always here to help when I can :)
Strange as it seems, it hasn't changed that much. The guys make it super hard to keep jobs. I aced the small engines even thou. But got crazy and went into auto body r/r. Again only female. My husband scared the poo outta those guys, after I reported my projects being damaged by vandal. That was college. I finished in the top 3 in college. But I was lucky if I was hired. Let alone they savataged my work. So in the NW, it's still very hard for a female to even get started in mechanical world. But I got burned out on fighting for employment. Had to support my kids. Couldn't keep going on. So I just enjoy it for my own good. Nice to know skills.
A master of your trade. Thank you for a real repair video!
You’re welcome, thanks for the kind words :)
I did not know that these carbs have an accelerator pump.
After watching your video I pulled the carb, attached a temporary line to the inlet and immersed into fuel mix. The primer bulb would not lift any fuel. I then opened the throttle shaft and applied a few drops of 30w oil past the flat to cover the accelerator pump piston, closed the throttle and tried to prime again. The bulb immediately lifted fuel and filled. This was a quick way to confirm that the O ring was at fault. Upon disassembling, the O ring was brittle and broke in 2 pieces when removing. I replaced the O ring with a generic nitrile 1mm x 3mm id. All is working as it should now.
Thank you for your clear and concise explanation.
You’re welcome mate, that’s a fantastic test you mentioned with oil, I must keep this in mind for next time, thanks for sharing!
I've benefitted from a good number of your videos. Thanks very much indeed.
You’re welcome!
EXACTLY the problem I had! So grateful for this video amigo 😊 thank you!
You’re welcome! :)
Very clever, informative and creative ... have looked at lots of channels to try and find accelerator pump fix .. because everyone says Throw Carby away, its Cheaper (but a waste) ...
PS I would have liked to have seen the symptoms prior to your fix, is all ..
👍🇦🇺
Awesome :) glad you enjoyed it! Yes that would have been good, but because it wasn’t sucking any fuel it wouldn’t have started :( thanks for watching and the feedback!
This is the most useful video. Congratulations and thank you !!!!!
You’re very welcome!
Yes in joyed watching the video,great job showing and telling.if I tried that I wood miss it up I think, but thanks again for showing telling your good at it keep up the good work see ya next time see ya bye.
Thanks for watching, pleased you enjoyed it 👍
Like a pro! Great job brother! Keep up the awesome work!
Thanks mate :)
Thank you for sharing your knowledge! Very impressed and subscribed!
Thank you!
Thanks so much mate. sure enough was the same issue as this video. You were walking past my place and stopped in and gave me some advice. I would love to come round and get a masterclass in 2 strokes if you were ever interested.
All good mate, you’re welcome :) it was fun and it’s always good to meet people with similar interests!
Lawn mowers as myself love y'all videos 🤜🏾🤛🏾 thanks my brother
Thanks mate!
Absolutely brilliant explanation best I've come across
Glad you enjoyed it! Thanks for the kind words :)
Thanks for this ❤ I have spent countless hours on Stihl carbs trying to fix a non priming problem without realising that this accelerator pump even exists. i have seen the small screen in the repair kits and wondered what it was for but they never included an o ring 🙄 have bought a pack of 1x3mm o rings as another viewer described. No amount of carb cleaning would have solved this issue. Thanks again 🙏
Update, got to the accelerator pump then lost it as the spring launched it into the garage somewhere 😂😂
Oh no 🤣
Not many know about it :) glad it helped!
@VintageEngineRepairs I'm extremely impressed by your expert knowledge on these units. In particular your ability to perform a bespoke repair by using your understanding of the pump and sealing dynamics is a skill I'd really love to develop
I've been repairing power tools and small engines for a couple of years now but still don't fully understand carburettor operation. Are there any books or resources you used to get your knowledge up to this level?
Thank you for your kind words :) I have videos on how they work and more coming out very shortly. Start with this one :) th-cam.com/video/_4K6dBQTeek/w-d-xo.html
Don't have this problem at the moment, nonetheless watched and admired the very clever diagnosis and resolution process.
Thank you :) much appreciated!
Thanks Tom I am doing a Stihl bower this week. . Bruce from Canada.
Great stuff Bruce! The blower is in good hands with you!
man i've watched a lot of videos on this ,this is the first one that makes sense
That’s great :) glad you enjoyed it!
