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Onan 5500 run issues

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  • MidwestCamper
    replied
    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

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  • familytruckster4
    replied
    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.

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  • Cate&Rob
    replied
    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

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  • Jlawles2
    replied
    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.

    Leave a comment:


  • MidwestCamper
    replied
    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

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  • MidwestCamper
    replied
    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.

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  • familytruckster4
    replied
    Originally posted by MidwestCamper View Post
    RoyB Oil level procedure is fairly specific on an Onan. If oil level is not correct and with the rig off level, the oil sensor could be shutting you down. Fuel issue seems to have been ruled out after being able to run up to 7 hours.

    https://www.youtube.com/watch?v=iZvkG7HJA9k

    https://thecampingadvisor.com/onan-generator-starts-then-shuts-down/#tab-con-4


    Jim
    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%
    Last edited by familytruckster4; 06-22-2022, 05:57 PM.

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  • RoyB
    replied
    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!

    Leave a comment:


  • MidwestCamper
    replied
    RoyB Oil level procedure is fairly specific on an Onan. If oil level is not correct and with the rig off level, the oil sensor could be shutting you down. Fuel issue seems to have been ruled out after being able to run up to 7 hours.

    https://www.youtube.com/watch?v=iZvkG7HJA9k

    https://thecampingadvisor.com/onan-generator-starts-then-shuts-down/#tab-con-4


    Jim
    Last edited by MidwestCamper; 06-22-2022, 07:22 AM.

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  • MidwestCamper
    replied
    Joseph,

    Premium fuel as a better cleaning agent is a myth. The only primary benefit of high octane fuel is that it contains a higher knock number (i.e. higher octane rating). Engines calibrated for regular will actually lose torque in using premium (slower burn rate) and will only cost the customer more money. Engines calibrated to premium fuel will make more torque since the ignition timing is more advanced and closer to a term referred to as MBT.

    Jim

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  • Jlawles2
    replied
    One other trick you can try to help you get by is to try a higher octane fuel. Higher octane fuels contain more chemicals that act as cleaning agents for old fuels.

    Fuel filter issues are hard to diagnose because a clogged filter will let the engine get enough fuel to fill the carb bowl (or fuel pump for injectors) and possibly run at low power requirements. As demand for fuel increases, the flow rate is restricted thus not allowing enough fuel to maintain proper air / fuel mixture to run.

    You can listen to the generator running and if it sounds like it misses a beat (not backfiring but just flat out miss) then recovers, you may have a fuel delivery issue. I have a generator that does that. Only thing I can figure is I changed from the factory screen to a true fuel filter and I could literally watch the filter drain of fuel and fill with vapor.

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  • familytruckster4
    replied
    Good news. I agree on the fuel issue.
    My personal opinion would be to use the Wix filter since its less than half the price of the Onan. We had at least a dozen gas gens at work that we serviced and we used the Wix or Baldwin on them and never had any issues. Same with the oil filters. If you can find a match in a Fram or a Wix I buy those for half of what the OEM's cost. My Kohler engine on my lawn tractor has a Bosch on it that was the same filter my Jeep wrangler used. The Bosch cost me $3 at Menards, the Kohler filter is around $11
    Best wishes
    Scott

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  • ncitro
    replied
    RoyB Glad it's running good, fingers crossed for you. My money would be on bad fuel as well, hopefully you finally got through it. If you're headed back to full hookup land after your hospital stay (hope everything works out okay there), I'd recommend burning off what's in the tank and filling it with ethanol free. Ideally you'd find a way to get the bottom 1/4 out of there as well. For stabilizing it, I've got a buddy that's a marine mechanic and her swears by the Mercury product. I chased bad fuel in my snowmobiles for years, tried Stabil, Seafoam, you name it. The Mercury stuff always performed for me. They've got three levels, a cleaner, a storage, and an combination of the two.

    http://www.mercurymarine.com/en/us/p...cts/fuel-care/

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  • RoyB
    replied
    Originally posted by familytruckster4 View Post
    Unless its a direct replacement part you may have trouble. I cant tell if the blue clamp is reusable or not, you may have to cut the rubber hose and replace the clamp. You may luck out of someone can cross reference the Onan number, Amazon showed a few generic options
    I see a Wix filter 33049 listed as a direct cross, O'Reilly carries Wix or you could try NAPA which sells Wix filters under NAPA part # 3049
    Make sure you get a new clamp also
    Well I might be in the clear. After filling the airbags up and raising the front a little, the generator seems to be running good again. 7 hours so far without a shut down. I'm leaning towards either the high oil switch, or it's enough out of level that the carb isn't happy? Or all the old fuel is now out of it and the fuel cleaner is doing it's thing.

    I will change the filter with oem when we get home if it stays running overnight. I was able to remove the upper hose with metal clamp and put the hose back on without taking the clamp off. I have some small one if it doesn't work.

    Fingers crossed it stays running.

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  • familytruckster4
    replied
    Unless its a direct replacement part you may have trouble. I cant tell if the blue clamp is reusable or not, you may have to cut the rubber hose and replace the clamp. You may luck out of someone can cross reference the Onan number, Amazon showed a few generic options
    I see a Wix filter 33049 listed as a direct cross, O'Reilly carries Wix or you could try NAPA which sells Wix filters under NAPA part # 3049
    Make sure you get a new clamp also

    Leave a comment:

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