From ZAMA carburetor website: Pop-off pressure: "A lot of emphasis has been placed on carburetor pop-off pressures when in reality they are not an important issue to the service professional. In fact checking pop-off pressure can often damage the carburetor by stretching the fuel pump diaphragm and breaking the seal of the fuel pump gasket. Rather than pressurizing the carburetor to pop-off, Zama recommends that the carburetor should be pressurized at the fuel fitting to 10 p.s.i. It should hold this pressure for a minimum of 15 seconds."
Louie and Don, Well done! My boyfriend and I had to get that boggy old Ryobi gas weed trimmer going, and after watching your video, we learned a lot, especially about fuel delivery. It runs fine, as my sore arm will attest, the lawn is done- and now maybe we can figure out the carb problem on the high-wheel weed trimmer.
Walbro makes excellent small engine Carbs. My 2006 Echo CS 330T has always run perfect, but past few times, it started acting like running out of fuel, Now it will not start. New Walbro carb kit fix is on the way
It drives me crazy when people always call the purge bulb a primer on 2 cycle equipment! All it does is confuses people who don’t actually know how these fuel management systems work now days. The (purge bulb/bubble) is not actually a primer bulb as they used to be years ago on equipment. You do still see a lot of 4 cycle equipment with actual primer bulbs that literally squirt fuel into the intake when actuated, however the carburetors in this video and on most of today’s modern 2 cycle equipment is actually a Purge bulb meaning it has 2 lines going to the fuel tank one feeding it, one a return. When you press the bulb it just circulates the fuel though the carburetor ridding any air that might be trapped in the lines or the carb. I used to work on small engines on a mass production level and you would not believe the amount of units I had come in with no start as the complaint and all it would be was the owner operator thought if they actually pushed the bulb more than once or twice they would flood the engine! If you don’t use it the purge bulb the equipment is hard to start. 😂 I wish we could all just stick to calling it a purge bulb and explain the simple fact that it’s not like a carb on a car that you can flood the engine with. You can press the bulb till your pink in the face and it won’t flood anything 😆
So what you're explaining is. When you push the purge bulb it pushes fuel through the carb to pass any air into tank and introducing fuel,essentially priming it. Lol
I was excited when I saw your 57-11 pressure tester. Then I looked it up and saw the $158.00 price. Wow! But thanks for the informative video. And for everyone out there, as another commenter said- primer bulbs dont prime, they purge. You can press them 100 times and you will not flood the carb. They only purge the carb of air. Cheers.
Come one man, you got 5+ search engines at your disposal, use the modern resources at your disposal and buy the right thing for you. Its not like walbro invented a pressure gauge and pump.
@@em4703 Funny! The problem these days is where to find a good tester (or any tool) from other sources that isn't a Chinese knockoff. If you have a good tester that isn't $158.00 you would benefit me and others to share that information. I would do the same.
No mention of the purpose of two throats on the WYA carburetor, and the lack of any adjustment screws whatsoever. Excellent video. I attended a training class for Stihl products when I worked for a dealership and your video covers a lot of the same material.
Second passage is generally indicative of a "strato"-scavenged engine. One passage for mix of fuel/air, other for air-only. Typically the air-only is controlled by a separate throttle-body feeding into two transfer ports, separate from the carb, with linkage between. Then there are AutoTune carbs, with no adjustment screws for H or L mixture or idle throttle position.
there attempt at make carbs more efficent and they have special feature/ drains fuel back to tank after 2 hrs.. so self storage itself! pros and cons ... they do save on fuel and stay running longer without a clean ! cons .. they get dirty and alot more parts and they seem tempermental as they age / like starts harder and irregular ! they all got safety caps on needles and always takes 2 or 3 different screwdrivers to work on them ! seem too say Fu + chit alot when strips my 20 tooth screwdriver! from china! oh yea....
Video veramente bello, parlo solo in Italiano o un poco in Francese quindi non capisco le spiegazioni, ma le immagini sono chiarissimo. Professionalità, Serietà, Precisione, Qualità. Congratulazioni, Ottimo!
