HOW-TO Pressure Test A 2 Cycle Carburetor

HOW-TO Pressure Test A 2 Cycle Carburetor
In this video I show you how to pressure test a 2 cycle carburetor to determine the integrity of the needle valve in it.
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Easy to follow and thorough step by step tutorials do it yourself (DIY) videos to help you with your broken lawn and garden equipment including snowblowers.
I do my best to teach you how to easily diagnose problems the fastest, quickest and most efficient way with real repairs beyond just replacing a spark plug. These tips are for both the homeowner and shop owner.
Whether it be a handheld, two stroke, two cycle engine like a chainsaw, weed eater, weed wacker, string trimmer, grass trimmer, line trimmer, hedge trimmer, strimmer, brush cutter, leaf blower, or four stroke, four cycle units like a lawnmower, wood splitter, lawn tractor, zero turn mower, snowblower, pressure washer, generator or a ride on mower that needs parts installed or replaced, I’m your go-to guy.
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I’ve been a small engine mechanic for many decades and also run my own repair shop so my videos are loaded with tips and tricks that I have learned and want to share with you. You will also find many tool and product reviews from top brands on my channel as well.
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Due to factors beyond the control of DONYBOY73 “The Small Engine Doctor”, it cannot guarantee against unauthorized modifications of this information, or improper use of this information. DONYBOY73 “The Small Engine Doctor” assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. DONYBOY73 “The Small Engine Doctor” recommends safe practices when working with power tools, hand tools, lifting tools, jack stands, electrical equipment, blunt instruments, chemicals, lubricants, or any other tools or equipment seen or implied in this video. Due to factors beyond the control of DONYBOY73 “The Small Engine Doctor”, no information contained in this video shall create any express or implied warranty or guarantee of any particular result. Any injury, damage or loss that may result from improper use of these tools, equipment, or the information contained in this video is the sole responsibility of the user and not DONYBOY73 “The Small Engine Doctor".
#donyboy73 #smallengine #carburetor

[@mebcool]

Thanks Donyboy 73 I really appreciate your mild mannered personality. Keep up the great work sir.

[@jawnjw]

Learn something new from you all the time I had no ideal you could pressure test a carb thanks

[@donens9310]

Donyboy; have Husq 266 with Tillotson hs254b. My tester shows inHg and mmHg. Any idea on what the 7 psi should be on my tester? Also, what does it mean if the pressure test goes up, then very slowly goes down and settles to a spot, then stays there with no further decrease?

[@EHS603]

I always learn something from watching your channel. Thanks.

[@hiphopman72]

Solid video

[@donyboy73]

thanks

[@user-gi3xj8nz3s]

Where can I get a pressure tester like yours. Do you have a link ?

[@donyboy73]

email me at [e-mail]. i have a similar one left

[@michaelchilders6056]

Thank you again Don. I’m trying to learn all I can about small engines and your videos never fail.👍👍

[@williammoore5924]

GM to Sir. It’s always a pleasure to listen and watch your informative videos. Keep them coming. Ordering a pressure tester today. Later Dony

[@geojor]

very practical info Dony !

[@alanlake5220]

Where did you get the pressure tester from, and what is the part no, great vid by the way

[@waltercooling8907]

Make your own-it's easy and cheap

[@sunilsenevirathne4245]

Thank you sir appreciated your kind experlation hope you will give more creations in future

[@tacx1]

@@waltercooling8907 ok, are you going to share this info ???

[@zx8401ztv]

Smashing test :-D It's too easy to forget testing information over the years if it's a once in a blue moon problem. Lucky for us, a loverly chap called Don has made lots of help videos over the years :-D. Thankyou for all your videos Don, the live version of the haynes workshop manual, with tricks and valuable tips :-D

[@donyboy73]

thanks man

[@spelunkerd]

Well stated, I feel the same way.

[@pm270100]

i been here for 5 years don is the best

[@zx8401ztv]

I do think don is a live version of the haynes repair manual, if you don't have the tool he will show you another way :-D

[@terracewaggoner6412]

I have a 280 cc 2 stroke engine with a Walbro WB Carb. The carb on the unit came with a PSI popoff pressure of 11 PSI. The company says the pop-off pressure should be 17-19 PSI. How do you calibrate the Popoff pressure making it 17-19 PSI. Thanks in advance for your assistance.

