How to tune an old Onan Genset carburetor

Question

Hi all!I bought an old MH that probably sat for sometime. The generator was surging a bit, so I rebuilt the carb. Now it runs fine, starts no problems. I get 112-116V with on load and with AC on. However, I noticed that the pilot screw has almost no influence. I pulled down the 30Amp main circuit breaker, so there is no load, right? I can close completely the pilot screw and it keeps running, and there is very little change if I open it several turns.  I guess I am doing something less than perfect. What's the correct tune up procedure? Is the strange pilot screw behavior is an indication to something? :?It's an Onan Genset 4000 Emerald I. 1992 model.Thanks,-Guy

dougrainer · Answer

That is not a pilot screw. It is the IDLE adjustment. That screw should NOT be touching anything. The GOVERNOR system is the adjustment. The Idle screw is to be set by screwing it in until it touched the metal and then back off. You then adjust it to when you manually pull the throttle DOWN (lower the RPM) the Idle screw will stop when the output is about 90 to 95 volts. Now, if you are talking about the MIXTURE adjustment on the Carb Bowl bottom, that should affect the running from NO run to surging. Doug

kpackpackkelley · Answer

Give me the model number and spec and I'll post a service manual for you.

grodnay · Answer

Model is 4BGEFA26101H Onan 4000 GenSet Emerald Plus. I got the idle and mixture right, but there's another screw that should set the mixture on idle. Maybe I should force the throttle to idle and see if it has an effect?
Thanks,
-Guy

kpackpackkelley · Answer

This should help you. Bge service manual

grodnay · Answer

Thanks!

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How to tune an old Onan Genset carburetor

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