I've re-built these a few times, it really works. The carbs are damaged by ethanol, even if you use a stabilizer. Note: Only use marine grade Stabil. The red stuff isn't good enough. It's mostly the metering diaphragm that goes bad and causes your engine not to start.
Thanks for a great video guys. I do have a concern about the tamper resistant section though. If all the carburetors you guys produce operated at the same air temperature and same elevation above the same mean sea level @ a specific barometric pressure you would not have an H/L adjustment on your product. In my real world it simply ain't so. I have had to make adjustments on the fly just to get through the day on mountain side harvesting. I know what we really need to do is keep congress out of the engineering department. If you don’t believe it just look what happened to our gas cans!!! Thanks Ray n S.C.
after doing EXTENSIVE research, the only state that law applies in is California; besides that EPA states you just have to adust it in regulation. NO LAW STATING ANYTHING about athorized dealer crap.
And if you want to really fine tune your trimmer/blower/chainsaw engine they need to be tweaked every time you remix a jug of gas/oil. As precise as I try to put exactly 2.6oz of oil in 1 gallon of gas, it's never the same each time. The problem is compounded with carbs with no mixture adjustments. And in the time it took to write this 10 politicians took off in a chartered jet.
@@mrgrumpy5116 I fear the day when they go after NASCAR, the NHRA/IHRA, etc. Or they tax them so heavily that we end up paying $200 for a spectator ticket to a dragrace.
Great Video, I saw where you put a drop of oil on the impulse passage to see the oil move. I would like to put a gauge on the impulse tube to measure the actual pressure and vacuum. What would be the minimum measurements to properly operate the fuel pump diaphragm on a HD 12-1 carburetor. Thank You
Very informative video. A lot of people mistakenly call the air purge bulb a “primer bulb”. Some older lawn mowers and snow blowers did have an actual primer bulb that forced fuel into the throat of the carb.In this application though it just pulls fuel from the tank, circulates it through the carb,then returns it to the tank to eliminate air from the system to ease starting. Generally, if there is also a choke lever it is an air purge not a primer.
If you look into the throat of the carb while pumping the bulb and you observe fuel squirting inside then that action is priming the carb. All this talk about "purging" is incorrect in my opinion. The primer bulb has valves which are oriented so one pulls or creates a vacuum FROM the carb and other pumps or pushes unused fuel back fuel into the tank (the return line). Once the air in the system is mostly displaced by fuel then the primer is pulling fuel into the carb. The vacuum created pulls fuel from the tank up into the opposite side of the carb, effectively priming the carb. If you think the primer is just purging air then please explain in detail how that differs from what I've just described. In my opinion the ultimate action of the primer bulb is actually priming the carb, NOT purging air, although purging the air is a prerequisite and first action for pulling fuel into the carb. At any rate, I'll continue to refer to this part as a primer bulb.
@@Rein_Ciarfella I think we’re talking about 2 different things here. The older Briggs and Stratton engines and some of the Tecumseh 4 cycle engines had a primer. I don’t know of any modern 2 cycles that use a primer bulb. If the machine has a separate choke lever with a bulb it is a purge bulb. If it doesn’t haves a choke system with just a bulb it is a primer.. All a purge bulb does is circulate fuel by pulling it from the tank,through the carb, and back into the tank. You can push it a hundred times and it will not flood the engine. All your doing is circulating fuel. If you have a choke lever with a bulb and it’s squirting fuel your carb is junk.
@@andybecker2693 what about the fuel line / primer line they mention? On cheap china rotary carbs the bulb is sometimes separate and you connect one end on the fuel filter and the other to the carb near the H valve (fuel inlet valve?) and the third line comes down in the tank. On this example the fuel filter line is connected under the bulb and the bulb outlet seems to be the fuel return line to the tank. If the two lines are just circulating, one must have a one way only (bulb has a directional valve?) and the other one is used by the vacuum produced by the engine and be the one for the fuel intake. I saw many times fuel filters connected directly to the bulb and here it's the other way around, this and the fact that it seems the bulb is just a recirculation and not a primer got me confused as to where and when connect the fuel/"primer" lines. Maybe you can shed some light on the subject. Thanks.
