How To Test A Vacuum Operated Fuel Valve 

Dude- people like you are making the internet great again! Thanks for sharing your knowledge out to us plebes.

WOW my friend, you explained SEVERAL issues happening now on my 2000 dyna twin cam 88. Knowledge is power and you are a powerful person! Thank you for sharing it, with us all, and helping save us all time, headache. And money. People like you my friend this world needs more of. God bless you...

Dude you saved me I doubt you’ll see this since the video is so old but my bike was running ok had some backfiring so I changed plugs started her up again then went back changed oil coolant gear oil air filter sub air filter fuel filter put it all back together haven’t been able to get it to start didn’t even know my petcock pulled a vacuum the manual says something has to be clogged so I’ve been blowing everything out thought maybe the fuel line was air locked pumped fuel into the line by hand was about to give up and take it in and just found this video you sir are a god damn hero

Cody you are the man I've had Honda's my whole life and I'm old! I understand the vacuum system on these fuel valves and the one on my 1500 is working good so far but now I understand after you gave that wonderful explanation of what's all involved with that and what to expect! Thank you so much for the videos you are extremely helpful!

After I split and cleaned my carburator s on my GL 500 Honda. Rebuilt the carbs, and took me 6 months of fustration rebuilding so many times. I finally saw your video. Taken it off and cleaned it throughly. Assembled it and fitted to the bike. Guess what. Urrika moment. Thank you so much. Even after 5 years of you making this vid, people profit from you valuable knowledge. Thank you very much.

This dude made the perfect video where he showed the inside of the vacuum diaphragm, i mean how it works!!!

I'm currently trying to get an 02 kz1000 running that sat for like 2 1/2 years, pulled carbs out, completely nastiness, floats stuck, the works! your videos have helped a lot for sure, thank you.

I finally have a use for my Vacuum pump that I purchased in order to bleed the brakes on my 4x4 Silverado, and my Yoda Avalon. I did learn how the fuel petcock works, I did not know before watching your video. You did a perfect explanation of how the unit works, and better yet you provided examples of hard to find vacuum leaks and other defective component within the Fuel petcock itself. I now have the confidence to rip into my Katana 600F, this bike has had quirky fuel issues since the day I bought it online used. The bike did not even run when I bought it, me and my friend Mike bomb started the thing for 1/2hr just so I could ride it home, because I did not have a ramp at that moment. I found your explanation very concise on how the unit "should work." And I really enjoyed the part about hard to find leaks in the system, and what to keep a lookout for in defective parts. Thank you for sharing your knowledge. The Katana has had 3 carb tear-downs and a ultrasonic carb cleaning, and untold # of cans of Seafoam. I unloaded the parts Canon at the bike with brand new aftermarket Coils that come with the plug wires, 2nd set of NGK plugs, a salvaged CDI Ignition box. It ran fine for a couple of years, took it to the car wash and this bike has now turned into the money pit. Honestly, I really had no idea how problematic these petcocks were, now since I understand how they work after watching this RU-vid video, I hope to solve the mystery that has stumped bike shops for 5 years now.

Hey bro.. let me just say.. not only are you a beast when it comes to this but no one else explains and shows things to the level of detail that you do and straight to the points.. I appreciate you. I had a scooter for work sit for 3 months and went crazy trying to clean the carb... ended up that my fuel pump/peacock valve wasnt working correctly.. i would get gas sometimes and sometimes i wouldnt get any.. i would get enough to fill the lil plastic filter before the carb but not enough to rum the scooter... took me 3 days to find out i wasnt getting enough gas cuz it looked like i was and the bike ran sometimes for a day and then not turn on... lol $6 fixes my issue... any store wouldve charged me the 40 for carb cleaning and goddknows whta else

Dude , I appreciate thus video so much, I just rebuild an 500vt and got it back together and the petcock leaking bad. Tried to clean and repair it but everything looks good. Now I know I just need to replace it.

