QuestionQUESTION: I recently purchased a Briggs and Stratton 8000 Watt "Elite Series" portable generator. It has the 15 HP B & S 392cc Vanguard engine (Model # 246435). The generator has a high speed miss with no load applied. There is no miss with loads applied that total about 1000+ watts. When first started, it takes about 1 1/2 to 2 minutes for the engine to begin missing. The miss is intermittent (occurs about 10-15 times a minute). It does not affect the voltage output of the unit, but it sounds unusual to me. I can manually make the miss go away by closing the choke lever ever so slightly (but it's not designed to run in this position - between fully open and half choke). I talked with a B & S technician who operates a small engine repair facility in my neighborhood. He claims that these newer engine designs of the day have non-adjustable carburetors that are set so lean due to emission regulations that a miss such as this is not unusual. He says there is nothing that can be done to eliminate the miss, and that I should not be concerned with it. However, it still bugs me, and I do not want to harm sensitive electronics in my home when using the generator for backup power during outages. What is your opinion/advice? Thank you.
ANSWER: He's right. Now there's no harm in giving the carb a good cleaning, you may have a condition where there's a slight blockage and limiting the amount of fuel pulled into the venturi. That coupled with the emissions carb would make the problem worse. You might try using something like SeaFoam in your fuel. This should help prevent most varnishing or gumming up of the carb.
If it does this under a load, then it's definitely time for a complete service. But if it's only when no load is applied, and at high speed, then it's probably normal, or near normal.
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QUESTION: This unit only has about 3 hours of use since purchased new. Would you still recommend a carb cleaning, just in case something is "hung up" in there? Thanks.
AnswerIf this is still under warranty, I wouldn't do anything to it. I'd contact a Briggs Authorized Repair Center. If the shop you took it to is authorized to do warranty repair and he said it's not a warranty claim, then a cleaning won't hurt anything. If it set up with fuel in it for longer than a month, then I wouldn't be surprised to see some varnishing in the carb.
Personally, if it runs good otherwise I'd just use Techron or SeaFoam in the gas. Unfortunately we're stuck with these emissions carbs until fuel injection systems on small engines become more widespread. Some rough running at operating speed with no load seems to be one of the things we're stuck with while technology catches up to the new rules.
If you notice any other operating problems, like running rough under a load, then I'd definitely go into the carb. Thanks, PK.
