2017 Airstream Interstate Onan Generator won't start

[Frankelcid88]

Hello,

I was out in the middle of nowhere and wanted to charge my batteries. I only have 13 hours on my Onan 2.5HGJJ generator. I flipped on the propane and pressed the start button. Its cranked and would not start...not even a pop or two. I then prayed for my solar to save us : (. I am pretty handy and good with engines. This one has me stumped. I want to exhaust all possibilities before I bring it to the Stealership or the Onan people.

When I arrived home from my trip, I checked the following;

1) Propane flow - Stove works and external LPG fitting has flow.
2) On/Off Solenoid make the familiar hollow clicking when switched.
3) No flashing error codes on the switch inside the van.
4) Switch LCD did flash 8111.5 during cranking. There is a cryptic Onan reference to low batteries for this. Batteries are fully charged and even tried with van motor started.
5) Smelled propane after a long crank. 30 second crank as recommended by Onan to generate an error code.

Went underneath the van to the generator and did these checks;

6) All battery connections are nice & tight
7) Onan air filter is pristine
8) Vent tube had a foam boot on it. I removed it and sent a wire up the tube. No blockage.
9) The unit switch on the generator was flashing! Error code 36. Onan say this error can be caused by virtually anything.
9b) Stuck my finger down below the unit switch to the hidden breaker switch below it. (WTF design?) Breaker switch was in up position....It switched easily...maybe too easily to the down position. I pulled it back up. Hmmm.

Other info;
10) I still need to think small and pull the sparkplug and check it's connection. It's really tight in there. Will do that today.
11) The only change since it ran last...I had the propane filled. Could this have caused damage if done improperly? Regulator?

I know there are experts out there and I appreciate any insight before I bring it to a shop where they start throwing parts at it.

Thanks,
Frank

[Lily&Me]

I have an older unit than yours, but have consistently found on both of mine that the generator starts more predictably when I turn the vehicle engine on first.

Just seems to like that power boost.

Maggie

[uncle_bob]

Hi

Best guess would be no spark based on what you have looked at so far and tried.

Bob

[Titus]

I have got in the habit of firing up the stove first if its been a long time since I have run the generator. This reduces the generator crank time significantly. I guess that doing this helps gets the lines filled with propane. Though not real clear why this helps since the propane line to the stove splits off from the generator propane line quite a ways back. But your repeated cranking should have accomplished the same thing. Most places will not fill the propane without having the tank valve (solenoid for us) closed. Filling it with the valve open could (would?) hurt the regulator. Not sure how/if a regulator could be damaged such that the generator wouldn't work but the stove does. Maybe the generator is more sensitive to inlet pressure? It certainly needs more propane flow.

I have never seen a need to start the engine before starting the generator - but maybe our house batteries have a better SOC than those of Maggie's Interstate.

Where did you find the hidden breaker? Not sure what you mean by 'unit switch'?
Seems like you might be saying that it is behind/below the inside start switch. I was aware of one inside the generator access panel where you check/add oil, but you seem to be describing a different (another?) one.

[uncle_bob]

Hi

When they fill the propane tank, they are filling it with liquid propane. The regulator is not really set up to be flooded by liquid. Folks have reported issues ....

Assuming the stove lights and stays lit for a while, your propane system is working.

Bob

[ArcherTC]

Simple item but I don't think you mentioned checking the oil level?

[kaylorsan]

Originally Posted by ArcherTC

Simple item but I don't think you mentioned checking the oil level?

I'm going to go with ArcherTC. My guess is that your oil level is low. That, or the breaker was off. I've had both of these issues in the past.

[Frankelcid88]

I spent the afternoon doing some research and trying some additional steps. Still no success;

- Rechecked the oil level very clean and very full. Van is on very slight incline.
- Spark plug wire is attached
- Did the redneck "spray starter fluid" on the air filter....still did not fire
- Ran a wire up the vent tube again. No resistance.
- Tested propane flow by Turing on water heater and gas stove. No problems.
- I checked the breaker on the actual generator under the van (see pic). It is in the "on" position
- I could get the start switch on the generator to flash an error code of 36.
I did find the Gen Set switch inside the van will not display Onan error codes

I am going to narrow down my guesses to one of two items:
1st - Bad regulator perhaps busted by the recent LPG fill I had. I read other posts where the LPG flow is impeded by a faulty regulator enough to prevent the Onan from starting

2nd - Something causing no spark. Pulling the plug is too big a job to do without a lift and removal of the spare. I just don't fit under there.

Unless the experts out there know something else...it may be time for either the Onan or general RV repair people.

Including Pictures of (A) start switch on Onan which shows error code (B) Hidden breaker below switch (C) Inside van start switch which doesn't show error code

[StogieMan]

Frank, check the positive and ground wires in the back of the generator. Where they're located are prone to get corroded and brake off or an easy spot to get pulled on accidentally.

