carb adjustment

[mongolio]

Got a 1977 Simplicity Sovereign 7016 with 920 hours. Thru snow GREAT all winter, but broke it out this spring (after cleaning out a collosial mouse nest & taping up some bare wires) & she seems to be missing a bit. Seems to run better half-choked, but that only lasts for a while, then the symptoms seem to get worse.... sputtering, loss of power, a little back-fire thru the exhaust, etc... I can see small puffs of black exhaust @ low idle. Not a large amount at all. I think it's safe to assume a carb adjustment is in order & am half convinced to tow it the 3 miles to a Simplicity dealer & have them fix it. The cheapo in me say I can figure it out. Do I reset the carb from scratch? What tells me a too rich mixture vs a too lean mixture? Thanks in advance

[Mel_W]

use your ears. listen for the most even, smooth, rpm. Mel

[PatterBrian]

I had the same problem, plus surging on a 4041 I just bought. I poured some Seafoam in the tank and it got a lot batter after running about 20 minutes.

[mongolio]

I did pour some in as well, yesterday afternoon. Maybe it just needs some time @ idle so it can run thru, then hopefully a "tweak" or two, & she'll purr like she should. I just hate tweakin' on carbs. They are not my thing.

[TommyK]

If the tractor's been sitting a while, most likely as evidenced by the family of mice setting up house keeping, and the tank had gas in it, the gas could be bad. Time was gasoline refiners put a lot of stabilizer in gas as they made it as fast as they could, as much as they could, then stored it. A funny thing happened a couple decades ago, the refiners realized keeping fuel in inventory was expensive. So they slowed production, dismantled their storage facilities and more closely matched production with demand. I would be surprised if the fuel you put in your car today was refined more than a couple weeks ago. This did two things, it caused any hick-up in the supply chain to cause havoc from short supply (ask anyone from Atlanta, Ga, what that is all about) adding wild volatility to the market price. The other thing is it caused the refiners and distributors of gasoline to use less fuel stabilizer. This yielded gasoline with a short shelf life. Alcohol in the gas too can cause storage long term problems. Drain that cheap $3 fuel from your tank and replace it with fresh $4.25 gas. Dispose of the old fuel properly. Then thread the fuel mixture needle, on the carb, all the way in until it stops. Don't put too much hurt on it or you'll damage the needle and seat. Back the needle screw out 1 and 1/2 turns. Fire up the engine. Back the fuel mixture screw out (counter clock wise) until it sputters from too rich a mixture, take note of it's position. Then screw it in (clock wise) until it sputters from too lean a mixture, taking note of the position. Then set the screw about half way in between. After the engine warms up, about 10 minutes, repeat the adjustment procedure. You should be good to go. I had a hard to start, foul running problem with my pusher a couple years ago. It and my 2.5 gallon gas can sat idle for about a month and a half during a particularly hot dry period when the grass quit growing. Sure enough, I got a fresh can of gas, dumped out the mower tank and she started right up and ran well. I could see the gas separated in the bottom of the mower tank and the gas can. I don't buy cheap gas, BP. But even the expensiver stuff goes bad quickly, especially during extreme temperatures. Other things that could be affecting a smooth running engine is seasonal fuel. The fuel you buy in January is different than that you buy in May. An adjustment is usually necessary. Today's cars have an engine management system that accomodate this seasonal difference in fuel. The other thing that could be affecting it is ambient air temperature. This may be a seasonal house keeping you need to do with this tractor to accommodate for the vast difference in air temps between winter snow blowing and summer lawn mowing. Again, automobiles have engine management systems that accommodate temperature fluctuations. Garden tractors don't.... yet. If you ask you dad or grand dad, they will probably tell you they needed to adjust or have adjusted their carbs for winter and summer weather. I had several with a needle with a stop on it. 1/4 turn out for winter driving and one quarter back in for summer. But that was back in the old days.

[HubbardRA]

Fire up the engine and bring the throttle up to about half throttle. If you have to run on choke do so. Then back the main jet(the one coming out the bottom of the carb at an angle) out slowly while removing choke till it runs without any choke. Next keep turning the jet till it starts to run rough, then turn it the other way till it runs rough, now set it halfway between the two rough spots. It should run good at that setting.