Onan 5500 quits when over 95 degrees

[RoyB]

Originally Posted by Edonabike

It takes at least a 90 degree plus day for the problem to show up. So far we have not had that temperature to test it. Our spring travel plans were to Florida state parks and they were canceled so not sure when we will get to test it.

Hey, have you been able to test your gen mod fix? I just got mine out of camping world yesterday where they installed the Jayco mod including an air scoop underneath and changed the compartment door to a vented one. Your vent showed to be directed to the left of the coach but mine ended up pointed to the center (opposite yours). It did not work, on the way home at 88 degrees it quit at 30 minutes, before I made it home. I'm hoping mine was put on wrong and yours is working. Let me know, thanks.

[JudyB]

Tried to get my dealer to install the vented door... he insists this is not a Jayco mod and I would have to get one custom? !!! We’ve been traveling for 4 months now using non ethanol gas without issues until yesterday at 98 degrees, we couldn’t keep the Gen running! Or is the 4000 series but same issue.

[Mike-NM]

After reading everyone's threads and various posts on this generator stopping/overheating over the last month and having had this issue periodically in the past….. I just ignored the problem as I had not hit really hot weather for any extended driving time but then it started up when I hit Texas last Thursday. Weather was hot in the high 90’s. My 5,500-watt Onan Marquis Gold Genset would start running and then would just stop and then after several short runs would not start at all. Fault 36....My investigation and fix was the following:

I stopped at a loves truck stop looking for any shade that was possible first…. And there was none to be found. So had to deal with the heat as well when I got under the generator and took off the gas line connected to the filter. Gas was present in the line so vapor lock was not the issue… I then primed it while my finger was covering where the gas line was connected to the fuel filter and could hear the pump motor and could feel the slight suction pressure of the pump. So that was not the issue.

I then pushed the start button while my finger was covering the fuel filter gas input connection and the generator started ran a few seconds then died. No surprise there as I knew it would without the gas line connected. But that was not what I was looking for…. I wanted to see what the idle arm was doing when it died and that would tell me if I needed to change the location of the spring.

Bingo…..what I observed was that the spring that controlled the idle arm that had notches on it and the current placement of the hook on the spring was causing the arm to drop lower and the generator would die out. I changed the position of the spring in the notch by gently moving it with needle nose plyers to the next notch to the left where the arm would not drop and cause it to die out. That fixed my issue and I drove the rest of the day in the heat of Texas without any issues and ran two air conditioners simultaneously with any more stalls or fault codes.

I suspect that the heat causes the spring to relax or loosen and therefore the engine running and idle speed changes without warning. Therefore, my suggestion for a quick fix take the cover off get the genset get it running using the same technique described above if it will not start at all. If it does start watch the idle arm and if it drops and stalls there is your problem.

While running the generator and experimenting with the idle arm and spring hook location. My issue was resolved with just moving it one notch to the left. I had no more stalls or issues in that Texas heat.

[JFlightRisk]

Thanks for posting your findings. I bet they'll help others that are having a similar issue with heat related problems.

[Mike-NM]

Thank you... based on all the information out there in this forum and various other ones from oil levels, to heat shield, vent installations etc. and the fact that it does not appear in a shop environment. It had to be some anomaly that only occurs in the environment when it happens and would take eyes on it and to observe what is actually happening at the time the stalls occur. If that idle arm drops 1-2 millimeters it stall outs. Does not take much and those notches are approximately 1 1/2 millimeters apart.

[fizikpal]

Love this forum for info like this. I have not had the issue... we have yet to run the generator under those conditions but it is good to know that potential fix. thanks

[Mike-NM]

As an update my return trip of 750 miles back to New Mexico and overnighting in Lubbock. I had no issues along the way. Heat was in the mid to low 90's. When I got back to higher elevation of New Mexico I placed the spring back in the original notch and the coach is now sitting in front of my house 89 degrees outside, generator running with both air conditioners going and frig. with no issues. My thoughts are... if it is not the gas being below a qtr. of a tank, the oil levels are adequate, fuel filter is good, the fuel pump is good (if you hear a clacking noise it is bad....should hear a low bass rumble noise and you can observe the fuel hose slightly jerk and slightly shake while priming when pressing the primer button If it is a bad pump replace it for 29.00 and do it yourself easy replacement) then it may be just an easy fix of moving it one notch.

[dpa4747]

I had the same problem....so here is what I think when you are going down the road the 200 degree heat from the trucks radiator is being pushed under the truck, that super hot air is what the generator has to suck up to cool.....so it might not be able to cool down while driving sucking in 150+ degree air

mine can run all day at 115 degrees while parked but when moving it really does not like it or the hot intake air

[Bluedog8117]

Hi All - I have a 2020 Greyhawk with an Onan 4K just behind the engine on the driver side. My issue is shutdowns when 95 degrees plus. Does not matter if driving or stopped, all that seems to matter is the ambient temperature. Like many on this thread, I am getting no help from Jayco or Cummins. Everyone points fingers and says "we can't replicate, nothing we can do." This is because we are in San Diego and not Vegas in the summer.

