Briggs and Stratton Quantum- fuel system problems

A video talking about issues with Briggs and Stratton fuel systems. Please post any questions or comments. Making a video of your problem would help me to help you.
Air filter/primer gasket is :795629
Also new carburetors are available for cheap money, not sure which HP they fit but heres a part number. 498170, you can always buy a new carb and swap the bowl nut/jet with the old carb to get the right fuel mixture for your engine size.


Due to factors beyond the control of Alex S “Multikhaz”, it cannot guarantee against unauthorized modifications of this information, or improper use of this information. Alex S “Multikhaz” assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. Alex S “Multikhaz” recommends safe practices when working with power tools, automotive lifts, 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 Alex S “Multikhaz” 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 Alex S “Multikhaz”.



28 thoughts on “Briggs and Stratton Quantum- fuel system problems

  1. If you cant see gas coming out of the brass venturi tube after you prime, then either the bowl nut hole is plugged or you are not getting any gas in the carb. Gotta tear down, clean bowl nut holes with small wire and check to see that the needle and float are moving freely and opening the gas flow. Governor spring can be found via a google search of the engine model number.

  2. Is the long plastic piece next to the caribrator the intake manifold it connects to the engine well mine blew apart a video on how to fix it would b great

  3. I have rebuilt several Quamtun carbs so this is not my first rodeo.

    The engine starts but within about 30-60 seconds it starts to miss and within another minute the engine stalls and will not restart. The plug is wet. If you leave it out and let the cylinder dry, you can repeat the start and stall.

    All carb passages are clean, new air cleaner adapter gasket, flywheel key is good.

    Is it worth replacing the float, needle and seat ?

    Any other things to check ?

  4. I found this post when at my wits end after cleaning (i thought) the entire carb and fuel tank. Your suggestion prompted me to clean all the vent and feed holes with a tiny wire (stripped bread tie) and then blast them all with ether until i saw good flow. Mower now starts on first pull and runs like a champ! Thank you very much for saving my sanity and what little hair i have left. =)

  5. Hi From Argentina! just repaired my Quantum 50. something I did not see int this video is that the jetscrew at the bottom of the carburtator, I had to adjust it precisely to meet the little hole with a mark in the carburator, otherwise the jet will not work or be blocked if you adjust it all the way. I checked this without the bowl, just the jetscrew, and marked the screw up to where I had to adjust. I don't know if it was luck or what, but only this time it worked after 4 times cleaning. GLuck

  6. Hi from Minnesota. I have what looks like the same engine. It won't start when it's below 55 degrees unless I manually go in and hold the choke shut which is a pain. Then it starts like a charm and runs good. When it sits cold the choke is wide open. What's supposed to close the choke for starting?

  7. You're a life saver. I cleaned my carb several times and still could not get the engine to run. I was about to give up when I saw your video and you showed that cleaning the brass nut that holds the bowl is necessary. That was the magic bullet. Motor runs fine now.. thanx.

  8. I have cleaned every hole and journal on my quantum carb, replaced the gasket also, and it still won't prime. There is an additional hole next to the main jet,but i can't seem to find a hole in the bottom of the hole to clean. I hope that you can help.

  9. I have a B/S Intek plus 20 ohv  31P997 engine. I keep getting a large amount fuel entering the oil supply. I can change the oil and filter and its takes about a quart. After a couple of months the oil level will have risen to twice that without ever adding oil. The oil that is drained is very thin and ignites easily. Do you know what is going on? There is no direct link between the fuel and the oil. Any help would be appreciated.

  10. My Quantum has a good spark but just wont start, occasionally gives alittle pop through the carb, when pulling the starter theres like a blast of gas vapour coming back out the carb when the air filter is removed, flywheel key is ok, cleaned the bowl and float but havent removed the carb for complete removal yet, bowl was full of varnished old gas do you think the problem will be up in the carb itself

  11. I have a Briggs Quantum 6.75, about a year old. The carb mounting bracket rattled loose, one bolt lost. I damaged the gasket between the air filter assembly and carb. I have been researching to find out if the engine side of the intake requires a gasket, doesn't appear like it does… can the intake tube just seat firmly by means of the bracket?

  12. I have a quantum 6 that I cleaned the carb so many friggin times and it starts only when its decently warm out. It has that stupid auto choke and a primer bulb that appears to be the same carb that is on yours am I missing that casket?

  13. the fuel line has come detached. how do I reattach? I have tried using a small metal clamp but there is not enough overlap of the fuel line.Suggestions are most appreciated.

  14. This lawn mover eats Quantum Physicists and the String Theory while its running roaring down the lawn. All tho its design is for lawn moving, Stephen Hawking is its primary target.  

  15. YES!!! I have been working on my lawn mower for 3 days and was about to give up when I came across your video. The 1/2" brass bolt was clogged in the jet. I soaked it 3 times in cleaner. Your suggestion to push a wire through it was enough to clear the blockage. It started on the first pull. BTW, the clog was due to a dirty air filter and not clearing old gas over winter. I learned my lesson!

  16. Excellent no nonsense video, no baby crying or dogs barking in the background, and no silly personality issues………………. thanks

  17. Thanks Alex, nicely explained. I'm currently wrestling with a Quantum mower similar to the one in the video, I got it running but it cuts out as soon as any load comes on, or within a few seconds of no load. To me it sounds like it suddenly starves of fuel, but I've cleaned out the carb as described, and checked the (half full) tank is venting OK. Can you think of any reason it would suddenly cut out while revving happily?

  18. Hello. My Quantum 5hp tries to start, putts sort of slow for a bit, then dies. Never speeds up. Sort of acts like the throttle is set to low speed. Plug has been changed. I see spark OK. Carb bowl has gas in it. Only problem I see with carb is the butterfly flap shaft has worn the hole in the carb housing a bit. This is the flap that is connected to the Governor. Any suggestions? Thanks.

  19. I thought I would do a little research before tackling the carb on a mower I bought for $20. The seller said that it will start when primed, but it will not keep running.

    I used to work on chainsaw carbs quite frequently back in the day, so I think I can figure this problem out based on the similarities of principle.

    Thanks for the video.

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