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  • #31
    Break out the parts cannon...... LOL
    2021 Reflection 337RLS, 2021 Silverado 3500HD 6.6 gas. Nellie the wonder boxer

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    • #32
      I would think it's not Onan's issue as to how far the tank is from the generator. Onan may have a recommendation and with all of the variables in routing the fuel lines, it's possible that the line is 10% or more longer than intended. This 10% could be enough to create the issues.
      Joseph
      Tow
      Vehicle: 2018 GMC K2500 Denali Diesel
      Coach: 303RLS Delivered March 5, 2021
      South of Houston Texas

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      • #33
        Take it to an Onan dealer who can test the unit and make the repair. This one (hopefully) session will hopefully get the unit fixed without throwing parts at it. If it ran well when new and now does not, there is a problem that should not require a modification to the system.

        Jim
        2017 Imagine 2600RB
        2015 GMC Sierra 4x4

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        • #34
          It's not exactly easy to drag the whole trailer to an Onan dealer. I haven't thrown any parts at it yet, just basic maintenance- Oil change and fuel filter change since I was as the hours required. As for if it ran good when new, I have no idea. It only has 64 hours on it and I never ran it when it was brand new for more than 5-10 minutes at a time. Apparently I needed more run time for issues to show up. I have read about fuel pump issues and it appears the symptoms are the same as what I am experiencing. A $20 aftermarket fuel pump is cheaper than the fuel of even bringing the trailer somewhere. If it still doesn't work, I am in the electrical industry with availability to mobile generator techs. They are used to working on industrial generators so I need to find out if they can work on these baby ones . My money is on lack of fuel flow based on the surging I get.
          2020 GD 320G
          2021 Ram 3500 H.O. SRW.

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          • #35
            Would it be possible to run the generator from a fuel can close to the generator? Drop a fuel line from the inlet side into a fuel can and let run for a couple hours to see if it is indeed a fuel delivery problem.

            Brian
            Brian & Michelle
            2018 Reflection 29RS Oct.2017 build date, EMS-HW50C , Lippert Remote
            2015 Chevy 3500HD CC LB Duramax , Reese Elite 18K
            630 ah battery, Victron Multiplus 2, 800 watts solar

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            • #36
              I cracked the carb bleeder valve. A drop came out. The last time I ran it was last weekend and it died out again. I primed it, and started it. Turned it off and checked the bleeder again. Quite a bit came out this time. Carb was dry after it dies which indicates fuel delivery issue.

              I noticed that my pump number is #A047N929. rebel23 has a year newer, same model unit, and his number is A064S965 pump.

              Maybe the A047N929 isn't adequate for the 320G so they put in a revised pump.
              Attached Files
              2020 GD 320G
              2021 Ram 3500 H.O. SRW.

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              • #37
                RoyB Fuel pump could be just a revised part due to supply chain. Fuel bowl being dry makes me wonder if you are not having a back flow issue with fuel flowing back to the tank. Something like https://www.napaonline.com/en/p/DFPF...pressionRank=1 to prevent the fuel from flowing back down the line. Back flow could also be leading to air trapped in the line (partly due to the suction from the tank).
                Joseph
                Tow
                Vehicle: 2018 GMC K2500 Denali Diesel
                Coach: 303RLS Delivered March 5, 2021
                South of Houston Texas

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                • #38
                  Originally posted by RoyB View Post
                  I cracked the carb bleeder valve. A drop came out. The last time I ran it was last weekend and it died out again. I primed it, and started it. Turned it off and checked the bleeder again. Quite a bit came out this time. Carb was dry after it dies which indicates fuel delivery issue.

                  I noticed that my pump number is #A047N929. rebel23 has a year newer, same model unit, and his number is A064S965 pump.

                  Maybe the A047N929 isn't adequate for the 320G so they put in a revised pump.
                  RoyB

                  This test concludes that you do have a fuel delivery issue. I've also ran into issues years ago where an obstruction in the tank which at each run would find its way to the tank strainer. This would also cause this intermittent condition where it may be good to look for this issue first. Worked on a diesel truck long ago with this symptom and it turned out the be a shop rag in the saddle tank.
                  ​Sometimes these pumps when failing will begin to seize up when hot. For the price of a replacement pump based on your model it would be worth a try to replace the pump but its also important to change the filter since debris from a failing pump could have compromised the filter. I would not mix parts base on model numbers since some pumps may have different pressure ratings depending on application and the run from the tank.


                  https://www.amazon.com/Electric-Repl...2s9dHJ1ZQ&th=1

                  https://www.amazon.com/Cummins-Onan-...ve%2C81&sr=1-4

                  Jim
                  Last edited by MidwestCamper; 09-25-2022, 08:44 AM.
                  2017 Imagine 2600RB
                  2015 GMC Sierra 4x4

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                  • #39
                    One other thing Jim's reply just triggered. You may want to check the fuel pickup. I have seen one on a class 8 that was cracked. As long as it was running it would do OK (had some minor issues) but when stopped for overnight, was difficult to restart. Something as simple as a hose clamp that is not completely tight or other issue allowing air into the system can create hours of headaches.