[@Jack.of.all.learning]

As always, great video. Your tone and presentation is 👍👍

[@comet7894]

Didn't the bad carburetor fail the test because of bad check valves rather than diaphram/gasket?

[@mohabatkhanmalak1161]

I have some old 1950's small engines and we also have lawn care machines at home. These videos will come in handy. Thank you and thumbs up.

[@rpavlik1]

That was a great video - really good to have this kind of general, fundamentals content. Works even if I don't have a Stihl chainsaw 😄

[@jorgeortega1709]

Do you have a link where you can get that tester?

[@Reparatour]

Google for: CARBURETOR PRESSURE TESTER GAUGE

[@franklinkopecky9644]

search for walbro pressure tester

[@franklinkopecky9644]

amazon or ebay... they are about 30 or 40 bucks

[@christopherjuarez7039]

I searched and kept getting different products. Try searching for "pop off pressure guage" and it should help.

[@viewer54322]

I bought a mityvac radiator pressure tester online, it is a hand pump w/ gauge. Cost is nearly the same as the carb pressure testers but you also get radiator cap adapters that fit most vehicles. Be aware that there is another mityvac that looks similar but it only is for creating vacuum and doesn't come with caps. They also carry one called the silver edition which can do both vacuum and pressure I believe. The pressure tester that dony is using is durable, lighter and smaller but that may not be important to you if you aren't using it daily as he does.

[@rverro8478]

There is not, pressure tester, big enough, to test my Ex ...Too many leaks...

[@waltercooling8907]

Dony, be sure to add the info about diapham flexability and post height- it can bleed off pressure because it will depress the lever. Make sure the lever arm is at proper height in relation to the carb body

[@nashguy207]

Donyboy great educational video. Very helpful for a lot of people. Have a great day. God Bless!!!

[@jim21804]

Great video. I always learn something new watching your videos. Of course, by following your videos on how to properly care for my equipment allows me to avoid a lot of the repairs you show in your other videos!!!!!

[@wysetech2000]

Your video's just keep getting better.

[@Treestouch]

Thank you for this film, it has helped me further diagnose and repair my equipment🙏

[@mikeshoenberger]

Do you have the part number for the pressure tester.

[@robbeaupre8110]

Dony, you have the best videos on KZbin! Good timing as I was considering this kind of pressure tester vs the Mityvac MIT8500. I just ordered the Mityvac because I believe I can use it for bleeding the brakes on my ATV. Can you confirm I can use the Mityvac to do these tests in your video as well. I have seen other vids so I'm pretty sure I can.

[@donyboy73]

yes u can

[@RBAERO]

Nice video. I have many engines with different cc's, 50cc rc engine, 70cc hacksaw, 20cc and others most with Walbro Carbs. How I know or calculate the right pressure for each engine/carburetors?

[@reganmccutcheon8616]

We also do a vacuum test and it indicates if check valves are working, should hold pressure and vacuum if not carb should be replaced not rebuilt

[@paulroosa9932]

PR DESIGNS This should be everyone's go to spot for information on small engines! I have always found the info and processes I needed for keeping my engines running properly. Donny Boy is concise and obviously knows his stuff....NO bull**** from him!!! I do have a question I was hoping someone could help me answer though......I have a Walbro off of a 031 and a Tillotson off of a 041. I have put complete rebuild kits in both and no matter what I do I get a leak down on the pump side. I know the needle/seat are good as I have tested it with that side open under water and the seat doesn't bubble. is there a tip for sealing up those flexible valves and gaskets on the pump side even with all new parts?? Should i just try running it before buying new carbs?? Thanks DonnyBoy and anyone else who can help

[@dennishall7422]

Very handy information, Great test equipment that we had decades ago.

[@andrewsteele7663]

Thanks Don, love your tutorials, I have subscribed and look forward to all that you post, I have learnt so much that I have serviced all my small engines,, successfully, cheers and hello from Queensland

[@johnlanzatella4226]

You are the best! Came across your vids when I had a short in my Craftsman tractor. You are a wealth of knowledge without the lame " acting" that a lot of others make the viewer go through. And your always spot on. Not just guessing like many others. Thank you!

