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720 carb

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I have a problem with the carb settng on my 720. I just rebuilt the fuel pump and carb because of some problems and had the engine running Sat after rebuilding the pump and carb. It didn't run perfect but did run. I set the idle needle valve out 1 1/2 tuns as the manual states and the main needle valve likewise just as the manual states. When I tried to start it tonight it would run but was too rich and would flood out and stop. Any help would be greatly appreciated.

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tej
The default settings are only to get the engine started. You need to readjust to get the engine to run properly. When I rebuilt the carb on my B112 it started on the default setting but ran to rich. With a little more adjustment it was fine.

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BradW
Hi Dan. Let me tell you what happened in my case. I overhauled my 16hp B&S motor and carb this past spring. When everything was assembled and all the initial settings were followed by the book, just as you did, it didn't run as well as I expected. What a blow that was. After "chasing" the carb settings back and forth from lean to rich , I finally found a happy spot where it would idle smooth, accelerate quick and run at fast speed "ok". After a short period of time, it would act up and I would find myself adjusting the carb again and again. This prompted me to tear apart the carb once more. The float and tang checked out fine. All venturis were unabstructed. The needles were new. Come to find out..the nozzle had worked itself loose and had backed down and was resting on the high speed needle. When I installed the nozzle, I didn't want to tighten it too much because of it's potential to "freeze up" (nozzle is brass...carb is aluminum...they will fuse over time and become a hassle to get out) So, I re-tightened the nozzle, a little more force this time. Runs great now, no worries. My two-cents worth.

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Sandy_Lake_Imp
The fuel pump kits from Onan come with 2 springs. One is for gas & one is for diesel if I remember correctly. Using the wrong one can cause flooding. The longer one is for gas applications I believe. Bill

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