2018 Vista 29VE generator issue

burt6274 · 01-01-2023, 03:13 PM

Hopefully this won't be a duplicate. I had one completed and when I went to post found I had been logged out and appears I lost the message after logging in.

First common issue with 36 error generator runs for varying amount of time. But my issue appears to be a bit different than the ones that I've found in other threads or on Youtube.

So I wanted to see if anyone had experienced the same issue and what the solution might have been.

First all maint is up to date. Oil level is fine. New Onan fuel pump and filter were installed about 6 months ago and that appeared to solve the issue until our November trip.

It appears that this failure is related to the ambient temperature. When it is very cold the generator runs all night with no issues at all. If it is moderately warm is may run 15 to 20 minutes or so and then quit with the 36 error code. Anything from 50 to 60 degrees (or warmer) and the generator starts failing, even though the generator is not reporting an overheating error code.

When it quits holding the stop button on the generator causes a relay click but the fuel pump does NOT run and of course doesn't prime.

After letting things cool off for about 15 minutes it will prime again, but then only runs long enough to use the fuel in the carb bowl. And it won't prime after that until it cools off again.

I'm hoping it is not the new fuel pump, but thinking that it might be the controller.

Has anyone seen this issue and if so what did you find was the solution?

Thanks,
Burt

**creativepart** · 01-01-2023, 03:36 PM

I had a similar problem and know how to fix it. Wait, that's not true, I was joking. Sorry.

We once had a Class C RV with an Onan 4,000w gen and it did the same thing. So, after trying everything you did, we took it to the Cummins/Onan shop to have it fixed.

They ran it in the parking lot every day, all day for 5-days. It never once failed. They were able to use up an entire 1/2 tank of gas. We always said, we know how to fix it... just park at a Cummins/Onan service shop.

I'm embarrassed to admit, we never solved it. We traded that Forest River RV on our Winnebago and have had no problems since.

We always assumed it was some sort of fuel delivery vapor lock.

I have heard of people that add an auxiliary electric fuel pump or trace the fuel line back to the gas tank looking for any sharp bend in the line.

Check out these YouTube Videos on the topic. Maybe one may help:

https://www.youtube.com/results?sear...arts+then+dies

Good luck!

burt6274 · 01-01-2023, 03:50 PM

Thanks, I had thought about vapor lock, but the fact that the fuel pump does NOT run when trying to prime shortly after the failure would seem to not be a vapor lock issue. One thing that I can try is to do the same thing I did when we first got the MH. That was pull the fuel line off where it is clamped to the fuel filter. I then ran a separate fuel line to a small gas can with Seafoam and gas mix and let that run to treat the carb. That test in this case would totally eliminate the fuel line path from the tank to the generator. I don't think that will fix or identify the issue in this case. So I'll have to dig into it a bit more to see if I could be so lucky as to have some kind of intermittent connection that is causing this. Beyond that I may try a new controller before going though the pain of replacing the fuel pump and trying to get it replaced under the part warranty. Not that changing the controller is a picnic either.

dkoldman · 01-01-2023, 07:51 PM

I have 2019 29ve and have not seen. I assume our designs are the same?

We spent 4 days in Houston this past summer and temp outside hit 100+ each day. We were boondocked with no SP and the generator ran about 70% of the time. The AGS was on; it was not in Quiet Time mode. It stopped started based on inside coach temperature. Fridge went to propane with Generator shutoff.

We had no issues, when I got home I cleaned the compartment and soot around engine; added a little oil and that was about it.

I fear these threads, because if I ever see this condition, not sure what I would do because it sounds like a hit and miss type concern. I would ask a mobile tech just to see if they seem verse on the issue, otherwise, I would take it to Onan. They may charge more, but likely to get right to the real problem. Just make sure they are not too busy. Some dealers don't spend the time to access all of the factors and may dismiss what you have already discovered.

burt6274 · 01-02-2023, 10:07 AM

Yes, it is a pain. Especially when it is a bit intermittent.

We have a good RV shop locally that is also a certified Onan repair center. They do tend to be pretty busy but are only 4 miles from the house so that is a plus.

They don't do any chassis work so we have another shop that is also 5 miles away that does work on motorhomes, buses, trucks, etc. That was the shop that replaced the fuel filter and pump last year.

