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Hello, I have a 8 h.p. briggs&stratton L type engine that runs well during idle, but hesitates and looses power when under load. Do you think the carburetor needs to be adjusted or rebuilt, or is not the carb at all? Thank you for your help, Joe

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torinwalker
You should adjust the jets according to the Briggs manual, and if that doesn't solve the problem, delve deeper. You should also read the thread, "Problems tuning your engine?", wherein you'll find a discussion of this very nature, and probably many helpful hints to help you with your motor. Torin...

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Spencyg
I find that when under-load problems arise, the culprit can usually be traced to the ignition system. Check your points, condenser and plug to make sure they are OK. You might also be having magneto troubles. Spence

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torinwalker
I don't find that to be true at all. The ignition, once running, is far less likely to be a problem than the carburetor or governor. The ignition system is simple: A flywheel spins, passing a magnet through a field coil which emits a spark. The carburetor and governor systems are far more susceptible to load factors and should be the first place to look while problems occur under load. I recommend you talk to the Briggs and Stratton Technical Support line. They will help you even if you have an engine from 1965, and they will answer any questions not directly answered by the FAQs. Torin...

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Salthart
Back out the jet on the bottom of the carb bowl about a half turn. This should richen the mix and take out the dead space when you first try and rev the engine.. It that don't help, What I would do next is this..Clamp off the fuel ( some models had a petcock for this ) and run the engine till it runs dry...Now drain the tank and add 1 cup fuel and one cup of cheap fuel injector cleaner to the tank and allow it to flow into the bowl..DO NOT RUN THE ENGINE ! Let this set for an hour or more then loosen the bowl nut without turning the jet screw.. Just back it out far enough for it to drain what is in the bowl while new runs in cleaning the needle and seat ( you may have to bump the bowl loose to drain it ).Once all is drained tighten the bowl nut and add fresh fuel to the tank and start the engine.. Now increase speed slowly.. If you come to an rpm range where there is a miss, let it run there for a couple of minutes as this is likely where the carb trasitions from low to high speed circut and though you will have softened any blockage (Most times anyway) it still needs to be pulled through.. If this don't help I would get a carb kit and do a full tear down and soak. Most any garage will soak it for you for little or no charge.. The above deal is great just before spring restarts and you would be suprised just how good a job it can do.. The STP fuel injector cleaner costs about a buck here and I haven't known it to swell a needle tip or soft seat... I do think you have a lean burn situation from what your saying.. I agree with most of what Torin says but for 2 points.. Yes, a RICH burn will most times hide itself under a load but not a lean.. And while most of the poor run under load situations are caused by ignition, seldom do you see this when there is a smooth idle. It can happen with the old points type engines if there has been an overheat situation and the oil around the point plunger gets thick and sticky.. It will not allow the points to close fast enough and you will get much popping and spitting as the delay causes ignition timing to be retarded. ( oil can get sticky in an engine that has set for a good while also )Easy enough to fix by removing the plunger and cleaning the orafice with carb cleaner and a pipe cleaner.... But this will run the same under a load or not. My moneys on the carb.. Good luck Salt

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don2002
Joe, It might be a good idea to replace points, plug, flywheel key and rebuild the carb with a carb rebuild kit. Depending on the total hours since the last maintenace performed. Also, do you have the original muffler? On older B&S an incorrect muffler could cause problems. Good luck.

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