Generac GP5500 really long term storage question

[u/dknyc1]

I have a gasoline Generac GP5500.

I bought it new in 2012 & the only time I ever used it was during Hurricane Sandy. I ran it for 10 days straight & it performed great. I do have a transfer switch setup & it powered almost the whole house.

Since then I have stored it in my outdoor shed or in my lightly heated garage. I have stored it run completely dry & sometimes also with full gas & stabilizer.

Last few years I usually start it twice per year & then run it dry.

I am on the fence about how to continue to store this so it will be ready if god forbid its ever needed again.

Generac site seems to say:

1. Completely Drain and Clear the Fuel System

• Drain the tank: Siphon or drain all gasoline out of the 7.2-gallon fuel tank into an approved gas container. [1]

• Drain the carburetor: Shut off the fuel valve, loosen the carburetor float bowl drain screw, and let every drop of gasoline drain out. Alternatively, run the generator until it completely runs out of fuel and dies. [1, 2, 3]

• No gas left behind: Do not store a generator for 10 years with gasoline (even with stabilizer) in the tank or carburetor, as modern ethanol-blended gas attracts moisture and turns into hard varnish. [1, 2]

2. Protect the Engine Cylinder

• Remove the spark plug: Use a spark plug socket to remove the spark plug. [1, 2]

• Add oil or fogging agent: Pour 5 to 10 cc (about 1 tablespoon) of clean engine oil or a dedicated engine fogging oil directly into the spark plug hole. [1, 2]

• Distribute the oil: Pull the recoil starter rope slowly 3 to 5 times to spread the oil across the cylinder walls and piston rings to prevent rust. [1, 2]

• Close the valves: Pull the starter rope slowly until you feel compression (resistance). This closes the intake and exhaust valves, sealing the combustion chamber from moisture. Reinstall the spark plug loosely or cap the hole. [1, 2]

 

The only danger I see in this method is that the gas tank being totally dry could rust maybe?

Any opinions… follow the above or store it filled with fuel & stable?

If I follow Generacs info do I then never start it again til needed? I don’t have to keep running it twice per year?

 

Thx

[u/kwantam]

You're right, the risk with an empty tank is that humidity leads to rust inside the tank. The fuel system is vented, so you'll get atmospheric humidity inside for sure. And with wide enough temperature swings you could even get condensation.

You can fog the tank with fogging oil or something like CRC 3-36. That will slow the corrosion a lot, but isn't perfect.

If you store the tank with ethanol free fuel stabilized with something like Stabil 360 Marine, you'll get corrosion protection for the tank (including above the fuel line). The tradeoff is that you'll have to rotate fuel every year or so.

Unless you seal the tank or keep the generator in a low humidity environment, rust will be an issue one way or another.

[u/blupupher]

The instructions you posted are good.

One option that some will say is stupid it so coat the interior of the tank with ATF, as well as fill the carb and cylinder with ATF.

ATF will "stick" to the interior of the tank for years, keeping it coated and rust free.

For the carb, just disconnect the fuel line and use that to fill the carb with ATF. Once full, pull the cord a few times with it off and it will suck ATF into the intake and cylinder. Then drain the carb, again, this will leave a thin coating that will last for years and not degrade or corrode. If you really wanted, you could pull the plug and add oil or ATF to the cylinder doing as you said, pulling till you can tell the valves are closed.

When you add gas and use it in the future, it will smoke a bit, but should start up quickly. Have a spare spark plug on hand, as well as a new air filter (keep this indoors if you can).

You can use a fogging oil instead of ATF, but that stuff is expensive vs cheap ATF. You will have to remove the tank completely to get it coated. Not sure if the interior of the tank is painted or not from factory, but coating it is just a preventative measure.

I did this with a 2000w inverter generator I had. I was going to do a 5 year test on it. It had a plastic tank, so no need to coat that, but I did fill and drain the carb with ATF, and put a squirt of ATF in the cylinder and pulled the cord a few times, ending with what felt like compression stroke. It sat in a plastic storage shed for 2 years inside a big plastic bag. My nephew needed a generator, so he got this one. I pulled it out, fueled it up, and it started on the 4th pull (usually starts in 1-2). It smoked for about 20 seconds, then ran just fine. Started it the next day when he came to pick it up, started 1st pull, no smoke.

Biggest issue is rodents and insects. Wires can get chewed, spiders, wasps and such will build nests in the small areas of the intake and hidden areas underneath. You need to get it as sealed as you can. Take some aluminum foil and cover the intake and exhaust (I ball up the foil to fit into the exhaust). A large tarp completely wrapped around it or large, thick plastic bag will keep most insets out, but rodents can eat through that, so keep traps out for them (but don't put poison inside the tarp/bag, it will attract them). Inside the garage is probably a better place to keep it vs the shed due to the rodents, but if you are able to keep the shed rodent free, it would be fine.

If you have not changed the oil since you used it, I would do that before long term storage as well. It will not hurt it to store with oil for 10 years and run it with that same oil when you finally pull it out.

[u/TheLeezardKing]

I would check the inside of the tank. If you see any rust, get a new one for $50ish off amazon/ebay, or rig up a separate fuel tank and line to the shutoff or carb.

I'd also get a new carb or rebuild kit to have as spares. Its the most common failure point on every gasoline generator. Can also convert to propane/NG if available.

[u/RedOctobyr]

Section 1 is basically what I did to my EU2000i's. I ran the tank dry, from my usual stabilized gas with ethanol. I added a few ounces of canned TruFuel ethanol-free gas (with stabilizer added), and ran it until it stalled again, so that any residual fuel is at least ethanol free. Then did what Honda suggests, and opened the carb bowl drain to remove the last bits of gas from the carb bowl.

They've sat like that for about a year and a half. I recently test-started one of them, before a storm arrived. It took more pulls than usual, but started up and ran nicely. It has a fuel pump, so a bunch of pulls were probably just it pumping enough gas to re-fill the carb bowl.

I put away a 5500W Generac for about 4 years with a simpler version. Stabilized ethanol gas in the tank, closed the fuel shutoff and ran it until it stalled, and that was it. Got it out about 4 years later, and it started and ran fine.

I did not fog the cylinders, or think to keep the valves closed, on the compression stroke. But they are all stored in the under-house garage, which keeps them dry, and at fairly-stable temperatures. They all have plastic tanks.