Hi there I thought you did a fantastic job rebuilding a carburetor good job. Although after seeing the saw cut through the wood log I could tell right away double chain was was not very sharp he should have cut through that like butter anyway cool video thanks Dennis
take a dremel with a small cutting wheel and with a steady hand cut some slots for a pocket screwdriver... depending on the location of adjustments you can cut into the carb body with no ill effects...
You can easily remove both H and L adjustment screws to cut slots away from the engine. Wrap the threads in painters tape, place in a vice and cut slots much more precisely. :) That said, a splined tool is much easier to use for adjustment as once you've got it on the machine it is aligned with the screw and won't come off or go out of alignment until you remove it.
Most troublefree devices that I've ever come across. Keep your air filter element clean and you're ok. If theres need, you can easily adjust for ideal engine speeds.
You are the right person to ask about carburetors. What are the differences between 2 cycle and 4 cycle carburetors? Only differences I see is the spring in 4 cycle carburetor fuel pump side which 2 cycle carburetor doesn't have. Why is there a spring? Now a day, there are no adjustments valves, all factory set. It see to me that the spring in fuel pump side diaphragms causes, flooding in carburetors and wet sparkplugs, difficulty in starting. I have a 26.5cc 4 cycle weedwacker(brand new). I can't get it to start no matter what I tried. I have other 4 cycle lawn equipments with fuel pump diaphragms and spring. They all have bigger engines about 200cc. I don't have any problem with them. Please, let me know! Thanx.
I have a wt141 carb that I would like to replace!I have rebuilt it 3 times and it just will not work properly!is there a cab that will work on this that has same ports in the same places,I can’t make house case changes!
I have an old craftsman chainsaw with a Walbro WT 20 carb. Is there a video that shows how to tune that carburetor. I'm having trouble getting the saw to idle? Thanks
"Draw the nozzle check valve up against the retainer 2 or 3 times to insure it's working properly." I know what you mean but, most haven't got a clue what all that meant.
Hey Grey, I think many Stihl small 2 cycle engines use Zama carbs check out the Zama carburetor channel. They've got a vid of a complete rebuild. Cheers.
Hi i have a brushcuter with a fully plastic carb and nobody has herd of that not from usa canada or uk its by walbro from the 90,s how can i buy a new one please
I have a 2cycle generator from Harbor freight with 800 to 900W. Would you have information on setting the timing of the generator I have had a problem on mine, which I believe is the timing. It jerks the starter cable out of my hand when starting. It may be trying to fire be it is supposed to. Thanks! Regards, Robert Fern
hello walbro friends I have a walbro wj 71 carburetor I would like some help I am having trouble knowing exactly the height of the needle lever, I cannot find the service manual for this carburetor thanks for the help
Thank You for the great video and information. I have the problem of a leaf blower from the 90s, The carburetor has large numbers 041, Smaller numbers that looks like w 1538. I cannot find a rebuild kit number for this part number. Can You help me with this problem? Yes, It is a WALBRO. Also it looks like I can't remove the screen without destroying it. Again Thank You.
OK it's a WT 538 not a W1 538 Walbro carbs on weed eaters and chainsaws have a WT plus 3 numbers following ....... The screen is easily taken out with a small pick... Like a dental type pick bought at a drug store.......
I like it how they call the high and low idle screws "tamper resistant" like the owner is "tampering" with something they aren't supposed to. If I buy something, it's mine and I can "tamper" with it all I want. It's my property.
I don't have the walbro pressure tester. I do have a mityvac 8500 vacuum/pressure tool. I have pressure tested many walbro carbs and I can NEVER get the results you do. Most of the time the pop off pressure is almost 30 with the reseat pressure is around 15, even when I rebuild and adjust the carburetor. When I reinstall the carb the unit works just fine. Why? am I doing something wrong? Should I do this test dry or with fuel in the carb?
