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RobG
Mesa, AZ
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Joined: 03/25/2001
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Here's another issue I'm having besides my furnace... ![[emoticon]](http://www.rv.net/sharedcontent/cfb/images/smile.gif "smile")
My generator... an Onan Gold Marquis 5500, is blowing black smoke intermittently. It didn't run for the better part of six months because I'd fire it up, it'd run until it was time to produce a load, and then it'd die. I had a carb guy come out and look at it. He cleaned the carburetor and then decided I had a problem with the fuel line at the gas tank because it wasn't getting fuel. I paid him his $50 and he went his way.
I decided to test that theory by buying a gallon of gas and running my own line. So I pulled the line off the back of the Onan fuel pump and found it POURING gas out of it. Interesting, it shouldnt be doing that. So I reconnected it and fired up the generator and it ran fine. Turns out the gas cap was off.. I had removed it just recently to put some stabilizer in the tank (though I never did because I didn't find the bottle of it), but never screwed the cap all the way back on. So I'm assuming my gas camp has a bad vent and dumbass didn't figure that out.
So anyway... it ran, and ran fine for maybe a 90 sec to two minutes, then would blow black smoke for thirty seconds, then go back to normal again. This would happen non-stop. Figuring the gas was probably old, I pumped it all out (12 gallons worth) and then dumped in five gallons of fresh plus some water remover/stabilizer/etc stuff.
Fired it back up... runs exactly as before. 90 seconds of just fine followed by 30 seconds of lower RPM and black smoke. Then back to normal.
I'm guessing at this point maybe it's still just getting what's left of the bad gas in the bottom of the tank and the fuel line? It's had a total of maybe two hours of run time since the gas change.
BTW, when the generator is running, I put on the A/C and a space heater to provide a decent electrical load. It continues to produce power during the slow-down, but every now and then my UPS will bleep, indicating it's not happy with the power quality.
Thoughts?
Thanks!
2019 Arctic Fox 992 Truck Camper
2006 Keystone Raptor 3814SS 5th Wheel Toyhauler (live in it fulltime)
2005 Dodge RAM 3500 Quad Cab Dually 4x4 SLT 6sp
A quad, a few motorcycles, and a dog.
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midnightsadie
ohio
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Joined: 01/07/2008
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I think your carb has gunk in it, use that one gal can and mix up some sea foam, run 15min let sit one hour, and then run the whole gal of sea foam.
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DutchmenSport
Indiana
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Joined: 10/10/2006
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If the smoke is black, it's burning oil. If it blows white smoke, it's passing unburned gasoline vapor, meaning the gas is too rich.
Considering you are blowing black, tells me you have an oil leak that is mixing with the gas and firing and exhausting the black from the oil.
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RobG
Mesa, AZ
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Joined: 03/25/2001
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Wouldn't oil be blue smoke? Like when a car needs rings, you tend to see blue smoke because it's burning oil and gas.
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STBRetired
I-80 and I-55
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Joined: 11/23/2015
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Usually black smoke is a rich mixture. Are you sure the A/Cis operating correctly? It almost sounds like the compressor is failing to start and is cycling on the overload. That would put a large load on the genny, hence the lower RPM and black smoke as the governor pulls the carb wide open trying to keep the RPM up.Mine will do that when DW tries to run the A/C, microwave, induction top and coffee pot all at the same time.
Try running with just the heater and put a bowl of water in the microwave while the A/C s off.
1999 Newmar MACA 3796 F53 6.8L
2016 Ford Edge Sport
Roadmaster Sterling A/T with Brake Buddy Select
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gbopp
The Keystone State
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Joined: 08/03/2008
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I thought black smoke was a sign of running too rich. Blue/white smoke is burning oil.
I'm confused.(again) ![[emoticon]](http://www.rv.net/sharedcontent/cfb/images/scratchead.gif "scratchead")
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Lynnmor
Red Lion
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Joined: 07/16/2011
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Too rich, is the choke wide open?
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Sam Spade
North Central Florida
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Joined: 11/05/2015
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gbopp wrote:I thought black smoke was a sign of running too rich. Blue/white smoke is burning oil.
I'm confused.(again)
No it is not you who is confused.
Using BOTH the AC and the heater together might be putting too much load on it......but that may not be the only problem.
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rcmiller32
Western NY
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Joined: 06/15/2012
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Black smoke is from a to rich condition. Possible causes are choke that is not opening fully when warm or a carburetor float and needle seat that are not working properly. Check to see if the choke linkage is binding and free to move. We had a problem with ours not going to full choke and we would have to crank for a very long time to get started. Most likely carburetor has dirt and a sticky float.
2014 Coachmen Pursuit 31BDP
2016 Ford C-Max Energi
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SCClockDr
SC UpState
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Joined: 08/12/2006
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rcmiller32 wrote:Black smoke is from a to rich condition. Possible causes are choke that is not opening fully when warm or a carburetor float and needle seat that are not working properly. Check to see if the choke linkage is binding and free to move. We had a problem with ours not going to full choke and we would have to crank for a very long time to get started. Most likely carburetor has dirt and a sticky float.
DITTO on the checking the float/needle valve! I would add to check the air filter for oil blowback contamination as well.
Had an oily residue on ours and plenty of black smoke, removed the filter smoke went away. So I replaced & problem solved, now exercise more care filling the oil on oil changes.
George & Cathy
08 Titanium 28E33SA, XM, Honda EU 3000is, Trimetric, RotoChocks, LP Reg. Mod, 2 Gal Accum., WiFiRanger GO2/Mobile
04 Ram 3500 5.9 DRW, PAC PRXB E/B, 4" MBRP SS Exhaust, Gauges, Aux Tank/box, BrakeSmart.
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