Great video! I have a go kart that is leaking fuel out of the exhaust, and you have further reaffirmed me that it is this device along with the carb floats. I noticed when trying to start it up, fuel leaks through the vacuum hose. I also noticed that when the go kart isn’t even running, it is leaking fuel out of the exhaust, indicating the carb floats are also a culprit. Thank you so much for this! Very informative!

Man! I wish you were my next door neighbor. I love how you teach this stuff. I’ve done several kinds of fixes successfully from your vids. Well, I guess you are my next door neighbor in that way. Thanks for the great content.

So helpful Cody - I did not know this vacuum valve could cause so many issues. Great video Sir.

Thank you,, thank you, thank you for taking the time to help. It was just what I needed, I had everything, gas in the floor, did not start, and finally the petcock with a tear that I found thanks to you. .

Hey dude thanks for the info, I have a 1994 CB500 with the same issues. Thanks to you I know what to do. Awesome.

Awesome man..Mine just started running out of gas when the tank got down to about 1/3 filled. I took it apart and stretched the spring and it seems to be working. More testing needed though. It's a 2002 Honda Nighthawk 750.

A couple of years late to the party but this video just answered my question about the extra hose ports on my petcock and my carbs. Thank you.

thank you man iv'e been fighting with card setup issues for 4 days just to find out my fuel tap is ''broken'' and i'm seeing the same symptoms you have described runs fuel out for a bit then stops, i'm going to replace it tomorrow for one that works. thanks again for the help

I see this video is 5 years old, and after taking apart Mt bike and carbs 8 times I was close to scrapping the bike, until I had a funny feeling it was the fuel tap and after watching this I am pretty certain it is, I've ordered the parts so time will tell, Thanks alot for the video

Best motorcycle mechanic on the internet!

Great information, very helpful. It helped me to get my bike running perfectly. I did not imagine that that was the problem.

Great job explaining how everything works, what properly working vs failure looks like, and how to test each case. My vacuum port was somehow completely clogged. Thanks!

I googled fuel issues for my older harley sportster and this video came up. Very informative, thank you.

Great video, Cody! Well explained, extremely informative. Thank you for taking the time to educate.

This was great and EXACTLY what I've been dealing with on my 2005 Shadow! Thank you for the information!!!

Thanks very much for the tip. I paid €78 for the part with the broken membrane. The valve was located on the right side of my super Magna, half way cylinder 3. It was easier to suck it without the tube, since the other end was difficult to reach. Thanks again.

Great relevance for this. I attempt to ride nearly everyday and all year long but am always vigilant about this little bugger. I replacement for my 97 1500 Valk is about 50 bucks, an easy amount to spend in light of the havoc it can create if it fails. Well done video, right pace, good framing, spot on.

Thank you man, this is the prob, i had on my cbr900rr sc33, now its done thanks to you

Great video. Have have no end of trouble sorting out a fuel drowning problem until I came across your footage. Thank you.

I suspect this may be my problem on a Suzuki, I wanted to see how the inside of them worked, not a lot out there, the factory diagrams are not great. From the moment I got this bike I was confused why it had on, pri and res but not a off position. Started leaking gas the first time I filled the gas tank. I noticed the second tube when taking the carb out to send it off to be rebuilt and saw gas flowing from both tubes. Thought nothing of it until I saw the factory manual did say it was a vacuum hose only so that was my first clue. Great video. Still helping people 4 years later.

KAWASAKI VN 8OO this vid has totaly explained the vacum petcock that is causing fuel to flow from the over flow pipes when not running. Great vid

Thanks for sharing your knowledge. I’ve had this issue before and never really understood how the whole vac. Thing worked. Thanks again !

Thank you for helping me find the problem!! The diaphragm failed just where you showed in the video! I would never have found the leak if you had not showed where to look!

just got my first bike yesterday. 1985 Yamaha Virago/Maxim 750. needs tlc but it was a good price for $500. the guy said it had a clogged petcock. I had already looked up the petcock stuff and knew it was vacuum operated. your knowledge on this however, earned a sub from me xD

Thanks brother. U helped me figure out my issue on my 2003 Suzuki Volusia. Keep the helpful hints and keep education coming.

