Onan LP gen help

bigfelipe · 06-21-2018, 04:52 PM

So I ran out of propane running the generator a couple days ago. It seems the gauge doesn't work... Separate issue. I'm new to this RV and onboard propane in general. I didn't know about bleeder valves and apparently neither did the guy who filled it... Here's where I am with it...

Ran out...

Refilled the tank(9.5 gallons in an 11gallon tank on a hot day). Slightly over filled...

Genset would start right up but not stay running. All other gas appliances working fine.

Not knowing about the fill level I looked at other issues.

Oil was low. Thought it was a low cut out so I topped off. No help.

Back to propane, I found out about the valve and opened it. Bled off a bit of liquid and then it went to gas.

Closed the system to let any pressure check valve reset.

Still nothing. Loping at idle and dies within about a minute.

I had noticed that the little breather tube filter was rotten while I was under there and made a mental note to order a new one.

Then I had a thought that maybe it was plugged somehow. I got it running long enough to run around and crawl under and put my finger over it to see if there was vacuum...

It instantly idled up, evened out, and run fine... I removed my finger and back to loping. Did this several times to confirm.

Held a chunk of the non-rotten foam over the hole and it didn't restrict the flow enough to stay running. I eyeballed the size of the tube and grabbed a pen cap out of the RV and stuck it in the tube. Put a piece of the filter in it(has three small holes in the end of the cap) and it's running like a champ. Ran it under load and without. No problem...

Or is it..?

My understanding is that the tube is a breather and should be open. Why does it need to be sealed for my gen to run? Anyone able to shed some light on the subject? I'm on the road now so my ability to test things is limited.

bigfelipe · 06-21-2018, 05:07 PM

Oh yeah... It's an Onan Microlite 2500LP in a 2007 Roadtrek SS Agile with an 11gallon propane tank if any of that is pertinent...

BBQ · 06-21-2018, 08:20 PM

Quote:

Originally Posted by bigfelipe

...

My understanding is that the tube is a breather and should be open. Why does it need to be sealed for my gen to run? Anyone able to shed some light on the subject? I'm on the road now so my ability to test things is limited.

I am not sure which tube you are referring to.

Do you have a photo?
get a selfie stick and grab a pix.

On the gasoline Onan, the tube is the static port for the carburetor.

bigfelipe · 06-21-2018, 09:42 PM

I do have a photo but don't have a way to host it and the forum doesn't allow uploading pics only links as far as I can tell.

The tube is the one routed under the front side of the generator that has the foam filter on the end everyone always mentions breaking down and needing replacement. I honestly don't know what it is called.

bigfelipe · 06-21-2018, 09:47 PM

The part is called an Onan Vent Hose Filter... Don't know what it vents...

avanti · 06-21-2018, 10:09 PM

Quote:

Originally Posted by bigfelipe

I do have a photo but don't have a way to host it and the forum doesn't allow uploading pics only links as far as I can tell.

If you go to the reply window (not "quick reply"), you will see a bunch of buttons on the top. Click on the paper clip button and it will take you to an upload tool.

GBUSMCR · 06-21-2018, 10:58 PM

Another item to check might be the regulator. I had the same problems you described and replacing the regulator solved the issue. FWIW

<<B-Guy>> · 06-21-2018, 11:42 PM

Quote:

Originally Posted by bigfelipe

I do have a photo but don't have a way to host it and the forum doesn't allow uploading pics only links as far as I can tell.

The tube is the one routed under the front side of the generator that has the foam filter on the end everyone always mentions breaking down and needing replacement. I honestly don't know what it is called.

Crankcase maybe? - just a wild guess, no experience with Onan's

Brian

bigfelipe · 06-22-2018, 03:00 AM

Here's a pic after I stuck the pen cap in it...

BBQ · 06-22-2018, 03:33 AM

Quote:

Originally Posted by bigfelipe

Here's a pic after I stuck the pen cap in it...

That's the regulator vent tube. It is supposed to allow air to flow freely into the static side of the regulator.

It appears the demand regulator is not working.

BBQ · 06-22-2018, 03:37 AM

.

What is your altitude?

[Edit] mmm... I am only asking; I don't know if that makes a difference.

buzzard28 · 06-27-2018, 07:14 PM

That is called the regulator hose. It has to blow and suck depending on what the generator wants. It should have a filter on the end to keep bugs from going in and blocking it. The new ones have a foam filter which sucks up water on rain days and are no good. Folks are putting fine screen mesh and having great success. Others are putting small fuel filters. As long as it can suck and blow unrestricted.When your generator acts weird this is the first thing to check.

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