Purge Bulb Won’t Fill Up With Fuel? Here's Why!

[@VintageEngineRepairs]

If this video helped you, please consider clicking on the THANKS button above to support my channel 🙌

[@mrodriguez5259]

Que sucede cuando el bombillo se vacía al rato de usar el trimmer?

[@wilsonmichaelnoland]

Is there a way to send a donation and bypass KZbin? I hate the thought of giving KZbin any portion.

[@VintageEngineRepairs]

Hey, thanks for considering, any method, PayPal, KZbin, patreon etc will all take a small portion sadly, but after all we get to use their platform for free which is pretty awesome :)

[@dannykimble7671]

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.

[@VintageEngineRepairs]

Great to hear you learn’t something new. Always good :)

[@DanielEngsvang]

I agree!. I have "done it ALL" i thought, haha. I also refuse to be "Beaten by a Two stroke engine" and anything mechanical really. - " Can We FIX it? YES We CAN!(Bob the Builder) 🙂😇😄

[@mikemetheny8652]

@@DanielEngsvang😅

[@karlschwab6437]

I have been replacing metering diaphragms, purge bulbs and fuel lines in these carburetors for years and never knew how they really worked and that they may have a fuel pump. Thanks for the detailed information.

[@VintageEngineRepairs]

You’re welcome! :)

[@kevinbyrne4538]

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.

[@VintageEngineRepairs]

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 :)

[@TheGreasyShopRag]

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.

[@VintageEngineRepairs]

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!

[@donmayberryjrsOPE]

​@@VintageEngineRepairs BINGO!

[@dontblameme6328]

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.

[@wilsonmichaelnoland]

This was exactly the help I needed. You are a very good teacher in addition to being a mechanic. God bless you sir.

[@VintageEngineRepairs]

Thank you :) glad it helped!

[@onthemudd1]

This was so beautiful to watch. Can you please do a video on adjusting the low and high fuel metering screws?

[@VintageEngineRepairs]

@@onthemudd1 hey, I have :) STIHL’S OFFICIAL 2 STROKE CARB TUNING PROCEDURE. kzbin.info/www/bejne/i6rRmHeilJeeo5I

[@onthemudd1]

@@VintageEngineRepairs thanks you for this...

[@onthemudd1]

@@VintageEngineRepairs thanks for sharing the link with me and others

[@1425race]

Well done sir I learnt a lot and great to see a young person fixing stuff instead of throwing it away.

[@VintageEngineRepairs]

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!

[@briantayes2418]

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.

[@VintageEngineRepairs]

Glad you enjoyed it!! :)

[@suzanemartin8242]

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!!

[@clintstevenson1214]

You sir are a backyard university professor! Thanks for a wonderful video.

[@VintageEngineRepairs]

Haha that’s funny! Thanks :) glad you enjoyed the video!

[@Avotec2000]

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.

[@VintageEngineRepairs]

Thank you so much, I really appreciate your kind words! Im pleased you enjoyed the video!

[@haneyoakie14]

I learned about the innards of a carburetor today. I knew they are complex, even the simplest ones. Thank you for the education.

[@VintageEngineRepairs]

Great stuff! This video will teach you everything you’ll ever need to know about these cube carbs :) I hope you enjoy it! kzbin.info/www/bejne/lWWuZ5d4hrmYm80

[@jafquist27]

Provided my check valve still checks, this is what's wrong with my carb. Thank you for the video. Well done!

[@VintageEngineRepairs]

Thank you! I’m glad it helped :)

[@joe42743]

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!

[@VintageEngineRepairs]

Thanks mate :) glad you enjoyed it!

[@KensSmallEngineRepair]

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!!

[@VintageEngineRepairs]

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!

[@paulmaxwell8851]

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!

[@VintageEngineRepairs]

Thanks for the kind words and your sub! I’m glad you enjoyed it :)

[@rc6392]

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.

[@VintageEngineRepairs]

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!

[@peterling2527]

Rivetting stuff! Beautifully explained and videoed, even my wife watched it! Many thanks

[@VintageEngineRepairs]

Very kind thank you!!

[@philliphall5198]

You really enjoy doing this and figuring out how to fix it I’m impressed with your skills and knowledge 😊😊😊

[@VintageEngineRepairs]

I do :) thanks for watching!