Spot on... ! since the introduction of 10% ethanol in the UK I've had more trouble with diaphragms and fuel problems with 2 stroke engines.....nightmare
Yes, it’s terrible isn’t it! Good for business, not so good if you’re a customer!!
Great explanation Tom, thanks. 👍
Thanks John!
This is exactly the problem I am having with exactly the same carb!!!! How does YT know? Thanks for posting!
Crazy! Glad it helped :)
Brilliantly explained video . I am amazed at your knowledge and explanations . I have several Stihl tools and to be honest I never did understand the intricacies of how a carb works . I usually replace diaphragm and gaskets , fail , and then replace carb . I have a Stihl sh86 blower that only fires once but fails to start . so I have 100 psi of compression , a good spark , replaced all carb parts and after a half day episode it still does the same . Fires once and no more . I have a new Stihl blower but would love to get this old one going just because I believe it is something very minor . Just a great video , I would love to know where you obtained all this technical info , really impressed .
Thanks for the kind words, a lot of what I have learnt has been from stihl manuals that are for
their technicians, also through research online, good mentors around me who help and and frustratingly obsessive personality that doesn’t let me give up until I understand something.
Re your 100 psi. This is actually too low for a 2 stroke ope engine to run. They say 120 is about the lowest and even then it won’t run well (if at all). The caveat here is if your compression tester is not designed for small engines, that could be why it’s low, even if the engine is good. Too much to explain in a message, but here is a video on the topic - th-cam.com/video/M6eXO6n8hhg/w-d-xo.htmlsi=7zrVpHYwLpbOuqhQ
Note on some occasions 2 stroke engines are low compression (70 psi and they’ll run) but not in outdoor power equipment. They need about 150psi.
Back again , thank you for your reply . I will study your recommended video and I think it will be prudent to check compression on the new blower . Both are Stihl sh86 models, the problem one I have for maybe 12 years .
Just for your info , the new one gave a slight problem in that the outer stop lever stuck down in the off position due to the very cold weather and the tight fitting of lever . I removed the upper hand , greased and freed out a bit and that solved the problem . The lever is designed to spring up into the start position automatically . Initially I did nor realise this and on account of hearing that the petrol quality has changed I believed that was the problem .
Anyway thank you again .@@VintageEngineRepairs
Thank you. I have a Stihl FS45 line trimmer that's just out of warranty. The bulb wouldn't fill and would remain completely dry, just like the one you demonstrated. The carb is ostensibly identical to that in your video. Pulling it apart, cleaning and reassembling it, didn't initially solve the problem. Eventually I took the cover off the fuel-pump side, as you demonstrated at 2:40. I couldn't see anything wrong with the rubber gasket and its two flapper valves (I presume). Regardless, I removed the thin rubber gasket. It was well adhered to the metal surface and I feared I was going to tear it. Anyway, no damage seemed to be done in its removal. As I could see nothing wrong, I reassembled that section and the rest.
After reassembly of the carb I put the intake pipe on my lower lip (dry) and pressed the bulb a few times. I could now feel it sucking. My fingertip wasn't sensitive enough to detect it.
I put the carb back on the line trimmer and pressed the bulb a few time. It now filled with fuel. I'm not sure what fixed it and how.
Unfortunately, the trimmer still won't start.
There was something I noticed on the metering side. The diaphragm looked lumpy, as though it had tried to expand, sort of like when paper dries after being wet. The other thing is that the bulb, once filled, resists further pumping. I don't know if that is normal.
Thank you for your video; I have liked and saved it.
Thanks for sharing! It could be your main nozzle!
Very informative video. Think it would help if you bought a box of assorted size rubber o rings it’s got me out of trouble many times.
You won’t believe it, I had the size all along, in exactly that - a box of nitrile o-rings. I don’t know how I missed it! Thanks for watching :)
Exactly what I was looking for thanks for the tutorial!
Awesome! Glad it helped :)
Really good tutorial on operation.
Thank you :)
Hi Tom, i have just done a Stihl FS 38 same problem no priming but i have just put a Chinese carb on, there is few few videos on them type of strimmers not priming, but you have done well finding out what the problem is, the small seal is that about the same size that @henrymurawskibigdogrepair was looking for and got
Thanks Nev! I believe it’s a different size, but you never know! Yeah you can chuck a new carb on, I like the challenge of fixing it though haha.
