Coughing, Choking, Fouling, Rough Running Onan Generator

[Chocoholic]

Sent: 1/12/2005

well suppose it was my turn for some genset events, on a recent trip to lake started the generator up and it started the smoking , choking down , and irregular run syndrome as well as fouling the new spark plugs etc.. then a few days later took the oil cap off and it was over flowing with oil and the smell of raw gas...so drained the oil and filter also put in some cheap oil to run when ready to get it cleaned out and flushed etc.. so started by taking the carb off and apart thinking it may of been sticking carb float etc, use either spray makes good carb cleaner.. reassembled and then off with the heads and cleaned the carbon off the heads and valves ..piston etc.. then tried it varoom!!! smoked a few min then purred.... there wasn't any gunk in the carb and all looked fine but apparently there was something that caused the bad running in the beginning...and thought id pass this info along.... 

[tiinytina]

hi ho,
   cranked up the Genny on the way from my dad's farm to the house to load her up... Genny cranked right up and when running to to snuff cranked on the roof ac. First 2 times I did this I didn't make it out of the farm drive (0.25 mile) before the genny coughed, sputtered and died after not quite running smoothly. > Third time was the charm.  :angel:Genny ran smooth for about an hour for most of the drive to Goose Bay with the AC unit cranked on.  Then it coughed sputtered and died, then refused to restart.  Checked and added oil (a bit low) saturday. Restarted it today at home so I could vacuum and clean. It ran fine and got the vacuuming done. The minute I cranked the AC on... it coughed sputtered and choked out. It cranked up fine and ran the AC unit on fan only fine, adding the compressor to the load choked it out.... >  I have an 80 gallon fuel tank and it was more than half full. There was Stabil in this load of gas about 1/2 strength.

I am planning on giving it a full oil change with filter and replacing the spark plug and fuel filter. I'm thinking its fuel related and probably the fuel filter (probably original with 850hrs on the genset)... if anyone can add anything to my grocery list please do.

I have an Onan- 4QBGE-1987 vintage.

Thanks!
Tina

[Chuck]

I had on my agenda this weekend to rebuild the carburetor on my Onan generator.  Since I bought it I the unit would not run but for a short time and I was pretty sure that this was due to gas deposits in the carb.  With so many other problems going on with the RV and understanding that the 50+ gallons of gasoline that were in her at purchase were going to sit up and get stale, I bought a 32oz bottle of Sta-bil brand stabilizer and poured it all in there.  This is all that I can attribute to the generator starting up and idling properly after 30 days of sitting up with stabilizer in her bowl.  Before, it would run until the choke kicked off and then start hunting.  

There must be something in the stabilizer that actually helps to break down the deposits already in there, though I have always heard that it would only keep old gas from getting any worse.  Anyway, it's a small investment compared to the time and trouble of rebuilding a carburetor...may be something to consider doing between camping events.

Peace  ^RokOn^

Chuck

[tiinytina]

Spent a week online attempting to find parts for my genny... Figures that they changed a few things on my model genny on 09/1987 from previous versions.... no clue if mine is a before or after... The oil, air and fuel filter on the unit were not Onan brand so no numbers matched up...  yea Queenstown RV.... actually had a card with all the parts listed... So... $72 later.... new air filter, new fuel filter though the inlet and outlet size was smaller... (I really cranked down on the clamps and it doesn't seem to be leaking), and changed the oil. Can't seem to find anything that tells me how many quarts it uses. My Queenstown dude said 2... so thats what I bought and it didn't come close to filling it. So it now has 2 qt onan SAE30 and 1 qt Mobile 1 5wSAE30....

Cranked it up and hit the AC on a few times and it has yet to die out... yea. I didn't change out the plugs though I bought 2 new ones. I need to find the gap distance specs which, so far... can't find.  And I tend to follow the addage that if it ain't broke don't fix it...  so I think I'll save them....

I'm taking her in to get her new awning monday so I'll run the genny for the trip and see how she does... may have the "professionals" take a gander if she acts up...

Tina

[colofarmboy]

One thing to keep in mind, Stabil is meant for static storage. It works by forming a film on top of the gas, "preserving" it for storage.  Moving the tank, running the engine, etc moves this film and then Stabil is no longer useful.  Seafoam works by actually mixing with the gas, thus is useful for "preserving" gas in less used (but still used) applications.

Kind of off topic of your post, but a comment that might have some bearing none-the-less...

[tiinytina]

Actually just bought a can of SeaFoam to toss into my friends rough running diesel tractor, was reading the label and the lightbulb went off to use it in the rig.... I also didn't know about the uselessness of stabil after mixing... thanks!

Tina

[tiinytina]

ok - tune up, new oil, new filter, new gas line filter, air filter... starts right up runs everything... kick on the AC... conks out....  restart genny, wait until it smooths out, kick on AC... conk.... repeat... runs fine after that. Wondering if it may be the AC compressor?

Tina

[tiinytina]

On this issue Wonder Brad advanced the idle a tad, and voila!
Tina