[@facereader99]

Came back to say that found this is the best video on the subject. Great! Thank you very much!

[@VintageEngineRepairs]

Ahh thanks mate :) I really appreciate it!

[@mattstubbington8805]

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.

[@VintageEngineRepairs]

That’s fantastic! Pleased for you :)

[@orlandobudoo4414]

I am very impressed with your knowledge of carburetors. The diagnosing of the problem and graphic illustrations are simply awesome. Thank you

[@VintageEngineRepairs]

Thank you! I really appreciate it!

[@choiceblade]

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.

[@VintageEngineRepairs]

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.

[@stefanpuszka2835]

Excellent description and execution of a tricky repair thanks for that insight.

[@VintageEngineRepairs]

Thank you for watching and commenting, I appreciate it :)

[@oldguy8177able]

man i've watched a lot of videos on this ,this is the first one that makes sense

[@VintageEngineRepairs]

That’s great :) glad you enjoyed it!

[@FarmCraft101]

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.

[@VintageEngineRepairs]

Hey :) great to see you over here, I love your content!

[@laverick12]

What a lovely video. So pleased that there are still people around that want to help others. Well done and thank you very much.

[@VintageEngineRepairs]

Thank you for the kind words :)

[@stevespencer9001]

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 🙏

[@stevespencer9001]

Update, got to the accelerator pump then lost it as the spring launched it into the garage somewhere 😂😂

[@VintageEngineRepairs]

Oh no 🤣

[@VintageEngineRepairs]

Not many know about it :) glad it helped!

[@MosoteX]

Nothing but EXCELLENCE! Thank you so much you saved me lots of frustrations and money! 🙏

[@VintageEngineRepairs]

Awesome! You’re welcome :)

[@mihaibarangamihai421]

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!

[@VintageEngineRepairs]

Fantastic! That’s great news :) keep me updated!

[@sandylee3609]

Thank you for the explanation of how to repair these carbs.

[@VintageEngineRepairs]

You’re welcome :)

[@TheJensen1996]

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.

[@VintageEngineRepairs]

All good mate, you’re welcome :) it was fun and it’s always good to meet people with similar interests!

[@julianbrearley6798]

Absolutely spot on! This fixed my MS 210C first go, thanks. Great tutorial with good diagram and clear verbal explanations.

[@VintageEngineRepairs]

Thank you :)

[@davidwatts6252]

Genius !!! Thankyou so much for this Video. I was going with your fix, but went with replacing the "O" ring, and it worked...Thankyou for GREAT Video.....

[@VintageEngineRepairs]

That’s a great choice to replace the o-ring when available, good call :)

[@bow3123]

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.

[@VintageEngineRepairs]

Good advise! I wasn’t sure if alcohol will dissolve nail polish, thanks for sharing g

[@stillman5733]

@@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...

[@alanwatt1981]

A master of your trade. Thank you for a real repair video!

[@VintageEngineRepairs]

You’re welcome, thanks for the kind words :)

[@samfletcher5023]

@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?

[@VintageEngineRepairs]

Thank you for your kind words :) I have videos on how they work and more coming out very shortly. Start with this one :) kzbin.info/www/bejne/lWWuZ5d4hrmYm80

[@freefallpilot]

EXACTLY the problem I had! So grateful for this video amigo 😊 thank you!

[@VintageEngineRepairs]

You’re welcome! :)

[@TLMD]

Like a pro! Great job brother! Keep up the awesome work!

[@VintageEngineRepairs]

Thanks mate :)

[@culturedredneckgarage3784]

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!

[@VintageEngineRepairs]

You’re welcome! If it’s an aftermarket Chinese clone, check everything inside it :)

[@sstocker31]

I've learned so much from your detailed videos, thanks for providing them to the tube!

[@VintageEngineRepairs]

You’re very welcome!!

[@brianlaird5355]

Thank you for the information. I like the way you took the time to go over the carb operation.

[@VintageEngineRepairs]

Thank you!

[@seanmchugh3476]

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.

[@VintageEngineRepairs]

Thanks for sharing! It could be your main nozzle!

[@notajp]

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.

[@VintageEngineRepairs]

I try my best to cover everything, but sometimes I’m on auto pilot.

