Converting Onan generator from gas to propane

[hedgehopper]

Our Northern Lite 10-2 CD has an Onan propane-fueled generator which has never given us a bit of trouble. I am considering the purchase of a Class A with a gasoline-fueled Onan generator and have heard a lot of horror stories about problems with such generators. So I am wondering if a gasoline-fueled Onan generator can be converted to propane-fueled.

[ford_truck_guy]

For my experience, I have 2 @ 40# LP bottles... When dry camping at the tracks here aremy numbers running my Onan LP 6500

no load - 32 hrs
1/2 load - 20 hrs
full load - 13.5 hrs

Yes - THIRSTY ! ! ! ! !

[johnhicks]

Thanks Doug. I figured it was mainly economics.

[dougrainer]

johnhicks wrote:
If I was running the gen and the furnace in really cold weather I'd be looking at around 24 to 30 hours per 65-gal tank fill. Not real practical. They both seriously drink propane.

Several years ago I added an Extend-A-Stay hookup to run the furnace and lately a small gas generator to provide the power if I run into a Texas freeze situation. I've needed it and didn't have it; now I've assured I won't need it.

The only reason to buy a MH with a propane generator is if you really really like the MH and it's a bargain price.

Maybe someone can answer; why were propane generators a fad for a while rather than gas or diesel? Price?

LP powered Gensets on Class A DIESEL motorhomes were a fad from about 1998 to 2002/3. The reason was simple. The COST of Diesel motorhomes dropped after 1996 or so, due to Monaco and other starting to build motorhomes in the sub 200K range. The most popular were in the 100K to 150K range. RV Diesel Gensets were not that common. So the price was higher. Only on the higher line Diesel pushers. So, to get the price range in that 100K to 150K they installed converted Gas to LP gensets. a LOT cheaper to do that almost half the cost. So, once the market started building thousands of lower cost Diesel pushers the Genset makers(really Onan) upped production and with more volume the price came down. Also, OEM's started hearing from dealers and RV'ers about how upset they were on the time limitation of LP gensets. Back 23 years ago, we had brand new Monaco Diplomats have the LP gensets fail at delivery in hot weather. The Genset LP regulators gummed up and failed. After having about 4 of those happen one summer the Owner decided to NEVER order another Diesel Motorhome with an LP genset. We ordered and optioned the higher priced Diesel Genset. Doug

[Skibane]

johnhicks wrote:
why were propane generators a fad for a while rather than gas or diesel? Price?

They're cheaper, lighter and more compact than diesel gensets.

Motorhomes with diesel engines don't have a gasoline tank - but they do have a propane tank.

Ditto for travel trailers and fifth-wheels.

[johnhicks]

If I was running the gen and the furnace in really cold weather I'd be looking at around 24 to 30 hours per 65-gal tank fill. Not real practical. They both seriously drink propane.

Several years ago I added an Extend-A-Stay hookup to run the furnace and lately a small gas generator to provide the power if I run into a Texas freeze situation. I've needed it and didn't have it; now I've assured I won't need it.

The only reason to buy a MH with a propane generator is if you really really like the MH and it's a bargain price.

Maybe someone can answer; why were propane generators a fad for a while rather than gas or diesel? Price?

[JaxDad]

hedgehopper wrote:
I am considering the purchase of a Class A with a gasoline-fueled Onan generator and have heard a lot of horror stories about problems with such generators.

A good friend who travels with me quite often has a DP with a propane genset.

The heartaches of trying to find LPG, constantly, is a BIG issue. In cold weather he’s burning propane for heat AND the electricity to keep the heat running.

I don’t know how big his tank is, but in ‘heating season’ he’s refilling his LPG every other day.

[Skibane]

Cummins12V98 wrote:
The key to any gasoline gen is using non ethanol gas. Or proper fuel stabilizer.

Most motorhome generators are plumbed into the chassis fuel tank(s) - which means that you would also have run the motorhome engine on non-ethanol gas. Every time you fueled the motorhome up, you would be paying a lot more.

One of the best strategies for running ethanol gasoline in generators is to shut off the gasoline supply (i.e., install a fuel cutoff valve if none is already present) immediately prior to long-term storage, and then run the engine until it has consumed all the remaining fuel in its carb bowl.

If the generator engine has an electric fuel pump, you can install a "winterize" switch to manually shut it off while the engine is running, thereby accomplishing the same thing as installing a fuel cutoff valve.

