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  • #16
    Originally posted by familytruckster4 View Post

    There are several discrepancies from the Youtube video and whats actually in the Cummins/Onan manual.on page 3-3 https://www.cummins.com/sites/defaul.../0981-0159.pdf
    Nowhere does it describe the scenario of running it 30 mins and waiting 6-7 hrs. It also says to fill the oil to the full mark, not what the Youtuber says. And oh BTW, oil does not "expand"
    He also states that 15w40 is only for diesels when the graph on 1-5 shows that 15w40 actually offers the widest temperature range of service. Most modern 15w40 oils such as Mobil Delvac 1300 or Shell Rotella also carry the ratings for use in spark ignited engine (gasoline or LP)
    Like so many other cases of Youtubers its big on advice from a guy thats just another RV owner, I prefer the manuals.

    Also note that page 1-4 shows the fuel must be minimum 87 octane, indicating that it will run on 87. I would however be diligent about not using some of the "super88" octane thats out there right now since this contains 15% ethanol and the vast majority of small engines are not designed for anything more than 10%
    Thanks for the education. Anything that is hot will expand. Think of your radiator expansion tank as an example. Youtube is a great resource but to your point its not always perfect. The point I wanted to make was to check the oil after a short run and soak and with the dip stick screwed all the way in. Since components in the engine are coated with oil where one that sits over winter could show a different level running then letting the unit soak is reasonable. Experience with my dads generac is that oil level and level of the rig is critical on generators. Its always best to read the owners manual if one is available.

    I also completely agree in running Rec fuel unless the generator is used often. I run Rec fuel in my generator as well.

    Jim
    Last edited by MidwestCamper; 06-22-2022, 06:30 PM.
    2017 Imagine 2600RB
    2015 GMC Sierra 4x4

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    • #17
      Originally posted by RoyB View Post
      I am not sure what octane the Onan is designed to run at. I have been putting 91 in this weekend (highest avail). It's 100 degrees out and I am working it hard running the AC all day. I like to run higher octane in extreme heat to reduce any chance of detonation. It's not that out of level. about 1/4 degree both ways.

      The generator ran for a good 12 hours yesterday. It shut down right before I Got back last night since it was still cool inside. It was about 1/4 tank. I went and threw another 5 gallons in and it ran all night without a problem. Put another 5 in this morning. It seems to be using about a .8-1 gal an hour with the AC running all day. I set the temp a little warmer today. Probably don't need to keep it at 72 when I am not in it. The good news is the system will maintain 72 off the generator in 100 degree full sunlight. I think it cycles between the 3 of them so the generator isn't overloaded.

      I will change the plug and filter when I get back. Also keep a spare filter on board as well. I appreciate he help everyone!
      RoyB Running an octane that is higher than recommended will drive more heat since the effective ignition timing will be retarded. Premium fuel will result in later ignition phasing than regular which most likely your generator is made to run on. Just my 2 cents. There may also be an altitude adjustment knob on that unit. But it seems your leveling the rig has made a positive change. Premium has no more fuel system cleaning properties than low octane fuel.

      Jim
      2017 Imagine 2600RB
      2015 GMC Sierra 4x4

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      • #18
        MidwestCamper Jim, I personally have had decent luck with running 1-2 tanks of higher octane fuel just to break up or soften some of the deposits in the bowl faster. Regular fuel will do the same thing, just takes longer.

        Sounds like the OP's generator is getting better. Probably needed to be ran and have the fuel in the cell cycled out.

        I suggest some form of stabilizer in the tank and if you can find it ethanol free fuel. Ethanol fuels can separate out, which leads to running issues, it also absorbs moisture.
        Joseph
        Tow
        Vehicle: 2018 GMC K2500 Denali Diesel
        Coach: 303RLS Delivered March 5, 2021
        South of Houston Texas

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        • #19
          An advantage to running premium fuel is that it usually has less (or sometimes no) ethanol. I used to run premium in my boat (two engines and a generator) for this purpose. I learned the hard way that fuel with ethanol, even with ethanol stabilizer, would foul the carburetors . . . and I had 7 of them to clean (three per engine and one for the generator).

          You can research online for which brands of fuel in your area have ethanol free (usually) premium fuel.