[@hisanosukedyer]

Well, he had to adjust it again anyways because he had removed the adjustment screw so that he could thread in the throttle shaft and tighten up on the spring tension. Sometimes we need to try and figure out the finer details ourselves and be grateful to others for sharing the major details of their work experience in doing some stuff, whether it be mechanical or otherwise. Anyways, I worked on a Stihl weed eater and it would have cost $50 to ship a replacement carb over in a week to two.

[@suzanemartin8242]

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

[@VintageEngineRepairs]

Thank you! I’m glad you enjoyed the video and it made sense! Sometimes it can be hard to convey everything required :)

[@suzanemartin8242]

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 KZbin 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! 😎👍

[@VintageEngineRepairs]

@@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 :)

[@suzanemartin8242]

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.

[@stevenertle2876]

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

[@VintageEngineRepairs]

You’re very welcome! Glad you enjoyed it :)

[@kevwills858]

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 .. 👍🇦🇺

[@VintageEngineRepairs]

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!

[@thedahlins]

I've watched a number of your videos and I've found them extremely informative. As you may have guessed, I assumed you were British, but as I've watched other videos of yours, it seems you may be Australian. My apologies if I've got that wrong. Either way, I want to thank you for your in depth explanations of how things work. It's quite inspiring! I watched your video on rebuilding a Stihl 660 chainsaw. I wasn't able to find part 2 though, is that something you've had time to complete? Thank you for your hard work, all the best! Paul

[@VintageEngineRepairs]

Hey Paul, thanks for the kind words, I’m a Brit living in Australia lol. Yes there is a part 2, I believe it’s called “get more power”. If you look back through my recent videos it will be the first or second one after the video you watched :) hope this helps!

[@donlucas1631]

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.

[@VintageEngineRepairs]

The key is that they are nitrile or other petrol resistant material. If so and they fit, you’re good to go! :)

[@hisanosukedyer]

Thank you young Sir, for sharing this information with us, rather than taking this knowledge to the grave with you.👍👍👍

[@VintageEngineRepairs]

You’re very welcome!

[@garymcdonald6529]

So many of these armchair mechanics think the purge bulb is a primer bulb and will argue with you, they don’t know their arse from a hole in the ground. Very informative and well done video.

[@VintageEngineRepairs]

Yes indeed! Thanks for watching :)

[@BrucesShop]

Thanks Tom I am doing a Stihl bower this week. . Bruce from Canada.

[@VintageEngineRepairs]

Great stuff Bruce! The blower is in good hands with you!

[@louisianaq4192]

Lawn mowers as myself love y'all videos 🤜🏾🤛🏾 thanks my brother

[@VintageEngineRepairs]

Thanks mate!

[@kennethperian4370]

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.

[@VintageEngineRepairs]

Thanks for watching, pleased you enjoyed it 👍

[@kookiethebear]

Great job on the video and explanation! Another source of sucking air is a bad fuel tank cap o-ring.

[@VintageEngineRepairs]

Glad you enjoyed it! Yes they can, but fortunately that doesn’t affect fuel air ratio / how the engine runs :)

[@markmckenzie3072]

I've benefitted from a good number of your videos. Thanks very much indeed.

[@VintageEngineRepairs]

You’re welcome!

[@ringsidejudge4302]

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 .

[@VintageEngineRepairs]

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 - kzbin.info/www/bejne/g2fIiYJso52bnsksi=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.

[@ringsidejudge4302]

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

[@PatHaskell]

This is exactly the problem I am having with exactly the same carb!!!! How does YT know? Thanks for posting!

[@VintageEngineRepairs]

Crazy! Glad it helped :)

[@rickthelian2215]

Well done Tom, thanks for the technical information and hacks.😊

[@VintageEngineRepairs]

Pleasure Rick :)

[@ΙΩΑΝΝΗΣΚΕΤΙΚΟΓΛΟΥ]

This is the most useful video. Congratulations and thank you !!!!!

[@VintageEngineRepairs]

You’re very welcome!

[@adrianharu7503]

Having problem with mine as well. Thanks for that info

[@VintageEngineRepairs]

No problem 👍

[@thedahlins]

Brilliant! I see now why the British were able to develop the Merlin engine!