Naturally, you don't want any AC electrical loads connected to the generator while doing this, because the engine will stumble and surge as it runs out of fuel.

Some engines have a fuel drain screw on the bottom of their carb bowl. Temporarily opening this screw drains all the gas out of the carb.

Basically, the idea is to avoid storing the generator for long periods with any gasoline still in the carburetor. The ethanol in the gas attracts water (which corrodes delicate parts in the carb), and the more volatile components in the gas gradually evaporate, leaving varnish behind.

[Cummins12V98]

The key to any gasoline gen is using non ethanol gas. Or proper fuel stabilizer.

I would love to change my CUMMINS Commercial LP 6500 gen to gas. It’s VERY THIRSTY.

[fj12ryder]

FWIW, we had a built-in Onan 5500 in our last toyhauler. We owned the trailer for 10 years, and had about 60 hours on the generator. I ran it rarely, but always drained the carb when I was done with it. It was never run regularly, but also never failed to start when needed. If you don't drain the carb and only run the generator irregularly, you'll very likely have issues. There was never any fuel in my Onan's generator when it was sitting idle. Not a good practice, to not use it regularly, but it worked for me. Maybe just good luck.

[Grit_dog]

hedgehopper wrote:
I am considering the purchase of a Class A with a gasoline-fueled Onan generator and have heard a lot of horror stories about problems with such generators.

Here's a funny story to counter your internet wisdom about the horror stories of gas powered Onans.

Camper in sig, bought last year. Orig owner literally used it like once or twice the first year and it sat since 2017/2018 unused.
Had it advertised as a propane generator.

As I really didn't want LP gen and also didn't believe him, I asked multiple times. (Camper is 300 mi away at this point, can't just run over and check it out) Answer was the same. "I've started the generator several times, and have to turn on the LP, light the stove and only then will the generator start!"
(Some of you will be really laughing by now...)
Regardless, I head out to inspect and buy it.
He goes through the whole deal lighting the stove to fire up the genny.
Turns out he had NEVER added gas to the gas tank. There was apparently just enough gas still left to run the generator (from the selling dealer when new??) as it read empty and the fuel station pump only pumped air.

Bottom line, that generator actually fired up and ran somewhat acceptably on what had to be 4 year old gasoline!
Not recommended, but....it runs much better on gasoline purchased in this decade!

[dougrainer]

A Gasoline powered Onan is exactly the same as a LP powered. The ONLY difference is fuel to run it Gasoline or LP. You read about problems with Gas powered Gensets because they are probably 95% of all RV Gensets. The ONLY problem with Gasoline Powered Gensets is the USERS fault, not a design problem. Gasoline Gensets need to be run at least 1 hour a month. This keeps the fuel from deteriorating and gumming up the Carb fuel jets. Same is true for Home lawn equipment. Don't properly treat and store your Gas powered Home appliances, you will have a ruined appliance. Having a LP powered Motorhome in a Gasoline and Diesel powered Motorhome LOWERS its resale value. LP powered gensets are limited by the size of the ASME LP tank on the motorhome. Usually the LP tank has no more than 25 to 27 liquid gallon capacity. LP powered Gensets consume 1.1 gallons LP at full load and about .7 gallons at 1/2 load. So this gives you at best 20 to 24 hours before LP tank refill. Even less if you are using onboard LP appliances. Gasoline Powered gives you 80% of the Gasoline tank capacity at .9 gallon 100% load and .6 at 50% load. You could go 3 to 5 days 24 hours a day. AND, LP gensets are also prone to problems from gummed up LP regulators. Especially when it is hot outside. Doug

[wildtoad]

Do you think the number of “horror stories” significantly out number the instances of people who have had zero issues? Of those with issues, how many have to do with fuel source versus issues due to no or poor maintenance?

It will make you sleep better than swap.

[johnhicks]

To make it feasible on a class A you'll also need to install a much larger propane tank. Mine is 65 gallons and is expected to provide about 50 hours runtime. I've never tried it that long.

I believe such horror stories involve portable generators and installed generators that rarely run. Proper regular exercise of a generator should prevent carb gumming.

Also getting motorhome non-removeable propane tanks filled can be a major pain..

[fj12ryder]

There are kits to adapt an Onan to run on propane. Last time I looked they weren't all that expensive even. And didn't look all that difficult to install, but on a motorhome, access could be an issue.