[@haroonurrashid6837]

بھائی میں میکنیک کام کرتاہے بہت پربلم کاربر ٹر سمجھ نہیں اتا ہے تکھ جا تا ہے مسلہ کار بیر ٹر کا حل نہیں ہو تا ہے ابھی میری 2 chainsaw ہے یہ مسلہ still 210 دوسر مکیتہ dcs34 ہے 20 دن سے لگا ھو تاہے ٹیھک نہیں ہوا

[@adkfoothills1973]

Very informative and helpful videos, Donyboy. Thank you, you have definitely made a difference. 🙂🙂

[@DavidMartin-wq5pn]

Great vid. Looking for a replacement carb for a 1975 lawnboy, any suggestions?

[@donyboy73]

check ebay

[@battlehrfred]

excellent information and ty for explaaining 100--100 video !! BTW were did you buy thid pump, or where did you buy the pieces to make this pump, excellent ty

[@jessemixon5764]

Thank you Don, for sharing your years knowledge with others I appreciate it- I'm learning that you just can't always clean and put a kit in a carburetor and it work properly- it also seems to make a difference to put back original equipment quality parts when repairing equipment and sometimes it's best to put a new part back in it as opposed to rebuilding the old one

[@butler386]

Excellent video. I may have to get a tester.

[@Contractorrepair]

Donnie where did you get the pressure tester from could you just reply and send the link

[@donyboy73]

got it years ago from an oem supplier, I will post a set I am selling later today on Instagram and facebook donyboy73

[@Contractorrepair]

@@donyboy73 Thanks .

[@germancarfan]

Google 'CTS leak detector'

[@welostourdemocracy]

The inlet side of the carb, is that the diaphragm side or the reed valve side? What is the best way to know for certain you're putting air in the correct tube of the carb to check the seat valve? The weed eater I'm working on, Poulan Pro 335, did not have gas lines on it.

[@kelvinpen3144]

Can I use this type of carb pressure tester also for testing chainsaw crankcase pressure ? Or do I need a different one such as the mityvac8500 Thx

[@donyboy73]

better with the mityvac

[@kelvinpen3144]

@@donyboy73 Thanks I was hoping to do two testing jobs with one tool ?

[@98306]

Thank You Don for the valuable information. Can you please give more information on the Tool that is being used and where to buy

[@sethhaun4440]

Nice appoligize' had to turn of my notifications and not check them do to a ll the non beleiver.s in god.but i always support ..ya..have blessed day ..forgot to tell Dave ..I bragged on him at are 3 shops here in tn...they got jealous

[@smartcrow7630]

Hi Don, Can you tell me where to buy a pressure gauge system like yours? Thank You, nice video!! =KL=

[@donyboy73]

what's your email?

[@jcssmallenginerepair3261]

Hey Don, so what do you do when you have a two-cycle carb with a primer and it passed all leak tests but will not pull fuel when priming?

[@RBAERO]

How we change the pop-off pressure on walbro carbs?

[@camreed7073]

very very good video Danny thank you for the lessen

[@kd5dvmkatdaddie114]

Thank you Don. You write straight with crooked lines. That means you always give me a new insight how to perform OPE testing a little better, quicker and good logic with inputs and outputs and what to check next.You're the best.

[@rogeliopadilla1432]

Thank you very very muuuuuuch..!! Great video and tips. Godbless..!! 🙋‍♂️

[@larrys8086]

dony..thanks for all the great info but as a rookie I have a question. Is there a rule of thumb as to how to identify the intake from the impulse ?

[@bernardviau1795]

Dony, you are a born teacher...

[@donyboy73]

i love to teach! i'm not here just for subs

[@tonym6920]

Great demonstration Dony!

[@dennisjoiner3717]

As usual I enjoy your videos. I do have a question. I have had one of those pressure testers for many years, but it's time for a rebuild. Do you have any idea if there is a rebuild kit available for it, and if so where to get one?

[@donyboy73]

no rebuild kit, Stens has a good tester

[@mattmaxon7783]

I don't have one of these but I'd wager just looking at it, there are a couple o-rings that are easily available that need to be replaced, how to get that bad boy apart is a good question

[@TH-cl5be]

hello if i squirt brake cleaner in the fuel entry point it comes straight out the return pipe part is my needle not seated ?

