Carb on Onan 4000 - to be replaced

[Gary RV_Wizard]

Ethanol is indeed a touchy subject - it seems that most everybody has a theory about how terrible it is, based on some fact that may or may not be relevant to engine operation.

What IS a well-established fact is that gasoline (whether ethanol or not) that sits in a carburetor for weeks or months will slowly evaporate and leave a residue that clogs the tiny passages in a carb. Sometimes a shot of carb cleaner is sufficient to clean it out, but more often it requires removal and dissassembly and a thorough soaking/cleaning. That is time consuming and expensive at todays shop labor rates, and still may not be successful if something was damaged or the solvent did not do its magic the first time. For that reason, most techs would rather replace the carb and know it will work, avoiding a dissatisfied customer and a "do over" repair they probably cannot charge for. For that reason, carb cleaning and rebuild is a disappearing service, done mostly in back yards and country shops.  I've become rather expert in removing and cleaning the twin carbs on the outboard engine of my bass boat, which doesn't get used very much.

 

[zmotorsports]

I agree with Gary that many shops will not even touch a carburetor any more, whether on a car or generator.  If they mess with them at all they R&R (remove & replace) only.

You could pull the carb off and clean with solvent to see if the circuits can be cleaned.  Usually the idle circuit is the first to suffer symptoms due to its size being much smaller than the main metering circuit.  Fuel residue is usually the culprit of these blockages.

One thing I would recommend after either yourself cleaning the carb or even a shop if you are not 100% sure of their abilities is to plug a voltmeter into a recepticle when you get it back running prior to turning on any electrical equipment.  I have seem too many audio/video components and electrical devices get damaged from someone not knowing what they are doing with a generator carburetor.  Generators need to be set to voltage and frequency not RPM like most other small engines.

I generally set the carburetor to produce about 125-128 volts and approx. 62-63 Hertz under a no load condition.  When you apply load it will pull the voltage and frequency down somewhat and usually right on the money, about 120-123 volts and 60 Hertz.

Mike.

 

[Macrosill]

Hello all,

I have just been told by the RV sevice place that my carb on the generator needs to be replaced again from last year because it sat too long and the fuel gummed up the jets.  He recommends that we run the generator once a month to keep this from happing.  Any thoughts or suggestions.

Thank you in advance,

Sean

Try running the genny with some fresh gas and Seafoam additive.  I used it on my genny a couple weeks ago and it worked great.  The genny had sat for 2 years with the previous owner.  It would have a hard time starting but would eventually start, idle rough and not be able to keep running under a load.  I bought some fuel line, placed some fresh gas in a 2 gallon gas can and ran the fuel line from the fuel filter to the gas can.  After running for about 30 minutes the idle smoothed out and after a few hours running for a couple days she runs fine under a load from the A/C. 

 

[grayboy]

I HAD THE SAME PROBLEM WITH MY GENERAC GENERATOR 6500 WATT. THE RV OUTFIT TOLD ME THEY DON'T REBUILT CARBURATORS BECAUSE THEY CAN'T BE TOTALLY REBUILT. HIS PRICE WAS $600 TO REPLACE. I SPENT MANY HOURS ON LINE TRYING TO FIND MY JAPANEESE NIKKI CARBURATOR WITH NO RESULTS. I FINALLY E-MAIL CHINO MOWER IN CHINO, CA. THEY HAD A REPLACEMENT FOR $143 AND WOULD TAKE 2 WEEKS TO GET IT. I TOOK THE OLD CARB AND SOLINOID IN TO MAKE SURE IT WAS THE RIGHT ONE. WHILE THERE THE OWNERS SON TOOK THE SOLINIOD OFF AND FOUND IT WAS STUCK, HE MESSED WITH IT FOR ABOUT 5 MINUTES AND GAVE IT BACK TO BE AND SAID, BEFORE YOU BUY A NEW CARB, PUT IT BACK ON AND SEE IF IT WORKS NOW. I REINSTALLED THE CARB IN 5 MINUTES AND THE GENERATOR RUNS GREAT NOW. I ALSO CLEANED IT BY SQUIRTING CARB CLEANER THRU EVERY HOLE I COULD FIND, SOME AT MY AGE ARE HARD TO SEE, SO IF YOU HAVE A YOUNG SON OR FRIEND HELP YOU IT MIGHT HELP. SO ANYWAYS, INSTEAD OF $600, IT COST ME $18 FOR MOWER SERVICE TO MY RV GENERATOR .

JEB "GRAYBOY"