[Titus]

Is the problem that the generator cranks but won't start, or that it won't even crank (starter won't engage and engine won't turn over)? If it is the former then cables to the generator are probably not an issue (unless you hear it turning over very slowly).

I believe that you could connect a water manometer where the propane line connects to the generator and monitor it during cranking. Specs on mine call for 9-13" water.

[Tonypaulr]

I just had this happen to me . It would crank but won't start .Before it stopped turning over it was running rough. checked batteries and turned engine on and still same thing .Checked oil and that was not the problem .Finally changed the spark plug and it fired up on the first try and running quieter and smoother then I can remember .

[Frankelcid88]

Thanks for all the advice. Today I lowered the spare and changed the spark plug. Still doesn’t start. Grrrr. The Cummins people are some sadistic designers. Trying to just pull tand replace he plug is pure hell on this unit.

I give up.

Monday it goes the the professionals. I will offer up my credit card as sacrifice. I am betting the regulator is shot. I looked at where Airstream placed the regulator. It’s behind the coiled poop hose on the drivers side. The tank and solenoid are pretty accessible, but then the hose out of the solenoid goes into a cavity with foil tape over the opening. Legend has it the regulator lives in there. I hope the repair shop knows how to conjure the regulator out of its cave without disassembling the entire underbody. There appears to be no shutoff. A mistake here could be spectacular.

I’m going to spend the rest of my day calming down by changing the master cylinder on my 60 MGA.

I will report back what my credit card finds as the solution.

Thanks again.

[Titus]

Please do respond with the result. We have many posts where the solution is never revealed. Good luck to you and your credit card.

[C.Martin]

Following…

We have the same problem. Going to change the oil, air filter, spark plug, and make sure the choke is free and moving properly. I can get it to start after lots of attempts…but we need it to fire up within 5 seconds if it is to be reliable with the ME-AGS-N.

It will be a while before I can get back to work on it again.

[eubank]

I had the same symptoms on my 2016 Onan in the AI. Took forever to get it to just the right people, but here's the short version:

1. The generator is fed by propane that leads first through the Interstate's regulator and then through an internal regulator on the Onan. The regulator wasn't working properly.

2. The rubber hoses feeding the generator were getting old and cracked, so leaky. Replaced them, too.

One of the findings that lead to the conclusion in (1) was that the generator WOULD start if you just partially block the flow of air into the carburator, which, in turn, increases the vaccuum into the Onan regulator.

Like I said at the beginning, it took a bit of doing to locate the right shop to get it worked on. ANd they were nice. As instructed, I took in the AI on a Monday; they removed the generator from the AI so that they could work on it on a bench and gave the AI back to me for interim use. Later in the week, they called to say that the generator was repaired, so I brought the AI to them a day or two later, and they reinstalled it under the rig.

Frankly, I really dislike that generator. It's the noisiest thing in the world. Onan's new version of the same generator is presumably much quieter, but they do not sell a retrofit kit to deal with somewhat older ones.

Good luck with it!
Lynn

[One Smith]

Coming from an old “gas man”—-Spiders love those tiny cavities in the burner assembly. You need to disassemble and check and clean as necessary to clear them out. Generators need 2 things, fuel and fire. If it has both it should run.
Also, disconnect the line between the service regulator and the mixing tube, checking to see if gas is present downstream of the regulator. The strong smell of propane will be there and a little goes a long way.

[One Smith]

How long has it been since you ran the generator? Those spiders will set up shop in as little as 2 weeks. It’s happened to our motorhome generator years ago. Learned our lesson and make a point of firing up the generator at least every 2 weeks. Good luck.

[Frankelcid88]

Had the van to a nice local RV service center in last week. They tested the regulator for the Van LPG and the regulator inside the generator. Both checked out ok. They couldn't spot anything wrong. They next recommended a nearby shop who repairs these Onans. The shop asked if the RV people could remove the Onan to allow them to better address the no-start condition. Here is a picture of the little Onan bastard on its way to be fixed. Hopefully have some new info in the next day or so.

[jmahone]

This may not be the issue you are facing, but I thought it would be useful to this thread for future issues. Apparently, there is a TSB on the regulator inlet/outlet hoses (pre-2017) because they are subject to cracking, which allows air to mix with the fuel, producing a leaner mixture that causes tough starts and/or rough running. I found this out when I was having a 2016 AI Lounge inspected, and they found the genset was running really rough and loud. The fix is to use the newer hoses, which are not (as) susceptible to cracking.

[Frankelcid88]

BINGO!!! - Just heard the repair shop found two hoses inside the generator with cracks. They said the hoses are corrugated (ribbed). They now have a inquiry into Cummins to see if they can use regular LPG hose to replace the originals. It's a little tight in there and they were worried about kinking regular LPG hose. Apparently, OEM parts are hard to find. They found nothing else wrong with the generator. It makes sense now as the first RV shop thought I had a leak.

Hopefully this is the problem and I'll get the unit back into the van soon with a nice bill to pay.

Thank you everyone for your insights. Unless you have a lift, this job is not DIY.