Anyway, I found the you tube video about oil levels. I do recall when checking my oil it was WAY high. Like almost leaking out when I unscrew the dip-stick. Didn't think twice about it! (Hey, it was at the fill line, right? )

Picking up my rig from the service center tomorrow. I am VERY hopeful about the oil level fix. Won't be able to test it until next summer.

Question: How many on here have had the issue fixed by taking out some oil?

Thanks!!!

[JudyB]

Taking off a half pint initially worked, but problem returned. Ran non ethanol gas all summer and that helped a lot, but..it returned. Placing drivers side in shade also helped, but recent post by Mike-NM above proposes a Different approach which we are going to in investigate.

[Bluedog8117]

Thanks JudyB. I saw that fix as well. We will follow in your footsteps and start with the oil first I think. Unfortunately we won't be able to know if it works until next summer! I am in a frustrating email exchange with Jayco. They basically say if they can't replicate at the service center, we are out of luck. They have very little sympathy for the situation. I think they are selling RV's so fast they just don't care!

[Mike-NM]

Ok... folks a little update.... I drove from New Mexico to Anderson SC. my generator started stopping again. I checked the fuel line no gas... so I got under the RV and traced the fuel line..... guess what I found... fuel line followed the generator gray power line along the beam toward the front of the coach and ran right underneath the grey water tank. The line was pinched along side the beam and when the gray water tank got to a certain level it eventually pinched the line closed. I suspect that when I dump it releases the pinch just enough to allow gas to flow. I was able to push up on the tank which was difficult due to the weight and not dumping it but was able to get that line free and pushed out from under the tank. The generator then had fuel and it started right up..... So trace that line and see if that is what is causing the issue. If you dump the tank there is no downward pressure as the day goes by and the tanks slowly fills then the pressure increases until it completely cuts off the gas supply.

[burtdahurt]

I am glad I stumbled on this thread. I have been battling with these exact issues with our 2020 34g vision xl. On the highway , the onan will shut off and throw an overheating code. After having an onan tech come out to the rv dealership and not finding anything wrong, I emailed and called jayco, they agreed to install a "vented" genset door. Since it's just getting hot here in phoenix, I will be testing out the fix here this next week. I will update my findings here.



Robb

[mkassab]

I just added my own vents.... here's my link: https://www.jaycoowners.com/forums/f...34g-81805.html

Pls send a picture and post .... I'd love to see Jayco's solution.

Thx Mark

[Jopopsy]

I wonder if the generator's position on the coach's frame relative to the heat coming off the engine and the exhaust has something to do w/ the overheating? Meaning, for those with a genset closer to in between both heat sources, I wonder if this still happens?

[mkassab]

Originally Posted by Jopopsy

I wonder if the generator's position on the coach's frame relative to the heat coming off the engine and the exhaust has something to do w/ the overheating? Meaning, for those with a genset closer to in between both heat sources, I wonder if this still happens?

Based on my look around and observations the answer is no. The exhaust is on the other side of the frame/chassis and the generator's front is ~4' behind and to the outside left of the engine and the front basement storage compartment is between. Plus with the coach motoring down the high... well, I don't see the engine/exhaust being any significant factor, if any.

I think it's more the outside ambient temp and the fact that the Generator's heat is not escaping at the rate it should is the issue.

Mark

[Parrott]

Originally Posted by Jopopsy

I wonder if the generator's position on the coach's frame relative to the heat coming off the engine and the exhaust has something to do w/ the overheating? Meaning, for those with a genset closer to in between both heat sources, I wonder if this still happens?

I know the position on some Thor’s back when I had mine was. Some people under warranty had theirs moved to the last compartment with the vent in the door made especially for the Onan 4000. It has a rubber boot installed between the generator fresh air intake and compartment forcing fresh air to come in from the side instead of underneath.

[craigav]

Originally Posted by Parrott

I know the position on some Thor’s back when I had mine was. Some people under warranty had theirs moved to the last compartment with the vent in the door made especially for the Onan 4000. It has a rubber boot installed between the generator fresh air intake and compartment forcing fresh air to come in from the side instead of underneath.

I haven't had any overheating issues (at least none that I know of or shut down the generator). In any case, does anyone know where to purchase the vents in the pictures above for the onan 4000? ~CA

[Parrott]

Originally Posted by craigav

I haven't had any overheating issues (at least none that I know of or shut down the generator). In any case, does anyone know where to purchase the vents in the pictures above for the onan 4000? ~CA

Check with a Forest River dealer. Have them look under FR3 motorhome. That’s where I got mine.

[Parrott]

Originally Posted by burtdahurt

I am glad I stumbled on this thread. I have been battling with these exact issues with our 2020 34g vision xl. On the highway , the onan will shut off and throw an overheating code. After having an onan tech come out to the rv dealership and not finding anything wrong, I emailed and called jayco, they agreed to install a "vented" genset door. Since it's just getting hot here in phoenix, I will be testing out the fix here this next week. I will update my findings here.



Robb

Is yours the 4000?