[@VintageEngineRepairs]

😂😂😂 that’s funny! Cheers mate :)

[@jonathaneves]

Must be satisfying to be so competent 😀

[@VintageEngineRepairs]

I always come across new things so it never feels that way haha

[@thedahlins]

Thank you, I'll check it out!

[@JCulpepper73]

Very well put together tutorial. Thank you sir!

[@VintageEngineRepairs]

Thank you!

[@mrih1586]

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.

[@VintageEngineRepairs]

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 👍👍

[@ras808]

Don't have this problem at the moment, nonetheless watched and admired the very clever diagnosis and resolution process.

[@VintageEngineRepairs]

Thank you :) much appreciated!

[@threejackcity4471]

your knowledge is truly impressive. thank you for a very informative video.

[@VintageEngineRepairs]

Thank you!

[@tinkeringtaylor3053]

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

[@VintageEngineRepairs]

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.

[@tinkeringtaylor3053]

@@VintageEngineRepairs you did very well on that one 👍👍

[@atcmadness4351]

I'd love to see you go thru a motorcycle 2 stroke and 4 stroke carb, although these little guys seem to be even more finicky to deal with. I take it all of these are purge bulbs, not primer bulbs like I've been calling them my entire life...

[@VintageEngineRepairs]

Hey, yes these are more complicated than motorcycle slide carbs, but neither are very difficult. I use to race a cr250 :) yes they are called purge bulbs, they purge the air from the carb, primers will shoot fuel into the intake.

[@briangordon1036]

Top job mate. If the accelerator pump can be disabled, why do they put there in the first place?

[@VintageEngineRepairs]

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!

[@ThePhilbox]

much appreciated! Rarely do people explain how it actually functions. I have a variation of this carb the keeps leaking fuel when i pump the bulb. Trying to understand why.

[@VintageEngineRepairs]

You’re welcome :) glad you enjoyed it!

[@davekosztan4641]

Very detailed video 👌👍

[@VintageEngineRepairs]

Thank you!

[@Big_Johns]

Great explanation Tom, thanks. 👍

[@VintageEngineRepairs]

Thanks John!

[@carlodonnell146]

Doesn't the vacuum from the piston/crankcase also play a part in getting fuel to the CARB. too?

[@VintageEngineRepairs]

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.

[@SHONEY21Z]

Maybe a dumb question, wouldn’t a replacement oring from an oring kit do the trick?

[@VintageEngineRepairs]

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!

[@danielgeng2306]

Exactly what I was looking for thanks for the tutorial!

[@VintageEngineRepairs]

Awesome! Glad it helped :)

[@mikenathaniel1521]

Thanks brother..that’s a thousand $$ repair

[@VintageEngineRepairs]

Glad the video helped 🤙🏻

[@stephensomersify]

Amazing detail - THANK YOU - old git, UK

[@VintageEngineRepairs]

Your welcome!!

[@rodgraff1782]

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.

[@VintageEngineRepairs]

You’re welcome and thanks for the kind words! Keep me posted

[@trainmaster0217]

Great video! Very nice explanation of the carb.

[@VintageEngineRepairs]

Thank you!

[@roseymalino9855]

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.

[@VintageEngineRepairs]

Interesting! So long as it’s not affecting anything you’re probably better to leave it, you may add a problem 🤣

[@bulldogms]

Really comprehensive. Thanks!

[@VintageEngineRepairs]

You’re welcome :)

[@jasonthurston799]

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!

[@VintageEngineRepairs]

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 :)

[@jasonthurston799]

@@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.... :).

[@VintageEngineRepairs]

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.

[@jasonthurston799]

@@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.

[@VintageEngineRepairs]

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 :)

[@tjxkeith]

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.

[@VintageEngineRepairs]

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 :)

[@Tactical_Arborist_1776]

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?

[@VintageEngineRepairs]

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 :)

[@JessieFrancis-kv5gq]

Dude. You are the man.

[@VintageEngineRepairs]

Haha thanks!

[@matthijsverweijmeren6114]

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?

[@VintageEngineRepairs]

Thank you :) yes they’re 3x1 mm 👍

[@jimbrewer2893]

Really good tutorial on operation.

