Propane filter?

[kupchu9702]

I have the Onan generator, on my 2015 Grand Tour, in for a level 2 service at 250 hrs., at Cummins Onan service center, not first time being serviced. They have discovered that the throttle body is gummed up. At first they thought the throttle body was not working so they ordered a new throttle body. So they dropped generator to remove it. Once removed they inspected it they found the body was not inoperable but severely gummed up. They tried cleaning it out but said it was so bad they wanted to replace with a new one. I asked why it was this way and they said it was due to poor fuel and moisture. At first they said it was due to not using it frequently enough and that I should run every month to keep it cleaned out. I did have this issue with a gas generator I had in a previous RV. I am aware of gas and diesel fuel gumming, but have never heard of propane fuel doing this as well.

I do see that in-line filters for propane do exist. Has anyone else had this issue with their unit or has anyone installed a filter just for this issue?

They want $1500 to do this. Not under warranty as it was fuels fault, not malfunction of parts. Am I just being jerked around?

Pretty pissed off as I and between a rock and a hard place with this.

Any help or ideas will be appreciated.

[73shark]

Never checked mine but isn't there any air filter? And not sure how propane vapor could gum up the TB. And assuming it does, not sure why it can't be cleaned. I'm initially voting "jerked around".

[J. Morgan]

Gummed up from fuel in about a year?

I am not going to buy that on first glance.

I have lift trucks that have run for 30 years on propane and never gummed up once....

On the other side of the coin I have had four propane regulators plug up on my Airstream in three years use....


Gradiens super tenui glacie.

[Wolfe]

you need to drop the tank and do a visual internal check, you could have got a load of bad
fuel. (tank cleaning ?)

[OTRA15]

Originally Posted by Wolfe

you need to drop the tank and do a visual internal check, you could have got a load of bad
fuel. (tank cleaning ?)

How does one look inside a propane tank (if I understand this situation correctly)?

[SpletKay06]

The fuel is injected after the throttle body, usually if the throttle body is getting varinshed its from gasses going through the pcv valve. Try using a better oil and putting more load on the generator they are designed to run around 50-70% load. The regulator for the lpg well remove any oil in the lpg so its not fuel related.

[J. Morgan]

I think you are right, the gum is much more likely to have come from PCV.

That being the case, I say it IS a warrantee issue.


Gradiens super tenui glacie.

[73shark]

On a gas engine, the PCV is vented to the bottom of the carb or TB or intake manifold because there's little or no vacuum to suck out the blow-by from the crankcase. Wonder how it works on a LP engine.

[SpletKay06]

Originally Posted by 73shark

On a gas engine, the PCV is vented to the bottom of the carb or TB or intake manifold because there's little or no vacuum to suck out the blow-by from the crankcase. Wonder how it works on a LP engine.

Most newer engines gas included run the pcv in before the throttle body. Its also getting more popular to use a small vacuum pump to assist.

[73shark]

Originally Posted by SpletKay06

Most newer engines gas included run the pcv in before the throttle body. Its also getting more popular to use a small vacuum pump to assist.

Can you point me to some cars or trucks that do that?

[SpletKay06]

Originally Posted by 73shark

Can you point me to some cars or trucks that do that?

3.6 pentistar, 5.7 Hemi's, used in Jeeps and Ram trucks the list goes on. The Chevy Aveo's had the same problem as well with the pcv cruding up the throttle body's

[J. Morgan]

Originally Posted by 73shark

On a gas engine, the PCV is vented to the bottom of the carb or TB or intake manifold because there's little or no vacuum to suck out the blow-by from the crankcase. Wonder how it works on a LP engine.

Every small engine I have ever seen has the PCV draw just behind the air filter.

Now, I in no way claim to have seen a majority of small engine types and brands or even a sizable fraction thereof.


Gradiens super tenui glacie.

[kupchu9702]

I hate to show my ignorance, but what is a pcv valve?

[kupchu9702]

Where do you go to get LPG issues worked on? My dealer is actually a Mercedes dealer with Airstream motor coach as a side line. Won't touch LPG issues. This is why I took it to Cummins dealer. Since I don't have much knowledge regarding this, I feel I am getting taken.

[SpletKay06]

Its unfortunate that the Cummins dealer is incompetent. But the issue has nothing to do with the LPG it is a condition of internal blow-buy and use. Personally I would find a different shop to service your coach. Now as far as the throttle body goes a good cleaning a new air filter and and a pcv valve should fit it.

[73shark]

Originally Posted by kupchu9702

I hate to show my ignorance, but what is a pcv valve?

Positive Crankcase Ventilation- Started back in the 60s where they allowed the intake to suck a partial vacuum on the crankcase (usually thru a valve cover back in the day) to remove and burn blow-by gases. The PCV valve was usually stuck in the valve cover and connected to the intake manifold w/ a hose. There was another pipe or hose that was usually connected to the air cleaner and the crankcase (usually via the other valve cover) to allow filtered air to be drawn into the crankcase. Today's engines are different in that some use an orifice instead of a valve and there's probably other differences that I'm not aware of since my shadetree days on newer vehicles are behing me.