Lucky i found it...i basically placed the spring down the bottom cause when i opened the petcock...spring jumped out... didn't know where suppose to be... your explanation show exactly location of spring 🙏

Really nice on how you had explained how it works and how to test a Woking vacuum operated valve. Thanks and keep up the great work.

I'm having this problem with my 96 F3. The vacuum has been changed to a standard flow. So right at the end if your video you said it! Gas getting into my valves n into crank case. So I've done everything else... ECT. My wife said clean the damn carbs. The bike was sitting for over a year. I was trying not to go through all this cause I just wanna scream the BIKE! So looking like carbs are coming off! Thanks so MUCH! I've been working on n racing over half my life. I'm 36 so... I'LL let you know brother! Thanks again

Just had the peacock flow problem on my sun atv and solved after watching your great video diy/how to!

Thanks Cody! I appreciate the info on that.. I'm going to order a new one.

Great video! Struggling to get my 2001 Valkyrie to run. Starts and runs easily and fine when I inject starter fluid. Tested vacuum valve, but did apply vacuum for an extended period. Back to the garage!!! LOL!

Thanks for putting this out there. People need to know about these vacuum valves, and more generally the evil ethanol works on their bikes. I've got an old XS11 that had four carbs rebuilt right before I bought it. Bad cocks (due partly to gasahol) are why I had to rebuild them all again as soon as I got started rehabbing her.

Thank you for answering all my questions you're awesome dude Related to the fuel regulator

Well spoken, easy to understand its clear and simple information

I'll be sure to check mine tomorrow when I balance the carbs!

Thanks, I'm helping my French neighbour by re- conditioning the carbs in his Yamaha FJ 600. I rebuilt them, but when put back together, there was a fuel leak by the fuel prime- on-off lever. I'm an ex road racer, so not completely stupid, but needed some pointers as to the vacuum and "Primer" workings. Pretty sure that tomorrow will get it running ok....... will let you know.

Thank you, You mentioned it backfiring all the time when running and actually I noticed that I forgot to turn off the fuel so when I went to try to start it again. it was flooded SO.......I think I'm not holding vacuum. I'm going to try replacing it. simple and cheap fix. Hopefully that works. Thanks again

Thank you! this is a new learning I did not knew this exist!

Code, thanks brother. Trying to fix a scooter for my son and this is a big piece of the puzzle. Thinking of replacing the whole system with a Honda oem electric fuel pump and a pulse doohicky from probld.

Thank goodness I found this video, I was losing the will to live coz I couldn’t remember which order the diaphragm and insides went back together. Really helpful, you have another new and grateful subscriber, thanks for sharing Cheers from the GB Col 🇬🇧👍🇬🇧👍🇬🇧

I replaced the leaking petcock diaphram spring etc with a kit. Now i have no gas getting to carbs? Blew and sucked in the vacuum line going back to motor , no blockage. I did replaced the strainer with a new one that had a larger o-ring on it? Thinking carb trouble ? Thank you for your help you do a great job for us dummies !!!

awesome dude u make mechanics of all of us.... u hit my problem square on the head with this video shout out 2 u and thanks from south africa cape town.

Very informative, just had a huge leak from a petcock on a bike that had been sitting for years. I cleaned it tonight but am unable to test it yet. I think it had the final scenario you were talking about, just covered in gunk and got stuck open. even if it gets stuck again tomorrow, at least I will understand why as I buy a new diaphragm. Nice job!

Thanks dude, you just really helped me out with trying to work out why my 1500 Valkyrie is overflowing petrol after a carb rebuild. My petcock was completely rotted out. Not a split in the diaphragm, there wasn't even a diaphragm, and the vacuum hose wasn't connected either. There was a shit load of backfiring under de-acceleration and not running on all 6 cylinders. That said, the mixtures on the entire left side were way out too. Your video has been very helpful.