                    Cheap inline pump is probably your best option at this point to try and figure out if it's a suction issue or an on generator pump.
                    Joseph
                    Tow
                    Vehicle: 2018 GMC K2500 Denali Diesel
                    Coach: 303RLS Delivered March 5, 2021
                    South of Houston Texas

                    Comment


                    • #40
                      Originally posted by RoyB View Post

                      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.
                      I'm pretty sure the Onan pump is a pass through pump. BUT you want low pressure. The floats on these carbs are very weak and they won't hold back higher pressure, and you'll start seeing different issues.
                      Curtis, Christine, Cole, and Charlotte
                      2007 Chevrolet Silverado Duramax LBZ, CCLB
                      2020 Momentum 351M
                      2004 Essex Vortex

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                      • #41
                        Just an update. I changed the fuel pump with a cheap amazon knockoff linked above. $20.

                        Ran the generator under load and all was going good until the 30 minute mark. Shut off again. Checked bleeder screw and bowl was dry.

                        Tried to prime and start; generator would not start.

                        Pulled the hose and hit the start button. Pressure of fuel seemed very good and good volume.

                        Hooked the hose back up and generator started and ran fine

                        Then I got to thinking it might be the Fuel cuttoff solenoid. However, from this thread: https://www.irv2.com/forums/f54/onan...id-456887.html It appears that I would still have fuel in the bowl should the sensor be bad. It appears to only limit the fuel into the needle? I do not have fuel in the bowl.

                        I did read how someone put one of these on: https://rockymountaingeneratorsupply...arge-Vane-Side which redirects the hot air. I put a box fan directing the hot air away from the generator intake and it ran for an hour under load. It ran fine the entire time and did not shut down.

                        While under the generator it looks like the cut-out is off by a couple inches which may or may not have an affect on air flow.

                        I will try it tomorrow under load and see if the box fan keeps it running again. If that fixes it I have to assume it's sucking in too much hot air and something is shutting the fuel off due to an overheat condition.
                        Attached Files
                        2020 GD 320G
                        2021 Ram 3500 H.O. SRW.

                        Comment


                        • #42
                          How odd...And I'm not disputing your finding, just that if that's indeed the case, that to shut down for overheating they shut down fuel instead of just "turning it off". Maybe their thought is if it's over heating it could still "diesel" if there's fuel in the system.

                          This is a head scratcher.
                          Curtis, Christine, Cole, and Charlotte
                          2007 Chevrolet Silverado Duramax LBZ, CCLB
                          2020 Momentum 351M
                          2004 Essex Vortex

                          Comment


                          • #43
                            Originally posted by OffToHavasu View Post
                            How odd...And I'm not disputing your finding, just that if that's indeed the case, that to shut down for overheating they shut down fuel instead of just "turning it off". Maybe their thought is if it's over heating it could still "diesel" if there's fuel in the system.

                            This is a head scratcher.
                            It's my understanding that the control board shuts the fuel pump off if there are issues. High/low oil, overheat, etc. It's also entirely possibly the pump is still overheating from the hot engine exhaust. Directing the hot air away could help that too. I honestly can't figure it out. In researching, the below have been solutions to other peoples generator running issues:
                            • Replaced the fuel pump. Even replacing a newly replaced fuel pump
                            • Replaced the fuel filter
                            • Replace/clean the carburetor
                            • Vapor lock
                            • Air entering gas lines
                            • Overheating
                            • Low oil sensor. Add more oil.
                            • High oil sensor. Remove oil.
                            • Bad control board
                            • Loose wire to fuel pump
                            • Loose 12V power to the generator
                            • Adjust the altitude knob
                            2020 GD 320G
                            2021 Ram 3500 H.O. SRW.

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                            • #44
                              Your findings will be interesting for sure.

                              I don't have a service manual, so it would be interesting to see where they take the engine temp from and what actual temp vs measured is.
                              Curtis, Christine, Cole, and Charlotte
                              2007 Chevrolet Silverado Duramax LBZ, CCLB
                              2020 Momentum 351M
                              2004 Essex Vortex

                              Comment


                              • #45
                                I think it may be the "vapor lock" condition. I would try the fan routine tomorrow and then turn the fan off to see if it shuts down in 30 minutes again. It may be that the line from the fuel pump to the filter/carburetor may getting hot enough to vaporize the fuel. You could check temps on the line while doing this as well. The interesting part is why would it start doing this at this time? no answer for that.

                                Brian
                                Brian & Michelle
                                2018 Reflection 29RS Oct.2017 build date, EMS-HW50C , Lippert Remote
                                2015 Chevy 3500HD CC LB Duramax , Reese Elite 18K
                                630 ah battery, Victron Multiplus 2, 800 watts solar

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