Likely a sticking float , clogged jet or airleak . probably time for a carb cleaning.
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18 years ago
Likely a sticking float , clogged jet or airleak . probably time for a carb cleaning.
This often happens when the speed regulator (governer) doesn't work right. These engines have air vanes, and often times a squirrel or some other critter has made a home inside, and the nest blocks the vane.
Take off the top cap (around the spinning part on the top, where the pull cord goes in) and I bet you find it. I used to do this every spring to mine.
Re: Briggs-Stratton Quattro
Seven-yr-old MTD 22" rear-bagger. 4 hp Briggs-Stratton Quattro, well maintained, doesn't smoke, oil level fine, carb is clean in/out, air filter has been cleaned.
Motor starts fine, than it revs up, then nearly dies, then revs up, then nearly dies, etc etc. It -does- carbonize spark plug electrodes ("black plug disease"), and I thought that was the problem, but when I put a fresh plug in, it ran the same as with the black plug.
Anybody got any idea what might be going on?
TIA, Puddin'
****************************************************** *** Puddin' Man PuddingDotMan at GmailDotCom *** ******************************************************;ive seen many of these with the small passage in the fuel bowl nut clogged. you can take the nut off and use a needle or a tag wire to run thru it and then blow it out. this is also a good time to take the fuel bowl off and was it out. if you still have a problem after this. i would snug up the head bolts, check the flywheel key to see if its partially sheared. there is a oring that goes on between the engine and the carb that may be worn,, or the tube that the oring goes on may be worn ,and a gasket on the other end of that tube that may have blew.its easy to check the intake tube while your checking flywheel key. ..... another common problem is the valve clearance closes up so the valves dont shut as well. you can use a file between the lifter and valve stem to get the clearance back where it should be..006 intake,,,.011 ex.at top dead center.. lucas.
All carbs have a fuel bowl and float system or you would have a direct flow of gas into the motor filling the engine completely with gas till it would run out the carb and exuast, even filling the crankcase to all gas. The fuel bowl is not in the tank.
hi, if you have the type carb that has a flat gasket between it and the tank,, that rubber gasket can cause it not to run if it gets streched.. lucas
To repeat, it is a B&S Quattro, 4 hp.
I could find no fuel bowl nut.
Fuel bowl is part of the gas tank. Can't take it off. But I cleaned it out. Wasn't very dirty, minimal residue only.
Head bolts were tight.
It fouls spark plugs. Gotta be a fuel/air mixture problem. Carb/tank is all clean, no apparent problem. Compression feels a little weak.
Still don't know what the problem is ...
Why do I see so many B&S mowers sitting in the alley waiting for the trashman? They are made to be lo-price. To my knowledge, "They Ain't Much Designed To Be Worked On".
Thanks, Puddin'
****************************************************** *** Puddin' Man PuddingDotMan at GmailDotCom *** ******************************************************;
Last week had the same problem with my 10 year old murray with B&S 5hp Quattro. (Lets remember that these engines have a 250 hour life expectancy from B&S) Mine ran/runs great and hated to throw it away just because I left some gas in the carb over the winter. Self propelled costs around $300 to replace.... now it looks like I'll get at least another season out of it..
You'll need to google +"Briggs & Stratton"+Quattro or go here and look for Engine IPL (illustrated parts list) to see the breakdown
Once you find the B&S web site, search for that model number. You'll end up with probably a .pdf file showing breakdown of engine.
Note that there is probably more than one model carb for your engine , you'll have to figure which one. Usually asks, do you have choke or primer bulb.
On mine (which may vary quite a bit from yours) I had a bolt in bottom of carburetor bowl which acts as a jet. Using carb cleaner and very fine wire (I used safety wire) clean the gunk. Clean the gunk from needle and seat under (above) the float. My "carb to intake" seal is a "O" ring.... Looked fine. I had to take carb off, put back on 3 times till I decided to put a little gasket sealer on flange near "O" ring to help seal. On these engines a little vacuum leak will cause it to not suck gas.. Till I found this air leak, mine would run great as long as I kept pressing primer bulb.
I spent $8 to fix mine including oil change and pull rope change.. If it wouldn't have worked after that,, I'd have dumped it.. It being
10 years old.... Chuck
Is this 250 hour life true of the older B & S engines? If so I have several living in the twilight zone. But then I guess that figure must be an average.
Colbyt
I saw the 250 hour figure on the b&s web site,, but now older ones are probably different.. Modern ones ya can't even adjust mixture (but no need to if it's already right.) No idle speed screw.... Chuck
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