It’s like a carburetor had intercourse with a master cylinder..and we now have carb junior. That’s insane you had that many in a month. My bro...I took mine off I’ve heard far too many bad things..needless to say the recall on them. Good video btw you always come through. I like that you break down the entire thing..some of us are new to this..I appreciate the time and effort. Thanks my man

Great vid. I'm having a few running issues on my 82 Gsx400f and this will now be added to the list of things to check. Cheers.

U the man very helpful my guy thank you for taking ur lil time to make this video

Thank you I got a 50cc scooter TaoTao and I've been fighting this problem for a couple of days trying to figure out what to do actually I think the petcock is okay I think my vacuum hoses hook to the wrong spot I subscribed and I'll continue to listen thank you again Chuck

Thank you that is exactly the kind of problem that i have

Awesome information Cody, Happy 4th of July Dude.... Ride on !

Really informative. Thanks for this. I have been suffering a "niggle" on my 2000 Hornet - after riding for about 20 minutes it wants to cut out at idling speed. If I stop for a while i recovers. An experience mechanic suggested that an electrical problem affected by heat would most likely be the problem, but couldn't fix it. Having just fitted a clear fuel filter in the fuel line, I can see that fuel flow is the problem. I'm going to investigate the fuel tap and diaphragm. Cheers.

Yup, leaking peacock on my 2004 VTR1000! I kept smelling stale gas in the garage. Hadn’t ridden the bike for a while and started to look around the engine and found it dripping gas from the small peacock vent nipple. New peacock $275, repair kit $25. Saw your video which supported my assumption of the problem. I keep my tanks filled with AvGas to keep the ethanol from corroding the carbs. Still think emulsion tubes in carbs could be slightly plugged... time to disassemble carbs and clean emulsion orifice with .009 guitar string!

Thank you very much, this video saved me several headaches, really great job explaining all this.

Great video you helped me solve my problem with my cbr900rr. Slide note I purchased a new/rebuild petcock on ebay and it failed within 20 miles and left me stranded. From now on I will only use genuine Honda parts.

Thanks cody. I have gas coming thru the vacuum hose into the #2 carb and its running rough and the #2 cylinder header pipe is not as hot as the others. Now i know thanks to you i shouldn't have fuel in the vacuum hose. I ordered a rebuild kit for the fuel valve. I hope this solves the problem.

I think this is what’s wrong with my vtx. It’s been backfiring and now it acts like it’s not getting fuel. Thanks so much for the info!

I love you man.. I finally was able to solve my bike problem

Great video, thanks for explaining. I recently noticed fuel smell in the engine oil of my Honda so I guess my valve is shot, too.

Thank you! my 1999 Honda CBR900rr Petcock diaphragm went bad thanks to you I would’ve never checked that, it was driving me nuts I pulled the carburetors cleaned them, change the spark plugs check the coils it was driving me crazy then after watching this video I checked the gas tank petcock valve -WHAMO- damn that was it. 👍👍

Thanks from the bonnie Highlands of Scotland 🇺🇸 🇺🇲

Good stuff! This guy sounds like Edward Norton if you close ur eyes I can hear fight club lol.

Thanks bro, I will check it out on my 750ACE. Excellent video, I believe that you know your stuff. I like how you explain the different scenarios of possible problems. 👍👍

Perfect advice "JUST RIDE YOUR BIKE!!!!!"

bout to be on my magna soon thanks to your info thanks

Thanks for the explanation. I like the ultimate solution. Ride Your Bike!

Kodi great info I sent your video to my son who is having this problem thank's mate

Great description of the fuel cock. I just discovered I’m missing a spring seat between the spring and rubber diaphragm. Thanks for the great info. Btw, my 1984 Nighthawk S was sitting in garage for 15 years (last insured - 2006) and it started up after replacing old fuel and battery. Now I will take your advise, “Ride your bike”.

fuel valve information phenomenal news flash

NIce one, mate, very informative and clear. I have a VF500 and your video has given me the information I need to hopefully diagnose my fuel supply problems. Cheers!