@@VintageEngineRepairs you did very well on that one 👍👍
Amazing detail - THANK YOU - old git, UK
Your welcome!!
You didn’t explain that the reason the engine was bogging was because the accelerator pump was now disabled, and the carb had to be adjusted to richen up the low speed side to compensate for that lack of additional fuel upon opening the throttle.
I try my best to cover everything, but sometimes I’m on auto pilot.
Really I have had that problem and was able to buy a o ring kit from Harbor freight and in that kit is several o rings that can be used. Just a thought if you really want to fix it for a little bit of money you can. But like the one guy said you can order a new carburetor for cheap to and the one’s I buy come with hoses and filter. Easy peasy.
The key is that they are nitrile or other petrol resistant material. If so and they fit, you’re good to go! :)
Really comprehensive. Thanks!
You’re welcome :)
Great video! I might add that if you are in the US, you will likely be dealing with ethanol in the gasoline, the alcohol in which will destroy nail polish. So use a product like Seal All that is resistant to the alcohol.
Good advise! I wasn’t sure if alcohol will dissolve nail polish, thanks for sharing g
@@VintageEngineRepairs Recently found your channel, some great info in all those video's. This a particularly helpful video explaining the possibility of an air leak at the plunger o-ring - not necessarily just the idle and main jet non-return valves allowing the purge bulb to suck air, nice work!
Since the introduction of E10 fuel here in GB, my use of nail varnish when resealing welch plugs has had to stop. Nail varnish seemed to be ok with E5 fuel. Have you noticed that the original welch plug sealant used by Zama and Walbro has been falling out and blocking jets/valves for some years - I wondered if it was being affected by the E5 fuel.
I've just done the same seal up job with nail varnish on an FS85. With the small surface area of varnish actually in contact with fuel I'm hoping the job should last for a reasonable time. We'll see...
Great video man fixed my problem
Awesome!!
Having problem with mine as well. Thanks for that info
No problem 👍
Great Video... Great Camera Shots... Great All Around... You're a Master at Your Trade... Subscribed...
Thank you!!
Dude. You are the man.
Haha thanks!
Liked, you are amazing. On my trimmer. I prime the bulb. Crank the engine and it runs perfect for maybe 3 mins then stops You have to reprime and crank again. Same thing over and over again. It's like the bulb is losing its prime. Any idea what might be happening? Haven't seen my problem discussed on the web. Thanks in advance.
Hey! Thanks for the kind words. I’d personally take the carburettor apart, put a new kit in it and maybe give it a tune. Check fuel lines and filter too 👍👍
Very detailed video 👌👍
Thank you!
Great info!! Learned something new thanks!!
You’re welcome!!
Very interesting. Currently one of my units has a bulb not filling or occasionally filling. So far it hasn't affected the performance so it's a no touch at this time.
Interesting! So long as it’s not affecting anything you’re probably better to leave it, you may add a problem 🤣
Top job mate. If the accelerator pump can be disabled, why do they put there in the first place?
Great question! I’m only guessing here as I can’t be certain, but with the limiters in place and the use of an accelerator pump they can have it set leaner at idle and still get good off idle acceleration. However I remove the limiters so can get past it. Notice at the end of the video I say it’s a bit lean and richen it up? That could be the requirement. Though honestly I can’t tell you, I’m simply guessing!
Good knowledge!😊
Glad you enjoyed it :)
GREAT Video. Very informative!
Glad you enjoyed it!
thank you this was great video
You’re welcome!
Thanks for your knowledge
You’re welcome!
Great vid again. Perhaps try to measure o-ring size and order range of viton universal o-rings. Otherwise press in a small rubber plug as alternative?
Thank you :) yes they’re 3x1 mm 👍
Very interesting Tom
Thanks Al!
Great videos and info, thank you
Question : a 2 cycle carb, off the machine, both sides of the Venturi blocked with rubber the pulse and fuel inlets plugged. If I try to pressurize I get leakage around both butterfly shafts on both sides of the carb. It’s a Zama C3 EL18.
Is this normal?
Thank you, Trying to learn
Yes :) it’s not abnormal to get a very small amount of leakage there. It’s no big deal :) if it’s leaking really freely then it’s not ideal!
