How to fix a string trimmer that won't prime (purge bulb doesn't work / won't fill) 

Thank you for showing us how to fix our line trimmer. Half an hour and she is running perfectly. Thank you from New Zealand the home of Do it yourself

Very helpful video. Good camera work, no wind or extraneous background noise, no annoying music, good and succinct info, everything i needed to understand why the minitiller wasn't priming. Not mine just helping out a friend. we both thank you so much!

RU-vidrs always spray the carburetor with solvent miraculously solves the problem. It never works that way for me.

funny i learned everything how to fix these and lawnmowers from youtube videos i enjoy fixing them it keeps me busy and its fun to see how they work and a sense of saticsfaction or achievment when you bring an old mower to life.

your mentor is happy with your progress Dave! keep up the good work!

Great job my STHIL trimmer started the first time THANK YOU!!

Thank you Dave you and donyboy73 are doing a awesome job helping people like myself tackling jobs like this 👍

Best video by far!! Thank you for not telling us 30 minutes of unnecessary info.. down to the problem!! Great job

I know you posted this over 2 years ago, but your video just helped me fix both my line trimmer and tree pole trimmer. Took about 45 minutes combined! Thank you so much for taking the time to explain in simple terms how to take care of this issue.

This video just walked me through fixing my Poulan Pro trimmer - I feel like an expert now, thank you!!!

3 year old video, and it helped with the exact problem I had. Thanks so much!

Never surrender! A simple bit of junk in one of the passages can make one wish they new tried to fix their carb, but a video like this encourages us to keep trying. Success is a wonderful thing!

I did exactly this for my stihl and it worked prefect after. Thank you for the video

Great video! I'm in the process of working this problem on a Fs 46c. So a big help!

Thank you so much for this. I was able to fix mine with the help of this video.

Hey thanks! Bought my first 2 stroke engine ever and had no idea how they worked, had the same issue as you and your solution fixed mine as well so thanks for taking the time to upload it.

awesome , detailed diagnosis. Thank you from Canada. I have a KM 55 Kombi - primer bulb will not fill, new carb kit as well. I am going to do the carb cleaner steps right now !

Had this issue happen while using my craftsman string trimmer on Friday. Took the carb apart and blew compress air to clear passages in carb and it fixed the concern. Thanks Dave great video!

Thanks so much for doing this video! This is exactly what I needed for my problem.

Thank you so much for this. I think I'll head out to my garage and see if I can get mine going now

Awesome. I followed your vid and it totally fixed my issue. I have the exact same trimmer. The FS38. This fix works!💪🏾🤘🏾👍🏾

thank you. pulling everything apart and cleaning now fills the bulb

That heled me sort mine out that has been sat for 6 months in the heat. Thank you!

Great video - quick and easy - especially for a dummy like me. Worked first time!!

Thank you for the viideo...really enjoyed it. but just to decrease worry of a pressurized tank. The primer bulb doesnt require pressure in tank. For fun, just try and prime your carb with the gas tank off. You will never have pressure in gas tank unless gas gets hot. Bear with me...here is a long winded explanation of the way the prime mechanism works. . The bulb is a pump. just like a well pump taking water out of a well. Pushing the bulb drives air or gas out the bulb into the longer outlet tube back to top of gas tank.... (not through the fuel filter). It purges at the level of the small black plastic connector at end of long outlet tube. There is a one way check valve in the plastic base under the bulb that prevents air from travelling from outlet tube back into the bulb (bubble). This allows a vacuum in the bubble. This opens up another one way check valve on bubble base to draw air from the top of the carburetor ( carb sits just under the bubble base). This subsequently draws fuel up the fuel filter tube into the side of carbutator. With every push of the bulb, the vacuum is restored and the cycle continues to draw more and more gas throughout the carburetor while pushing more air from the carburator into the bulb. This cycle continues onward until certain chambers of the carburetor become full and then gas stays in the bubble. This all depends on yet another one way valve on the gas inlet tube that doesn't allow gas to flow back into the fuel filter. Just like a water check valve doesn't allow water to flow from a house waterline back into a well. In this system, it keeps the gas inlet tube and subsequently the whole carburetor full of gas. If you have a bulb that doesnt move gas when you press it, then there is a leak or a blockage somewhere that prevents the vacumn from forming. So any leak in any tube or channel or sticking valve or faulty one way check valve or blocked channel will stop the whole process. And the issue could occur at any point from fuel filter, all the way through the carburetor, to the check valve on the air outlet tube. If you have this issue, it's best to soak the carburetor and bulb base (bulb removed) in mixed gas for a day if the carburetor has been sitting empty for a long time. Pray that it's just a leak in the bulb which is the easiest fix. If not, you have a real pain in the A$$ to work through.

