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Old 12-24-2023, 08:10 PM   #1
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Brand: Thor Motor Coach
Model: Axis 24.1
State: Connecticut
Posts: 1,772
THOR #20289
Chassis engine and generator storage

Gasoline powered RV engines need special attention during winter storage
due to the potential for fuel system gum up. Water vapor gets in to the carburetor and reacts with the ethanol in the gas to form a varnish like substance that fouls up the carburetor.

If your chassis engine has electronic fuel injection, ie no carb, it is mostly immune from this problem as the fuel system is generally sealed so water vapor can’t get in. But the ubiquitous Onan 4 or 5.5 kW has a carburetor that will gum up. FWIW the new Onan 2800i generator and someday the 4 and 5.5 generators is/will be fuel injected like all newer chassis engines.

So this is what I do to not gum up over the winter:

After the last camping trip of the season, I fill the gas tank and put in an appropriate amount of Stabil, Sea Foam or similar. Make sure you drive a few miles to mix it up. Then when you get to your winter storage spot, run the generator under load for 20-30 minutes to suck the stabilized gas into the generator’s carb.

Theoretically that is all you have to do until you go camping again in the spring. But I double up and run the generator again once or twice during the winter. I really don’t think you need to run the chassis engine, but I will start mine at least once midwinter and let it run in gear at a fast idle with my foot on the brake until the temp gauge peaks out.

Doing this will potentially save hundreds of dollars of repair costs. But read below how to DIY for about $5.00:

I have done this at least a dozen times with Honda generators, outboards, chainsaws and lawn mower engines.

Remove the carb. On the Onan this is a big PITA. Then remove the float chamber to drain any remaining fuel. Remove any fuel metering screws. Then place the parts in a half gallon can of carb cleaner that you can find at any auto parts store. Shuffle the parts around at least twice over an eight hour period to get any air pockets out and make sure all carb surfaces get contacted with the cleaner.

After eight hours, remove the parts, dry them with paper towels or a shop rag, reassemble, reinstall, close the choke to help pull in fresh gas and start it up.

It has always worked for me.

David

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Old 12-25-2023, 03:28 AM   #2
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Brand: Thor Motor Coach
Model: ACE 30.3
State: Iowa
Posts: 1,208
THOR #28145
Quote:
Originally Posted by DavidEM View Post
Gasoline powered RV engines need special attention during winter storage
due to the potential for fuel system gum up. Water vapor gets in to the carburetor and reacts with the ethanol in the gas to form a varnish like substance that fouls up the carburetor.

If your chassis engine has electronic fuel injection, ie no carb, it is mostly immune from this problem as the fuel system is generally sealed so water vapor can’t get in. But the ubiquitous Onan 4 or 5.5 kW has a carburetor that will gum up. FWIW the new Onan 2800i generator and someday the 4 and 5.5 generators is/will be fuel injected like all newer chassis engines.

So this is what I do to not gum up over the winter:

After the last camping trip of the season, I fill the gas tank and put in an appropriate amount of Stabil, Sea Foam or similar. Make sure you drive a few miles to mix it up. Then when you get to your winter storage spot, run the generator under load for 20-30 minutes to suck the stabilized gas into the generator’s carb.

Theoretically that is all you have to do until you go camping again in the spring. But I double up and run the generator again once or twice during the winter. I really don’t think you need to run the chassis engine, but I will start mine at least once midwinter and let it run in gear at a fast idle with my foot on the brake until the temp gauge peaks out.

Doing this will potentially save hundreds of dollars of repair costs. But read below how to DIY for about $5.00:

I have done this at least a dozen times with Honda generators, outboards, chainsaws and lawn mower engines.

Remove the carb. On the Onan this is a big PITA. Then remove the float chamber to drain any remaining fuel. Remove any fuel metering screws. Then place the parts in a half gallon can of carb cleaner that you can find at any auto parts store. Shuffle the parts around at least twice over an eight hour period to get any air pockets out and make sure all carb surfaces get contacted with the cleaner.

After eight hours, remove the parts, dry them with paper towels or a shop rag, reassemble, reinstall, close the choke to help pull in fresh gas and start it up.

It has always worked for me.

David
Another option is to use only E 0 fuel. In a lot of places that means premium. But here in Iowa there are outlets that do sell E 0 87 regular. That does mean you will have to plan ahead to purge any ethanol from your fuel system by filling only with E 0 fuel for a few fill ups before you plan to put your unit to bed for the winter. Also keep your tank full when you store it to prevent condensation in the fule tank.
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Old 12-25-2023, 05:11 AM   #3
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Brand: Thor Motor Coach
Model: Hurricane 29M
State: Texas
Posts: 2,672
THOR #11781
On my Onan 5500 the carb is real easy to remove, just a couple of nuts hold the filter housing and carb. There is also a drain screw on the carbs bowl. My handbook says to drain the bowl before putting it in storage. This is supposed to prevent gumming of unused fuel during storage.
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Old 12-31-2023, 01:13 AM   #4
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Brand: Still Looking
State: Maryland
Posts: 13
THOR #30935
Hi Manuel says to run Gen two per month . The problem is gas goes bad real quick theses day You can put in Fuel additive in that would help. One note for warranty make sure you do run gen 24 hours per year or they can turn down warranty
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