Thanks for sharing
My pleasure! Thanks for watching :)
Like your videos.I am wondering were do you get the small check valves that are in the metering area.I cannot find the parts on the diagram
Thanks! They’re known as “main nozzles” on parts lists :)
Hi great vid thanks. Couldn’t you replace the O ring with one out of a box of assorted O rings ? I get why the Stihl kit was cost prohibitive as so in the UK I Worked out their price strategy they simply charge £10 per part hence making a replacement carb more cost effective. Does the nail polish fix last for a long time ? Or does the fuel rot it ? Many thanks Nick
Hey loads of great questions! Over time nail varnish will dissolve in ethanol fuel. If you’re running non ethanol fuel it won’t. You can absolutely just replace the o/ring if you have one, but it has to be fuel resistant, so nitrile or viton. Just for your reference, they’re 3x1 :)
Good job bro
Glad you enjoyed it!
Enjoyed your video
Thank you!
Doesn't the vacuum from the piston/crankcase also play a part in getting fuel to the CARB. too?
That’s the only thing that gets fuel to the carburetor, yes :) the impulse, that the piston rings create, is what pumps fuel. The Venturi effect doesn’t draw the fuel into the carb as much as it does draw it out of the metering chamber haha.
I have a Zama S68 241A carb on a BG86 blower.
Ordered some 3x1mm rings but they're too big enough to fit in the bore.
I was sure that's the size I needed but it seems not.
Can you advise what dimensions they're supposed to be?
It's such a nice blower and i got it for free so id like to keep it as it was built if possible.
Thanks so much for your videos, even after years of experience in small engine work i learn something new quite often, even if it's just a different way of approaching an issue.
Nice one!
Hey mate, thanks for the kind words! Sure, for that machine / carb you need a 2.3mm x 0.8mm o-ring.
@@VintageEngineRepairs hahahaha, cheers mate.
I ended up cutting and gluing the big rings.
Ill order some of the right ones.
Was sure id used 3x1 before and saw that size mentioned in the comments on this video!
Must be losing my marbles!!
Thanks again fella.
Much appreciated.
Best reference on TH-cam, without any doubt!!
Like so many others, I found your video really helpful, thanks. About 5 years ago, I replaced the carb on my Stihl KM55R with a Stihl original and now have this same problem back again, so need a cheaper solution. Didn't fancy the nail varnish trick, but thanks to you have just ordered some nitrile 'O' rings on eBay, so we'll see how that goes. I do, however, have one query and am a bit reluctant to question your excellent description of the way the fuel system works, but here goes. Testing on my KM55R led me to believe that pressing the bulb raises the air pressure in the fuel tank, which then pushes fuel back through the filter and up the inlet tube to fill the bulb, rather than by creating a vacuum as you describe. Am I completely wrong on this or do some machines work differently? Certainly, if the filler cap is not closed tight, no amount of bulb pressing delivers any fuel up the inlet tube to the bulb, since there is no pressure in the fuel tank.
Hey :) hmm sounds like you may have a leak in the carb, if will push fuel back into the tank, but because you’re removing as much as you’re putting in, you’ll maintain the same pressure. Besides, you’d have to pump about 50-100 times to change the pressure enough to build it up in the tank as there is a lot of space haha. Best of luck!
Hi, thank you so much for your reply. Your thoughts are exactly the same as mine initially, i.e. how could a few pumps of the bulb increase pressure to the extent that it pushed fuel from the tank up to the bulb. That said I can find no other explanation for the following: With the carb in place, if I disconnect the lower hose and pump the bulb, fuel comes out of the disconnected pipe. Since this pipe is fed direct from the tank via the fuel line and filter, I can't see how else fuel can come out of it, unless it is being pushed out by pressure in the tank. Furthermore, if I release the filler cap, no fuel flows, regardless of how much you press the bulb, since the fuel tank is no longer pressurised. I am really not trying to be argumentative here in pushing this point, but am keen to understand exactly how the fuel system works, so just repeated this exact test to be absolutely sure.
You are right that I must have a leak somewhere in the carb, which presumably is why fuel never reaches the bulb, when everything is connected correctly. Thanks entirely to your video, I now believe the 'O' ring on the piston is the culprit. Before that I had no idea that any of those parts existed let alone what they do!