Thats right super Dave!!, its a "purge bulb" ,so glad to hear you recognize it as so!

Thank you sir. This worked flawlessly

Thank you that video was very helpful I appreciate it.there's a lot of videos out there that are too long and don't get to the point right away .you wasted no time getting to the problem thank you excellent video⭐⭐⭐⭐⭐ ,,✌🇺🇸

We got a weed eater that had not started in 7 yrs running with the help of this video! Thank you.

Thank you Dave for the great job in cleaning the carburetor.I'll have to do the same with by my Stihl trimmer FS 311 because I believe the carburator has clogged because it hasn't been used for a year and the the gasoline is old and filthy.Thank you from Umbria in Italy.

Great Job Dave! Keep up the great work and videos buddy!!

Hey mate, Best video I have ever used. So easy to follow and fix something I wouldn’t have touched. If you’re ever in Australia I will buy you a beer .

Thanks alot. I followed your video and mines is back to normal. 👍🏽I have the fs55.

This was a huge help, thank you!

I can vouch for this video. Replaced the fuel lines, filters and primer bulb on a Husqvarna trimmer but still wouldnt prime afterwards. Came in to see if there was something silly I missed and came back to a bulb full of fuel. Sat in the garage for too long I guess. Just watching the video was enough to fix it! :-)

Watched your Vid and it worked great. I had the same issue, started second pull! Thanks for sharing!

Nice and informative video Dave keep on doing them.

This had help me a lot was having this same problem I'm going too try it for myself Thanks

Thankyou same problem and good to see help us to give it a go

Followed your instructions and solved my problem. New subscriber.

Thanks for helping me figure why my KM55 R was not priming. (Watching from Barbados)

Many thanks for the informative demo. I had a problem with purge (primer) bulb not filling on my Stihl HS85 hedge trimmer. Slightly different components, but cleaned out the carb with WD40, and now it's working a treat again.

This cleared up a few things for me too, thanks for the great video!

Great Video man !! Cleared up a lot of questions. Thanks. Keep them coming !

Wow. I'm very impressed and can't wait to try this when I get home! Thank you. I was having the same problem.

Thank you for your time showing this repair. I found you do the videos with Donyboy 73.

this taught me nothing about my Milwaukee cordless trimmer but watched anyways lol. Cool videos your doing Dave!

Thank you for sharing this! I have same problem with my stihl since brand new

Great video and description!

Thanks for the info. I wasn't aware that the primer bulb actually pressurized the fuel tank,which pushes the fuel up to the carburator,then thru the bulb & the excess returns to the tank.I know that on some 4 stroke small engines.the primer bulb pressurizes the carburator bowl,which in turn forces some fuel into the intake throat. Thank you for this Great video

Good fix with very good detail and closeups!! Thanks for sharing your knowledge. I’m trying to learn all I can. There are no longer any small engine classes here locally so good videos like this really helps me learn. Thank you Dave!👍

Solved my annoying problem today cheers from australia

Thank you so much for the video! It was very helpful!

Thank you, this video was all I needed.

Spot on, good info and explanations , Thank You 😊

Great video. Learned a lot.

Got mine running! Much thanks!!

Your video and how you explain and show it is nothing short of awesome. I had the exact problem on the same model and followed your instructions and got the same outcome ... it runs again! Thanks again, you had good video work and the explanation was perfect ... not too little, not too much info. I'm subscribed!

Cheers from Aussie 👍

Great video start to finish , explaining, picture , all good , didn't try to make a t.v. show out of it and most important to show us that it don't work and the difference he made in making it work , job well done , didn't waste no time at all , VIDEO IS A GREAT EXAPLE !!!! What u-tube is suppose to be about......