I used an endoscope to look around near the fuel pump. It's still hard to see clearly and I wasn't able to twist the scope around enough to see where the fuel pump plugs in.

But I moved the wires around a bit while looking. Started the generator up and it has been running for over an hour and a half with the ambient temperature around 54 degrees.

I'll let it run for another 30 minutes or so under load and then try it again tomorrow.

If it decides to keep running over the next few days of testing I'll disconnect the batteries and pull the control module out of the way so I can inspect the fuel pump connection.

Not much point taking it to the shop until I can make sure it can be reproduced when they get to work on it.

Fortunately we no longer rely on the generator to run the fridge when we are on the road. Converted from the RV style to Residential style, and that runs fine off the Inverter.

Just need the generator sometimes when we stop for lunch and need the Microwave, of if stopped overnight boondocking and need to run A/C or space heater.

burt6274 · 01-04-2023, 01:55 PM

Well, it is failing more consistently since the temperatures have been running from 50+ up to 70 for the last couple of days.

Definitely when it shuts down with the 3-6 error The fuel pump will not run when holding the stop button down even for long periods of time. The fuel shutoff solenoid does engage you can hear the click when pressing the stop button.

Talked with Onan support and they tend to agree that it sounds like the controller is failing when it reaches a certain temperature. That type of failure has been seen before.

So I'll be removing the controller and checking the wiring as something else to double check. But it seems unlikely to be a wiring issue given the symptoms.

Looks like I'll be ordering an expensive controller to resolve this. While it is expensive (around $500) by the time I pay a tech to try and trouble shoot this that $500+ will be a bargain. If it isn't a connection and it turns out to not be the controller that pretty much leaves the new fuel pump failing but Onan support thinks that is unlikely.

Probably will be a week or two before I get around to this task. Once I either find a wiring issue or replace the controller I'll update with the results.

burt6274 · 04-04-2023, 02:57 PM

Wanted to get back to this thread after finding the issue.

It was ;the brand new Onan OEM Fuel Pump!!!!!!!

We had a trip coming up in March but couldn't find anyone who could get it in and promise that it would be ready before the trip.

So I worked on troubleshooting the root cause. I noticed that when the generator quit it didn't appear that the fuel pump would run if you held the stop switch to prime it. After it had cooled down it would run again. I got some insulation piercing probes and was able to connect to the wires close to the fuel pump. Verified 12V when priming and cold.

Let the generator run until it quit. Verified that I still had 12V when priming but the pump was NOT running.

So the brand new Onan OEM fuel pump had failed in only a few months. Too late to try and get it replaced in warranty.

Next problem was no one could promise to replace the pump before our trip. Second problem everyone appeared to be out of the fuel pumps including Onan online.

I finally found one at the nearby Onan / Cummins shop in Knoxville and ran over and got the pump and a new fuel filter.

Wound up installing it myself and it is a PITA, but doable. If this pump fails again I'm going to move the filter and pump outside of the generator proper, and add a shield around it. That way it will be easier to replace in the future.

After change the pump and filter it has been running just fine even with temps in the 70's - 80's.

Really was bizarre, Onan support didn't think that it would be the new fuel pump when I spoke with them on the phone. But that is what it was..

Hermes2 · 06-06-2023, 01:42 PM

I've had similar issues with our 5500. This may be old news. I've found out that Cummins has a Customer Engineering Bulleting dated April 20, 2017 that identifies a hot air re-circulating problem that can cause the genny to shut down and throw a "36" code.

Generator Set models included: HGJAA, HGJAB, HGJBB, KY

To summarize, they recommend installing a hot air discharge duct that redirects air away from the cool air intake. There are a number of these ducts available depending on where the genny is installed.

Look up document MC-10154771-9999 for details.

One example of a duct is here: https://www.coloradostandby.com/cumm...ight-026-00522

burt6274 · 06-06-2023, 04:26 PM

Thanks, I'll look at that tech bulletin and see if maybe they have some others that would apply.

In my case it was definitely a defective new OEM fuel pump that was failing when the pump heated up. The new OEM pump has continued to work with no issues even when we were in temps in the 80's.

If I can find access to the tech bulletins maybe they have some other useful ones for the 4000 series.