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Old 03-03-2018, 09:15 PM   #1
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Default Onan 2800 Microlite Runs great then randomly surges then dies...

My Onan 2800 Microlite is running erratically. It will idle fine for hours, and sometimes it will run great under a load, but sometimes it will randomly start surging and die {always under a load} for no apparent reason. There is no pattern to this. I wish there was. We are at 40 feet above sea level and it is hot and humid, and I am wondering about removing the "sea level" adjustment and adjusting it lower, or richer, as mentioned on some other posts. I have run Seafoam through the system directly at a 50/50 mix. I don't think it is the carb.

Any ideas ? Thanks, John
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Old 03-04-2018, 12:19 AM   #2
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.

Google for the red rover's onan trouble shooting guide.

it is a free download.
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Old 03-04-2018, 01:15 AM   #3
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Stay away from seafoam as it will create a huge pile of white smoke and muck things up.

Get some carb cleaner with the unit running spray some down the carb in various areas slowly as not to kill it while it is idling. Or if the unit is already warmed then spray some down the carb and wait a while to restart.

My onan 4000 with low hours would sometimes go into dipsh?? mode and idle up and down.

Treat this onan System like a carburetor vehicle of the past. After I spray the carb it purrs like a kitten.

If you got old oil in then its a good time to change it to remove all the gum resin out. But if oil is still newer then don't worry. Onans are tougher then they get credit for. Hope this helps.
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Old 03-04-2018, 02:17 AM   #4
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My bet is the fuel pump is about to fail. Just a guess. Replace it and all will be well. It (fuel pump)runs erratically when hot. I have failed three of them.
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Old 03-04-2018, 02:32 PM   #5
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Default Thank you for your responses !

I think I will try the non-Seafoam carb cleaner first since it is the simplest solution, but also realize that repairs like this are rarely that simple. I hope so.

If that doesn't work then the fuel pump is next. There is not a lot of room in my Onan Microlite 2800. I assume the fuel pump is in the back under the air cleaner from watching videos on replacing the fuel pump on other Onan's. I cannot find a video that is specific to the 2800 Microlite.

Can anyone offer any tips on replacing the fuel pump on a 2800 Microlite that is hanging under the back of my Roadtrek ? I can reach the access panel easily from underneath. (I have spent a lot of time down there already...), but I am wondering how to access the fuel pump and hoping it can be done without removing the generator.

Any insight will be appreciated. Thanks in advance, John
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Old 03-04-2018, 02:48 PM   #6
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I would second the possibility of the fuel pump being an the way out, but that is far from certainly the cause. It is likely not a plugged up carb as it runs OK for quite a while before the issues.

As to whether or not to use Seafoam, I would be afraid of it at all. It has been effectively used by dozens and dozens, probably hundreds of class B Onan owners over the years with great results. Spray cleaners and Seafoam are good for different issues. The spray works well when you have venturi and other orifice plugging in the airstream area, Seafoam is what will melt out the gelling in the tiny fuel passages within the carb wet areas. Personally, I have never heard of anyone saying that Seafoam messed things up.
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Old 03-04-2018, 02:57 PM   #7
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Try loosening your gas cap. worked for me.
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Old 03-04-2018, 03:17 PM   #8
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Default Thanks again for your responses ideas !

I found one site online that says the 2800 genset must be removed from the Roadtrek to replace the fuel pump and another site that states that there is an access panel under the genset that can be removed to access the fuel pump.

Can anyone confirm any of this info if it comes down the replacing the fuel pump ?
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Old 03-04-2018, 03:31 PM   #9
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I've replaced three Onan 2800 fuel pumps. There is no access panel and the unit must be removed from the Roadtrek. Have fun!

Airtex sells one cheaper than Cummins Onan.
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Old 03-04-2018, 03:37 PM   #10
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Okay. Thank you. The truth sometimes hurts ! I guess pulling the generator down is not that big of deal once you have done it once or twice. Is there anything I should know about lowering the genset ?
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Old 03-04-2018, 03:41 PM   #11
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Okay. Thank you. The truth sometimes hurts ! I guess pulling the generator down is not that big of deal once you have done it once or twice. Is there anything I should know about lowering the genset ?
Yep. The AC line goes up through the floor to the transfer switch without a break. Start by removing that line and pulling it through the floor.

Disconnect the battery. There is no fuse on that line and you don't want to do some DC welding.

It is worth checking fuel tank vacuum causing the problem.
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Old 03-04-2018, 04:02 PM   #12
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Thank you. By AC line do you mean the output feed line from the generator into the RV ? Can you tell me where that is found inside the RV so I can unhook it first ? We have a 2007 Roadtrek 210. I realize it could located in different locations on different models. Would it unplug from the invertor ? Thanks again.
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Old 03-04-2018, 06:00 PM   #13
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I Have a 190. It goes to the transfer switch which is usually located on the back of the circuit breaker box. There is no connector. It is probably connected by wire nuts.

Dropping the generator is not a trivial task but you will get it figured out. The charge to R and R the generator is $200-$300. To have the repair done by a vendor is probably a $600 charge so it is worth your effort to give it a go. Second time is much easier, as is the fifth! Some of us put in a junction box for the AC line so we don't have to tear apart the interior..
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Old 03-04-2018, 09:07 PM   #14
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Seafoam is a hydrocarbon blend AKA (petroleum distillates) with isopropanol AKA (Rubbing Alcohol.

Gumout Jet Spray Carburator & Choke cleaner is usually a blend of Kerosene and Toluene.

Each product has a specific purpose and effectiveness. Plus these are just two popular brands that people have years gone to.

Now in the professional world their is at times better products and product delivery systems available. As well as products marketed for a wallet flush.