@@brianwizard7092 it will certainly pressurise the tank, but not by a huge amount. Any press will have an effect, be it small.
Just to complete the story, my new piston pump 'O' rings finally arrived today. I was a bit uncertain since they seemed indistinguishable from the existing ones on the carb. However, I went ahead and replaced it on my original carb first and immediately got the bulb to fill, so went ahead with doing the same on the replacement carb that I'd fitted to the KM55R a few years ago. That, too, now works perfectly and so I have ended up with a working carb on the power unit as well as a spare, should the current one fail again in a few years time.
One point you might consider adding to your video is a warning about the spring loading of the piston when you remove the butterfly shaft. First time I pulled it out, the piston and spring shot out of the hole and disappeared over my shoulder into the depths of my garage. Fortunately, I found both bits, but it gave me a few nervous moments, whilst I was frantically searching for them.
Many thanks for both your knowledge and time spent making these videos, which have allowed me, personally, not only to save a few quid, but also avoided me junking yet another perfectly good carb that only needed a very cheap part to get it working again!
How do you know all this detail? I was searching for this type of information but couldn't find it until I came across your video. Nobody else that I could find had this level of detail about how this carburator works. You should make more detailed videos like this. Are you a carburetor engineer? Thank You!
Thanks for the kind words :) it’s a combination of research, reading manuals, reading stihl documentation for their mechanics, trial and error, forums and also good mentors around me :)
@@VintageEngineRepairs I had replaced the primer bulb recently and when my FS250 would run for a while and then want to stall out, but I could sometimes prevent it from stalling by playing with the throttle. I started to think that maybe I had the primer hooked up backwards, since it didn't seem to hold fuel. I tried reversing it and it would hold fuel then but I figured it couldn't be right because you wouldn't want to push unfiltered fuel into the carb, so I realized it must pull it through. But it seemed to only suck air. So when I found your video I realized that there was something wrong with a check valve that prevents sucking air from the air intake near the butterfly. Anyway, when I took out the the butterfly valve a little ball bearing fell onto my driveway and I dan't find it. So I just ordered an aftermarket carburetor to replace the carburetor with....but I know for next time.... :).
That ball bearing is the choke side, no accelerator pumps on the fs250’s. Funnily enough that’s the exact machine I’m working on as we speak. The sealant video was featuring it and the next video too. I needed a new carb as mine was so damaged by corrosion and no parts available. $250 Australian for a new one!! Had to go AM, brought it today off Amazon, I’ll do a video on it haha.
@@VintageEngineRepairs I realized it was the choke side shortly after I mentioned it. I found the ball bearing with a headlamp at night and put that back together. I haven't had a chance to take apart the throttle side yet. I am soaking the membrane in DOT3 right now. Can both membranes be soaked in brake fluid? They seem like different types of plastic... I really need to watch your videos more closely, so much detail to digest but I like to fully understand how things work and your videos provide that.
I’m not sure about the fuel pump diaphragm! I haven’t tried it. If you give it a go, let me know your results :)
U gr8 man I like it
Thank you!
My KM55 kombi motor ( basically the same as the FS 55 power head) had a bad check valve inside the metering block. Also had a leak in the metering block around the hose connection. I also have an inconsistent idle ( going lean on and off, with idle speed rising and falling) on my old still 028 chain saw. I’m going to check that check valve in the main nozzle. I’ve done everything else. I may also have too much slop in the throttle shaft, and it may be sucking air there. Thanks for your input depth videos on troubleshooting these carbs. They are the best on you tube.
You’re welcome and thanks for the kind words! Keep me posted
How much do you charge for the labor , thanks for the video is very helpful.?
To do this job? If it was a customers I’d add a new o-ring. It’s about 15 mins work so about $15 Australian.
Magnificent . ThanX !!!
Pleasure :)
What would cause the bulb to be hard and not fill with fuel? After a few pushes the bulb will stay down but still no fuel. And its an Echo 2620 if that helps. About 6 months old. Im assuming the check valves under the primer bulb?