          Rob
          Cate & Rob
          (with Border Collies Molly & Angel)
          2015 Reflection 303RLS
          2022 F350 Diesel CC SB SRW Lariat
          Bayham, Ontario, Canada

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          • #20
            Typical premium in MI has the same amount of ethanol as regular (for now 10%) around here they refer to ethanol free fuel as "rec fuel" and it is 89 octane and usually at least $1 more per gallon than regular. I know some of the verbiage changes regionally. On our trip to Iowa last year I noticed "super 88" fuel at the pumps with little explanation as to what it was. I eventually determined that it was 15% ethanol. I thought it was very poorly defined on the pumps. The ironic part was that in the heart of corn country their ethanol free fuel was only about 45 cents a gallon more than 87 regular.
            Seems like fueling is a learning experience these days
            Last edited by familytruckster4; 06-23-2022, 06:55 AM.
            2021 Reflection 337RLS, 2021 Silverado 3500HD 6.6 gas. Nellie the wonder boxer

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            • #21
              Fella's,

              All fuels here in the US for road usage is E10. Marine fuel here are either E0 or treated to prevent phase separation and corrosion in the marine environment. Recreation fuel here is typically 89 to 93 octane and is also primarily used here for the marine market or for those that have items such as Stihl saws that need E0 or older equipment that is not compatible with Ethanol. There is no leaded fuel here.
              We have a fuels lab at GM where I had witnessed testing of fuels years ago many times. We would purchase special lab grade fuels at extremely high prices to keep the fuel as consistent as possible. We also had what is referred to as high DI (distillation index) fuel to calibrate engines on less than desirable fuels that could cause startability issues. So a few things from these folks have been shared over the years on fuel.

              Calibration on both premium as well as to a lower octane fuel in order to achieve engine protection on fuels that could induce knock was a daily practice on performance cars. The verbiage can be tricky between premium recommended or premium required. This verbiage has two completely different meanings. Same as regular recommended.

              Running premium in an engine calibrated solely to regular fuel is a waste of money. Some engines can learn the knock system on higher octane fuels to advance the ignition timing. These engines will be described in the owners manual with verbiage that increased performance can be had on higher octane fuels and so on. A generator will not have these expensive feature where the manual will state which fuel to use. Most likely this is regular 87 grade. There could also be verbiage that the generator is 87 minimum. All this means is to never use fuels below 87 octane. Higher grade will actually produce less torque in these engines due to late combustion phasing form a slower burn rate of premium fuel. It will produce more heat, but generally premium will not do any harm so the minimum phrase is used where fuels below the minimum recommendation could create engine damage.

              All fuels contain additives to clean the fuel system where some may be marketed by a variety of catch phrases to make folks think the premium fuel has that extra cleaning capability. It does not.

              If you want to talk engines and powertrains and stay off topic, send me a PM and we can have an endless discussion on fuels, engines and powertrains. Its been my life for decades.

              Jim
              2017 Imagine 2600RB
              2015 GMC Sierra 4x4

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              • #22
                So the Onan is still giving me trouble. Went boondocking a couple weeks ago and couldn't get more than 30 minutes of continuous use. The last day it was cool in the morning and I needed to recharge our batteries since they were almost dead. It ran for 2 hours no problem, even under load (fire place). It was cool out though, 50 degrees. I did change the oil and fuel filter so I am thinking it's now the fuel pump. Tried to run it a couple additional times and it runs for a short while and then quits.

                Symptoms: Starts and runs fine. After 20-30 minutes (under load) it surges and dies.

                I have read of 4 main issues with these Generators.
                • Carb gets clogged from lack of use. If it runs for 30 minutes I can't see this being the issue.
                • Too much oil. I can't see a sensor causing the surging.
                • Generator sucking in too much hot air and overheating. This part will help re-direct hot air: PT# 026-00495 Air Discharge Vane-Side
                • Fuel pump. This makes the most sense at this venture. It seems to only die out when under load. In addition the surging and inability to re-start indicates a fuel issue (as does the code). Easiest way to check is see if any fuel is in the bowl. I suppose I could still do this since it didn't re-start it since the last shut-down.
                I am almost positive it's the fuel pump at this point.
                2020 GD 320G
                2021 Ram 3500 H.O. SRW.

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                • #23
                  RoyB Have you traced the fuel line? Is it possible (short term) to use an auxiliary fuel cell say from a boat to determine if it's a fuel supply issue?

                  I have a portable generator that was giving me an issue. I changed from the factory fuel filter (it broke) to a generic paper filter and it caused issues as the generic paper was more restrictive forcing the fuel to vaporize across the element leading to starving of fuel. I did not consider that making the fuel line 4" longer and the paper filter (fuel tank above filter so gravity feed) would lead to a vapor situation on the outlet side of the filter causing surge, popping (misfire from lack of fuel) and all around performance issues.