[@arthurfricchione8119]

Don’t as usual another good video. Thanks for sharing your knowledge. Have a good one. 👍👍👍

[@billk5727]

Great video and explanations with tips! Thanks man! TakeCare, Bill

[@GrampiesWorkshop]

How's she goin'? Some great tips here Dony. Thanks a lot for sharing!!! Take care!!!

[@BrucesShop]

Thanks Don. You are the 2 stroke MAN

[@davidsaltz5708]

Where can I find the pressure tester?what tester costs?

[@lukepodolski8818]

How do you fix when you pressure test carb and you have a leak from air valve screws?

[@donyboy73]

i replace diaphragm gasket

[@lukepodolski8818]

@@donyboy73 I got a solo 651 chainsaw and the carb is leaking from the high and low air valve screws. How would you fix that?

[@donyboy73]

@@lukepodolski8818 sometimes clear nail polish works on the outside of threads

[@lukepodolski8818]

@@donyboy73 thank you: ill give it a try

[@bigbob0042]

Great Video Dony

[@calvinmientke3539]

XCLNT ! Another video to make me look smarter. Thanks! CM

[@robertsimard735]

Great video. Thanks for sharing.

[@CFProton]

Can you overpressure a carb and damage the seals? Thanks for another great self help video.

[@christopherjuarez7039]

Yes, you don't want to go over 7 or 10 psi but don't quote me on it do some research if you're gonna buy the tool.

[@donyboy73]

yes u can, don't go over 10

[@philliphall5198]

I preprime them and then test, it just takes a second to do it 😊

[@cal48koho]

very well explained PROFESSOR devoid of the nonsense and stupid music so prevalent on youtube. I rarely subscribe but you are the exception. Where are you located? Where can I get the pressure tester?

[@donyboy73]

thanks Hugh, you can get it from online or small engine shop that is a stens dealer

[@Saw_Squatch]

Should a carb hold any kind of vacuum?

[@robertchaffee5662]

Do you have a link to that pressure tester?

[@jimmypopp2695]

Hey Don, Thank you for this video! I am gearing up to start a mobile small engine/equipment repair/welding business in PA and I saw you on the Small engine Nation with Fill and am learning all I can about two cycle engines. I raced a KXT250 Tecate in the 90's but things never stay exactly the same. Where are you located my friend?

[@donyboy73]

congrats on your new business, I'm in Ontario Canada. I'm also a bike rider too!

[@jimmypopp2695]

@@donyboy73 Thank you Dony. I am thinking abut doing free pickup and delivery for equipment and here is why. I have a place to do the work but it is at a relative's and I cannot have customers coming and going.within reason I would pickup and deliver anything all the way down to a chainsaw. I know this wil modify itself as I get more business. thank you again. love the vids.

[@mecanica2tempososcarmotors68]

Olá gostei do seu vídeo, onde posso adquirir uma ferramenta como essa?

[@robertchaffee5662]

Very informative! Great job!

[@mafosa8519]

Where did you get that tester? Larry

[@BearE9090]

Great tip for removing pressure from the line.

[@GHULAMABBAS-bs4hy]

Dear bother wear your service Cantor

[@janparolek2728]

Hi, where can I buy a pressure tester? or under what name can be found? Thank you!

[@donyboy73]

i have one left for 79.99, the one in video is over $150, just email me at [e-mail] and I'll send you pics

[@mattmaxon7783]

The Stens 705-020 is available widely, though the Mityvac MV8500 is probably a better choice since it will do Vacuum & pressure tests as well as help bleed brakes on your car etc... at the same-ish price. If you're doing pressure tests all day long it's probably better to have a dedicated tool, if you are a home owner semi-pro user the multi-purpose Mityvac might be the way to go

[@germancarfan]

Google 'CTS leak detector'

[@charlesbakes2855]

Why don't you put the part numbers of the tools that you use and we can purchase the ones that you use that would be very beneficial thanks very beneficial thank you very much

[@donyboy73]

kzbin.info/www/bejne/q4imm6GKpsuLg5o

[@BuildBreakFix]

I Guess 7 is The Lucky Number!

[@dtjones17]

where did you get that hand pump?