[@VintageEngineRepairs]

Thank you :)

[@Kevinrichardsonministries]

Great Video... Great Camera Shots... Great All Around... You're a Master at Your Trade... Subscribed...

[@VintageEngineRepairs]

Thank you!!

[@robertmort5994]

In my case it's the check valve on the idle jet that's leaking air into the fuel. This problem rarely crops up it seems, but the location of this check valve isn't obvious, even in your otherwise clear video.

[@VintageEngineRepairs]

Yep! That’s only there for the purge system so if that leaks, it will let air into the bulb. Good find :)

[@alfredsamperi9776]

Thanks

[@VintageEngineRepairs]

Thank you for the super thanks! :) much appreciated!

[@nicholasjones7645]

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

[@VintageEngineRepairs]

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 :)

[@bobberglund5036]

So why didn’t you replace the O-ring?

[@VintageEngineRepairs]

Stihl don’t sell just the o-ring, you have to buy the plunger kit for $20.

[@dsim3211]

Thank you for sharing your knowledge! Very impressed and subscribed!

[@VintageEngineRepairs]

Thank you!

[@TheCC89]

So, what do you think caused the o ring to fail? Cheap fuel or dry rot from lack of use?

[@VintageEngineRepairs]

Na just age, it happens - it’s. wear item

[@frankqroosma2372]

Great video. Very thorough. That said, I will just purchase and replace the carb as I see a lot going wrong trying to rebuild.

[@VintageEngineRepairs]

That’s a shame, it’s not difficult :) give it a go!

[@bushratbeachbum]

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.

[@cliffordolivette3418]

Thanks for your knowledge

[@VintageEngineRepairs]

You’re welcome!

[@genewilson6262]

Great video man fixed my problem

[@VintageEngineRepairs]

Awesome!!

[@alanreynolds2125]

Help please! my strimmer purge valve depresses ok but stays down for a long time! after a few pumps starts to work ok! your thoughts please?

[@VintageEngineRepairs]

You have a blockage somewhere :)

[@alanreynolds2125]

god that was quick!! thank you, I think the tank filter is a good starting point and work back it is 25 years old after all! did put a kit in it 2 years ago and was working well at that time! cheers, Alan.@@VintageEngineRepairs

[@VintageEngineRepairs]

@alanreynolds2125 you’re welcome :) yep, start from the filter and work your way towards the bulb :) you’ll find it!

[@twintwo1429]

For a leaking check valve, the first thing to do is remove air filter housing. Look at intake / choke area of carb, and pump primer. If fuel is getting into carb at choke valve area and the machine is not running, and all connections are good, then you have a bad check valve. If your check valve is not replaceable, order another carburetor. For these types of carburetors, no need to remove or disassemble carb. Do check valve test first, if all hose connections and primer bulb is good. This saves time and effort with trouble shooting.

[@VintageEngineRepairs]

Hey! Sorry, I don’t understand? “If fuel is getting into carb at choke valve area”? How do you know if fuel is going through the check valve if the engine isn’t running? They’re under vacuum so they don’t leak.

[@twintwo1429]

@@VintageEngineRepairs if hose connections are good , machine is not running, throttle is not pulled, when you prime it, there should be no fuel getting into throat of carburetor. If there is, the main check valve will be leaking. Fuel should not be getting into throat of carburetor, unless it is being started or running. If you are not pulling cord and it's not running, then there is no pulse to pull fuel from carburetor.

[@VintageEngineRepairs]

@@twintwo1429 no that’s not right, the metering side of the carb is under vacuum, regardless of the check valve being open or closed it won’t leak.. imagine putting your thumb on the end of a straw the liquid is held inside. It’s the same principle here with the nozzel. The needle (which is your finger in the straw example) is holding the vacuum.

[@twintwo1429]

@@VintageEngineRepairs regardless of what you think, if the main check valve is bad, fuel will leak into throat of carburetor, when it shouldn't. Fuel should not be getting into throat of carburetor unless you pull cord or machine is running.

[@VintageEngineRepairs]

@@twintwo1429 again you’re wrong I’m afraid. How can fuel escape from a vacuum? If the needle is leaking and the check valve is too, THEN you’ll get leaking through the main nozzle, though also the idle drillings too… your explanation of diagnosis is flawed.