                  Back many many moons ago, first MH parents had was having a strange issue with the generator (we rarely used it). Both he MH and the Generator were having issues so Oldest brother and dad decided to add a lift pump at the tank to help (MH was having powering issues). Upon firing up the lift pump, fuel system leaks became evident. Fuel supply line to generator was leaking at both ends and hose was internally collapsed. Fuel line to engine had a weak spot that let go. And the big kicker, someone used a non fuel rated Tee to split the fuel line to the generator off of the main line going to the engine. This Tee internally swelled to the point the 1/4" passage was less than 1/8" (probably close to 1/16") and finally cracked. Since the entire system was suction, everything was pulling AIR, that lead to starting and running issues with the generator and engine, reduce engine power (carb starved for fuel), and filter issues because basically the fuel line was a vacuum cleaner of dust from under the camper.


                  Sorry for the long story explanations, but it helps to understand why the odd questions and hopefully triggers or points you to a solution.
                  Joseph
                  Tow
                  Vehicle: 2018 GMC K2500 Denali Diesel
                  Coach: 303RLS Delivered March 5, 2021
                  South of Houston Texas

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                  • #24
                    Without confirming fuel pressure (which could be done with a gauge) I would lean towards it needing a carb kit and a good cleaning. while its apart. It could be the dirty carb causing it to run lean or rich and the unit shutting down due to that.
                    This guess was made taking into account the history of the unit.

                    I had a portable Generac 2000w inverter gen that would run well for 15 minutes and then suddenly shut down, it then progressed to it shutting down when anything other than a minor load was put on it. In the end it turned out to be the potted control board and it was sold for parts because a new one cost more than the board.
                    2021 Reflection 337RLS, 2021 Silverado 3500HD 6.6 gas. Nellie the wonder boxer

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                    • #25
                      My guess is fuel pump. I've been following a lot these issues on various different forums. The problem is see, as well as other, is it's a long draw for the fuel pump versus pushing the fuel. When you draw that far away it could be a host of issues; weak fuel pump, collapsing fuel line, on and on. If you push the fuel, you eliminate many of those problems, which folks have done.

                      I'm with you, if you can get it to run 30 minutes to 2 hours, it's likely not a carb problem.
                      Curtis, Christine, Cole, and Charlotte
                      2007 Chevrolet Silverado Duramax LBZ, CCLB
                      2020 Momentum 351M
                      2004 Essex Vortex

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                      • #26
                        Originally posted by OffToHavasu View Post
                        My guess is fuel pump. I've been following a lot these issues on various different forums. The problem is see, as well as other, is it's a long draw for the fuel pump versus pushing the fuel. When you draw that far away it could be a host of issues; weak fuel pump, collapsing fuel line, on and on. If you push the fuel, you eliminate many of those problems, which folks have done.

                        I'm with you, if you can get it to run 30 minutes to 2 hours, it's likely not a carb problem.
                        Do you know if you can run 2 pumps? Is it possible to have too much pressure? I would just add one at the rear and keep the front one.
                        2020 GD 320G
                        2021 Ram 3500 H.O. SRW.

                        Comment


                        • #27
                          You might need to check to see if the front pump is a "flow through" design. If the pump on the generator is flow through, you could disconnect it and leave it there. Either way you could put a pressure switch on the rear pump so that it will shut off as XX psi or use one with a low pressure output. You are more worried about pushing fuel to the generator.


                          If you have too much pressure, it's possible that the float valve in the carburetor cannot stop the fuel flow.
                          Joseph
                          Tow
                          Vehicle: 2018 GMC K2500 Denali Diesel
                          Coach: 303RLS Delivered March 5, 2021
                          South of Houston Texas

                          Comment


                          • #28
                            We have experienced the same issue the OP described. Changed the filter, still died after a few minutes. Changed the fuel pump with an OEM one, ouch on the price of that!!! Same problem. Bought a $10 dollar low pressure 12V fuel pump off of Amazon and plumbed it at the outlet of the fuel tank. Spliced in the wiring for the second pump off of the original and haven't had a problem since.
                            Tim & Terri
                            2022 Grand Design Momentum 376THS
                            2018 Ram 3500 DRW Mega Cab

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                            • #29
                              The earlier Duramax HD trucks has a suction pump under the hood. Almost everyone I knew (including me) eventually installed a lift pump at the tank. The trucks ran better after. Theres a lot of issues with a pump trying to pull fuel, the slightest defect in the fuel line will adversely affect performance.
                              2021 Reflection 337RLS, 2021 Silverado 3500HD 6.6 gas. Nellie the wonder boxer

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                              • #30
                                A lift pump could help this situation if the fuel system is compromised but still, something is wrong where Onan would not have designed the generator to need a lift pump from day one. I would be tempted to understand the issue and correct it. A mighty vac pump could help to determine if air is entering the fuel system prior to the pump.

                                https://www.tooldiscounter.com/produ...1ddef2f0a8e686

                                Jim
                                2017 Imagine 2600RB
                                2015 GMC Sierra 4x4

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