Yep! Can be the valve not letting fuel in that is blocked. Could be a stuck metering lever, very clogged screen, blocked fuel line. Something is blocked in the circuit :)
I think my problem is a worn o-ring on the accelerator pump piston. I've ordered some o rings, but in the mean time, I was wondering if there was a way to 'mod' the piston to reduce wear OR remove the need for the oring? The bore is 4.00mm but the piston is only 3.75mm. That alot of play for such a small size. I wonder if a better fitting pistion ( without o ring ) would work better? Another thought was to fit a second o ring at the other end of the piston to keep it square int eh bore, better. thoughts? Steve
It’s not common but you may have a worn piston. You can buy a pump piston kit :)
Greetings, and thank you for your effort and explanation, I learn something new in each of your videos, and I've been doing the same for 8 years. I have a question, I have a couple of the same carburetors as the one in the video, I'm really struggling with one, it also didn't want to pump fuel, so I washed it in an ultrasonic cleaner and of course with the appropriate liquid. After that, the pump worked and now it pumps fuel like new, but I have a problem with adjusting the carburetor. when I set it to work well, I leave it for half an hour, after that half an hour I go to turn it on, it starts right away but does not want to accelerate when I give it gas, it chokes. and so in a circle, I adjust it again and it works. but the next day it may not work. diaphragms and check valves are good. If you could give me advice on what else to try, I would be very grateful :)
to add, I didn't seal the acceleration pump like you did, but I put everything disassembled in the ultrasonic cleaner, after which the pump drew fuel normally, so I thought there was no need to seal it like this when it was working
Sure, I think your best bet is to pressure and vacuum test the machine :)
Dang... God job! how much time did you work with these to know all this stuff?
Over about 4 years, glad you enjoyed it :)
@@VintageEngineRepairs .That's awesome... I'm hoping I can ask you some questions from time to time... Hey, do you believe in replacing the check valves as opposed to getting a new part or carb? I'm thinking it Could be done easy but I can't find parts.
Did you leave the o ring out or did you reinstall it along the plunger? Thanks for the help!
I re installed one before selling it so it was back to factory oem.
@@VintageEngineRepairs thank you
So, what do you think caused the o ring to fail? Cheap fuel or dry rot from lack of use?
Na just age, it happens - it’s. wear item
Hi Tom, does the same testing with the fuel line sucking and pushing apply to fs120 carburetors?
Reason why i ask is because I'm not seeing a point for the accelerator pump to come out if i remove the throttle rod.
If you cannot see the little hole for it either side of the carb, then no there isn’t one. If that’s the case, it could be your main nozzle check valve not sealing, your fuel filter may be out of the fuel, damaged lines of most commonly if you have taken the carb apart, the metering side gasket is leaking :) hope it helps!
@VintageEngineRepairs there is a white plastic plugged hole on the choke lever side, maybe that's it?
Perfect. ...
Glad it helped!
Hi thanks for the video, i like to try and fix things too theres no fun to be had with cheap chinese copy carbs unless you like retuning your machine every time you use it! I would rather a serviced genuine carb.
Can we just uae a normal rubber oring out of a cheap oring kit, or does it need to be viton or similar? Another thought might some dot3 brake fluid ir silicone spray rejuvenate/swell the oring enough to get it back to size
I have a video on rejuvenating the metering diaphragms but not o-rings. Yes they need to be viton, nitrile or the like or it will fail :)
@@VintageEngineRepairs thanks for reply :) I have seen your video on diaphragms, will try a few different things I'm about to tackle an fs45 this arvo! Maybe a very thin slice of 3.5mm od fuel line would do the trick?
Someone suggested that but I haven’t tried it :) let me know how you go. Use 3mm as that’s the original o-ring size.
Works on some things, thinking would be an idea while servicing carbs to just sit a dob of silicon spray on the check valve for the rubber to soak up, just for good measure! prevent maintenance ..or just Asking for trouble? :) what do you think
Great video. Very thorough. That said, I will just purchase and replace the carb as I see a lot going wrong trying to rebuild.
That’s a shame, it’s not difficult :) give it a go!
What can go wrong if you follow the instructions in the many thousands of videos teaching you what to do?
You obviously have some interest in the topic or you wouldn't have clicked on the video.
The world needs more people with knowledge, not more landfill.
Maybe a dumb question, wouldn’t a replacement oring from an oring kit do the trick?
It depends firstly on the material, many kits are just rubber orings and will fail right away, the other is it’s a very unique size. Therefore it’s not in any kit i or anyone else I know, has found!