Many thanks, mine now starts and runs well. Liked and subscribed.

Nice job on the video. I’ll give that a try.

Nice vid Dave. Stihl is great and easy to get parts for.

Nice video all step by step good job man

Thanks Dave - excellent video. Off to tackle my FS-91. Cheers, mb from New South Wales, Australia.

Your video was very helpful thank you. You explained it very well.

Thanks mate, big help 👍

Very good work. Thanks.

Awesome video,stay safe

great job diagnosing .....thumbs up

Thank you so much for this video! I had tried to start my stihl and had forgotten to pump it first. Then when I pumped it nothing came. So, I came to youtube to find a video like yours and when you explained about releasing pressure from the tank I went and di it and then started pumping. It worked and I was able to cut my grass and didn.t have to go and find a mechanic! Thanks so much

Great video... We'll made and everything is explained well. Thanks, it helped me

Great video Dave well done

Just the video I needed...thanks!

Thank you for your help

Love the video you make real simple to work on this small engine congrats my friend ernie from Miami

This vid helpd big time n i saved a lot

Awesome video! I had the same problem with my 17year old STIHL FS-46C trimmer and I initially thought it was a bad primer bulb or faulty fuel line. After replacing those, I still had very little to no prime. Before buying a replacement carburetor I decided to take the original carburetor apart and clean it out with compressed air and carb cleaner and just like that the primer bulb fills completely and the trimmer starts right up and runs great. Thanks so much!!

It’s a skill that is not going to be around much longer. This video will help someone out years from now if it’s still here.

Great vid Dave nice explanation

Thanks for the timely video Dave ! My STIHL leaf blower has the same symptoms. I'll give your advice a whirl. Your channel is really coming along nicely. Always enjoy watching !

Very helpful. Thank you!

Exact same carb on my Stihl garden tiller. Exact same problem too. Now I think I can fix it. Thanks!

This is exactly the video I needed. I just replaced the primer bulb and now it's not priming. Unfortunately none of the 3 8mm sockets I have will fit between the plastic surrounding the nuts and I now have to go and buy a 4th slimmer socket😢🙄

I love the Stihl machines nice n machines . Great video.

Thanks for the videos Dave, have a Echo srm 2100 that the primer bulb wasn't working. looks like almost the same carb, followed along with your vid. After cleaning carb, started first pull.

thanks for taking the time to do this vid mate. I had this exact prob and followed your instructions and problem solved. Now just have to work out why it starts and runs for a few seconds and the dies! cheers from Australia.

Thank you! Perfect!

awesome , need to take mine apart to clean the carb

Great vid, very informative

Very interesting video, thanks Dave!

Excellent video, nice job. Fixed my Stihl HL 45 hedge trimmer using your video. It primes, starts, and idles now. I'm with Ethan (below), on some "fine tuning" help. Mine runs good but bogs a bit on acceleration, and I can't seem to "fine tune" it to get rid of the bog.

Thank you so much.

Nice job. Thanks for sharing.

Cool. I'm gonna be fixing a craftsman trimmer I subscribed I'll keep checking for info. Thanks man

Great job 👍

I can’t believe i have the same stihi, same problem even ran ok last summer. I dismantled cleaned and blew it out. Wouldn’t pump fuel. Have coffee with youtube search. Yours came up 1st. Nah doubt it but I’ll try the carb cleaner. Yes, worked like a charm first pull.

The primer bulb does not pressurize the fuel tank. It doesn't have enough volume to create much pressure. You can debunk this by starting the trimmer with the fuel cap off and it will run fine. When the primer bulb is pressed it sucks a small amount of fuel into the carby from the bottom line. Any excess is returned back to the tank via the top fuel line.

That my friend is just what the doctor ordered! 100% my problem and the fix. No messin' around followed Dave's instructions and I'm good to go!! Thanks Dave. Now you just need to post carb dissasembly / clean up for a Honda lawn mower. Stay safe!!

Another great video for DIYers. Probably remove the needle before spraying cleaner in the passage, some products can deform or melt the tip of the needle. better safe than sorry.