I have a Walbro WT 471 (non adjustable high speed jet) This Homelite Yard Broom (blower) does not have a throttle trigger but only levers on the choke and throttle butterfly-for two speeds. Question...the high speed jet has a fixed plug in it, sticks out about 1/2" and I cannot turn or seem to do anything with it...what are my options? The engine seems to load up with gas, I did install a new primer bulb, needle, and metering diaphragm. It initially ran excellent but then started to load up with fuel, lose power and bog...spark plug is soaked with gas.
i got a brand new Al-ko 154 with Walbro WT688 and it wont start right out of box. Plug keeps getting wet. Has spark and compression.WTH??? Fuel is good and keeping decompression pushed in while starting. What is going on?
When start my chain saw up. Races up will not go to IDL even if making adjustments on side of carb. Would crankshaft seals have anything to do with it? Thank you and great job.
I just rebuilt a WT318 that has a plastic plate under the primer bulb that is the return to the tankand now It will not prime. I used kit # K10-WAT, I tried the stiff blue and the flimsy black rubber pump diaphragms, made sure the one way valve under the primer bulb was closing and opening, set the metering needle flush with the body replaced the screen, poked and blew out all of the holes so what am I missing? Is there supposed to be a rubber grommet in the needle seat?
Tamper proof is tantamount to non-repairable. Unblocking wee jets on carbs by air blasting necessitates removal of the screws. As with all equipment, tamper-proof means early consignment to land fill and increased material consumption. Would be nice if legislators had the wisdom and tech savy to think things through. One also finds with 'new' fuels or to compensate for wear, carbs need a tweak to get machines to run cleanly.
@@joecasual2952 We can thank our politicians for opening up our economy to the Chinese, combined with Americans choosing lower price over quality. Made in America with global parts does not give me any comfort. Would you want an American surgeon replacing your hip/ pacemaker/etc from one made in China?
Never a truer set of words. These people seem to infesting all aspects of life, but we are not suposed to mind. the thousands of basicly good machines scraped off to prevent them burning a litre of petrol a year, and "destroying the planet". Well the people doing that are destroying me..... Same with a few other things as well. None of these things do as good a job as they did ten or twenty years ago. But say nothing......
Weed wacker trimmers saws need a carb adjustment usually after break in or lots of work hours on equipment do to wear these no tamper adjustment screws suck big time
A FS 66 STHIL WEED WACKER, PURCHASED BACK IN THE MID 1980S I THINK, WHAT IS THE PROPER PROPER CARBURETOR. ACCORDING TO MY LOCAL JOHN DEERE DEALER IN HENDERSONVILLE TN, COST APPROXIMATELY $95.00. I’ve researched google and for some reason I keep getting conflicting information. I know it doesn’t have a primer but that’s about all I can give as additional information. Thanks for responding in advance
Great video!thank you! Hope you can help me. If i pump my primer bulb air goes out but no fuel comes inside . I already changed all gaskets and diaphrams and screen with walbro rebuild kit and used air compressor in every hole. Should i try to remove the welch plug?? Thank you
You may have damaged the check valve in the carburetor if you used too much compressed air. Provide carburetor model number and I'll see what else could be occurring.
It's a walbro 668. I know that valve can not be fixed.Can I do anything to it other than compressed air? Carb is 9 years old. Is it better not to leave fuel inside the carb after use to prevent this? Many thanks
the valve is the problem..today I noticed that if I close the hole of the check valve fuel comes inside. It seems impossibile to remove without drilling it..how can i do?thanks
mi maquina es OLEO-MAC y cuando la acelero,hace como si quisiera apagarse,y solo en algunos momentos acelera bien,sera esto problema de carburacion,?? y gracias por su tutorial
How about a DETAILED TESTING and troubleshooting video? That would benefit your OEM customers by reducing complaints. Covering the similar but somewhat different HDA series would be nice too. It's not as if production costs for this style RU-vid video are high and it would also improve the customer experience.