My experience has been most successful with small and large engine carburetors using products like Gumout for exterior and interior of removing dust, dirt and grime along with all that black sticky stuff plugging up the ports, plates and tiny orfice holes. As when on contact the solution uplifts the dirt and grime quickly and very efficiently plus dries almost instantly.

Other products that you may use don't work the same as they generally don't remove the residue fast enough unless you use with some type of air pressure. Plus the formula dissipates very slowly leaving the bulk of the residue in the carburator and the intake manifold. Which can result out in fouling out the spark plugs and other key components down the path of the carburetor because it just simply is not the correct product to use.

But I swear my car runs better etc. etc. etc. and in most cases that is true to a point but in some cases cars have been towed to the shop too. But to be honest these products are used incorrectly and lets not forget to mention even better products to use are available.

Alot of products have been dummed down due to the protective coatings on fuel injection components since they have a layer of teflon type coating.

As I mentioned most products can be effective but at what cost to the engine and longevity. One day at a new shop we acquired they didn't have the proper fuel injection cleaner as they used Seafoam. I was curious as I observed and participated in the fuel injection service on a used car. Well the results were minimal at an idle as not much came out of the tail pipe and it sucked down the allotted cleaner in no time compared to the professional products we used that would allow some smoke which was more of a brown in color.

Well when the tech took the car out a Ford Mustang for a test drive after servicing with Seafaom. He took a right turn to pass the front of our store a big huge amount of smoke covered the whole street and our store where we couldn't even see out the windows. Well the cleaner caused this as it found a pocket most likely in the intake somewhere and at a higher throttle driving it flooded the chambers of the pistons. Seafoam failed because it is a cheap alternative to the real cleaners out their available.

Now lets distinguish the two types of cleaners for the carb and for the rest of the engine such as the valves, piston tops etc. Carburetors and choke cleaners are used to clean the external and internal of carburetors. Other fuel cleaners are used for the injectors, piston tops and the valves etc. A once size fits all version doesn't exist at this time as they need to be different formulas.

The brand I recommend for carburetors is just about any carb cleaner on the shelves that dissolves quickly and cleans well visually.

The best consumer brand to clean the injectors, valves and tops of pistons is the propitiatory ingredients in techron PEA (polyether amine). Now I won't begin the debate on gasoline additives at this time as thats a different subject.

The professional brand is Motorvac which often requires a machine or equipment to properly to a fuel injection and carbon clean service. All other contenders are just that contenders and the results are inferior.

However they are now offering the cleaner to be purchased outside the typical case purchase only often at a Napa Store or a supplier which is available in a little yellow bottle.

Now they offer different version of equipment and cleaners as I can't speak for those items.

I can speak for the full size machine where we dilute fuel with the cleaner and use a sequence of areas such as the fuel line, injector rail and then directly to to the pistons with the vehicle running generally atleast a few hours to complete the service.

I have been amazed at how we have saved engines from being torn down to be rebuilt just by using this cleaner and machine. Service is alittle spendy but I have gained a ton of customers because of it.

Hope this helps as I realize everyone has their own way and success and I thought I would share my experience. Thanks
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Old 03-04-2018, 09:22 PM   #15
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All very well stated, but doesn't address the major issues with the Onan 2800 carbs, which is tiny fuel passages, mainly since the mid 2000s, which appear to be meant to restrict fuel for emissions reasons and overide a jet or mixture screw setting to the low side. They are so small that fuel gels in them and blocks them, in as little as 3 weeks with ethanol laced gas. Seafoam has been proven over and over to clean the gell out very well and prevent it in storage. Some others have been used, particularly the BG products, successfully, also.

My point was, and is, that Seafoam works for the major issue affecting the Onan 2800 carbs and has saved owners many thousands of dollars over the years. Telling folks it is not a good product and causes damage, I think, is just not backed up by the history we have all seen. Are there better products for this issue? maybe. But that doesn't detract from the fact that the Seafoam works very well for nearly everyone that is currently running a 2800 Onan, and has prevented a awful lot of new carb replacements being made.
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Old 03-04-2018, 09:39 PM   #16
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Default The Verdict...

Thank you for everyone's input. I have learned a great deal. Today I started the generator and let it run for a while. It ran fine, then I turned on the A/C and put in under a load. Within 10 minutes the motor started to surge, get progressively worse, and then stop. I crawled back under the RV and pulled off the fuel line to the carb and put it into a clear glass bottle. I hit the remote starter button under the RV repeatedly and NO FUEL CAME OUT. Then after about 5 minutes of cooling down it was pumping fuel again. I don't think there is any doubt that I have a fuel pump problem. Thanks again for everyone's help.

Dropping that generator will be new experience for me....unless someone can recommend a good generator/RV shop near Inverness, FL.
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Old 03-04-2018, 09:48 PM   #17
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I used my HF motorcycle lift for anything heavy to be mounted under either a trailer or a vehicle. They used to be much lees expensive. I have the older version of this one https://www.harborfreight.com/1500-l...ift-63397.html
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Old 03-04-2018, 09:53 PM   #18
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I use a cheap scissors style transmission jack with a piece of plywood bolted to the top. I think they are still under $100 and you could also just rent one.
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Old 03-04-2018, 10:33 PM   #19
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Quote:
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Okay. Thank you. The truth sometimes hurts ! I guess pulling the generator down is not that big of deal once you have done it once or twice. Is there anything I should know about lowering the genset ?
Yes, remember that gravity is a bitch. Seriously, requiring this for simple service has to be one of the biggest unfunny jokes ever perpetrated on the Class B fraternity.
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Old 03-04-2018, 11:07 PM   #20
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Yes, A 50.00 part that takes 15 minutes to physically switch out, but takes 4 hours (or more since it is my first attempt) to remove the generator in order to access the part and put it back. A little access panel would make a lot of sense. Thanks again.
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