Having problems with my 1992 Nighthawk. This video was very helpful'

A 2000 Suzuki sv650 brought me here. 😂. Great video🎉🎉

Very helpful and well explained, very clear 🤙

Mine isn't shutting off the fuel. So over night fuel has leaked onto the ground. Not much but enough to smell it and the bike starts half flooded. Carbs where rebuilt two years ago. I used your video to help sync the carbs. Thanks for the info.

Good info but I wish you would have covered the testing a bit more thoroughly. I have two of them that won't shut off on a 1980 Yamaha XS850SG. I replaced all of the diaphragms and o-rings but that didn't change a thing. Showing how they are assembled would be very helpful!

I think a fuel valve with just off, on and reserve is better. Less failure points and you can still stop the fuel flow to keep the engine and carbs safe. This is still a great video and helpful for my current kawasaki KE175 with vacuum valve problems.

Replacing my 90's Suzuki DR125 Pet cock because of leaking. Found an extra tube going back to the carb ! !~ So, looks like I have a vacuum fuel valve (WHO WOULD KNOW !). Anyway, will dig into it and see if I can find a problem with the Vacuum fuel shutoff. Would be nice to not have to buy an entire new Pet Cock assembly. Thanks for the nice easy to understand video !

great knowledge sharing. tqvm for this good intention - to spread the knowledge for whoever need it especially guys working at workshop and also to DIYer like me. god bless you and your family

Had the "sticking" problem on a Suzuki GS500 due to contaminated fuel (due to corrosion in the tank) which I had no idea what was going on ; I now know exactly what happened back then ! Thx

Thanks for sharing , i was scratchin my head last night cause i couldnt figure out why i wasnt getting fuel on my kitanna , never even knew they had vacuum powered valve

This aged well. Yeah this is a forever video. Well done Sir

09 vtx1300. Used my brake bleeder vac pump and diaphram would not hold vacuum..! Thanks for varifying it for me...!

Thanks for posting, great info. I was confused early on in your demos of vac. operations as seems Vac has to be constant/strong for good fuel flow versus weak and leaking AIR.

Awesomely done. I will be doing this today. I found you on Goldwing Docs. You definitely belong there. My 1500 has fluctuating idle. and backfires when I romp on the throttle shifting between gears. It did sit for over 1 year. I'm back on the road but,I know it can be better. The gas smell has been haunting me since I get it 3 years ago. Much appreciated advice. Thanks. BEN.... (FLORIDA)

My CB600f Hornet has a big blob of clay or similar inside the fuel valve blocking the vacuum pipe. I guess that the diaphragm tore and somebody decided to do some serious bodge job on it! Bike did run fine for a few hundred miles after I bought it, however then it started running on three, breaking down etc. So I'm fixing it up to run again. The more I take it apart the more bodges I'll find I bet!

i learned something new. my 82 kz, vacuum operated, mikuni carbs. i have yet to pull the carbs off. turned fuel valve on and fuel came out my intake pods and overflow hoses. ill check my oil for gas.

OK OK OK. But my Bandit 1200... You know.... Very clean but been tampered with. (I've got my Nighthawk "West Virginia" container find but that bike is getting lonely). Then my tampered with Bandit. A very weird gasket in the petcock. Got the rebuild kit. Did all of that. Then the flat gasket there inside the petcock same size as that smiley face gasket left over. Then the suction tube pugged with a big screw that's been there a while. I guess (whoever) in the past set this up to bypass the Vacuum system, just dumping gas into the carb. Ever hear of this??? Thanks for sharing all that you do. Your humble servant. ~ Steve from New Hampshire.

great video mate. very informative thanks for sharing.

Learned something I didn't know, Thanks again!

Dude I have been stumped on why my bike is running like shit (it’s a 89 transalp ) I think you just helped me figure it out. The cylinder it pulls vaccum from keeps fouling out and running like shit , I’m going to run it off of a gravity fuel bottle and see

Very good explanation.