[@splash5974]

Thank you Always showing us great tips!

[@Dmax04]

Very informative. Thank you. Just rebuilt a HDC 44 on a Homelite Super E-Z. Leaks around the gaskets and won't hold any pressure. So far I've been unable to locate another carb.

[@marknye51.thefixitguy]

I don't have that pressure tester. Where can I buy one and what is it's actual name and brand. Thanks Dony

[@mikefisc9989]

Walbro 57-21-1. Price varies from $125.00 to $180.00 USD or more depending on where it is in stock.

[@stevenandrews6627]

Very helpful. Great post.

[@johnclarke6647]

What you really have to look at, today, is - is the carb plumbed correctly. I picked up a little MAC saw a few weeks ago and the idiot that had owned it, previously, had plumbed it up all wrong. The fuel line was plugged into the carb and not the primer bulb and the overflow line was plugged into the carb. New fuel lines and diaphragms correct the running problems of this saw. When I doubt concerning the fuel lines I always consult an IPLfor the specific model of saw i am working on. The little Mac not starts with one pull and runs fine. I did pressure test it with my Mighty Vac to 7#.

[@henrikjonsson4340]

Thanks It what theydo with car engines but with smoke. Can you do that here too? I have done almost everything but still can not get it running. I have sprayed into the channels, changed the diagphram but not the gaskets because it looked good. It is also good to look over the other externely gaskets after the carburator into the combustion chamber. Any leaks will be disastres to the mashine. Look all the way.

[@rltkktlr]

Nice video. Can you put a link for that pressure tester please.

[@jdimeo1966]

Yes, I would like that as well.

[@ADA5611]

Hey Don thanks for VIDEO on pressure testing 2 cycle carburetors. I have a BVM200VS poulan pro leaf blower. Installed new carburetor can't get it run. Have any suggestions.

[@mikelikos6471]

What causes a primer bulb to stay down & not pop back up when pushed????

[@donyboy73]

sometimes a bad carb kit

[@robertmailhos8159]

Great job with that one my Canadian brother 😀 😀

[@ivandrrccoffie7734]

Where can i get a tester like that. Prt nr please.

[@RussellBooth1977]

I did the Mason jar test on a carburetor which wasn't that old,I applied a small amount of compressed air to the inlet & I had the carburetor submersed in water. What do you know? air bubbles appeared around the main nozzles check valve,it was badly assembled at the factory. The check valve was Loctited in & the fuel had eaten away the Loctite,I'd like to know who made it but it was crap,fuel was leaking from around the check valve. I've never had that problem with the $16 AUD Chinese carburetors,so I don't know who made it. I bought another $30 AUD carburetor locally (in Australia) & it ran the hedge trimmer no problems & no returns !

[@Mr3Charlie]

Great information! Thank you!

[@JM-yx1lm]

I dont understand why people waste time telling us the part number of whatever they are working on. Who on earth would buy a part just because it looks similar to the one in the video?

[@charlythouvenot1746]

Hi Dony, excellent vid' from you as always, but, you don't test the pop-off pressure? Isn't it an important thing to check with those testers? I've learned on an rc website that it should be at 0.8bar Hi from France

[@theone9564]

Hello sir! I got a stihl 015l chainsaw. Rebuilt carburetor however it turns s on stays on with throttle. H is all the was down but when I start to open it chainsaw turns off. Any ideas.

[@swordfish1120]

What purpose does that hole on the carb cover plate serve? Will a Mityvac that has a pressure pump feature work the same as the pump you are using?

[@eldigitom9680]

That was a fantastic video, and VERY thorough...thx!

[@anthonygostling]

Not many will go out and buy a pressure tester, they cost a lot...!

[@PedroRodriguez-he1ou]

Hi how can i make one of those pressure tester or where can i buy one. Thank you for the information you share

[@MrTurbo64]

Sometimes just a small adjustment of the needle valve lever is all it takes to get that weedeater running again. Pry it up ever so slightly and make sure needle valve moves freely and try again.

[@AllanLaal]

@donyboy73 what if the pressure drops over minutes?

[@burtpilon1735]

Great video thx for sharing. Can I get the part # for brass hose adaptor that you have hooked up to use with different size fuel lines. I’ve never seen that particular one Thx