# Full Tank/ Empty Tank



## Digger (Dec 18, 2021)

So what is the right thing to do with my new generator with extended fuel tank keep it full? keep it empty? We keep enough gas on hand to fill as needed and rotate through 30 or so gallons a month. With the current fuel prices Leaded gas is close to $6.00 so we're just keeping unleaded gas on hand to run in car and truck and long turn storage doesn't sound good.with no lead? Thanks!


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## motormonkey (Jul 10, 2016)

The shelf life for fuel with ethanol in it is about three to six months. The ethanol absorbs moisture from the air and that will quickly lead to fuel deterioration. If ethanol fuel sits in a tank longer than about six months, it will begin to degrade.
The shelf life for ethanol-free fuel is a bit longer, maybe a year or so, but even it will not last like the fuels from years ago.

Keeping your fuel tank full to minimize air space where condensate could form, storing your fuel in a cool dry place, and using a good fuel stabilizer, will help slow down fuel deterioration, but face it, it is unwise to expect today's motor fuels to last much past a year or so at best. Rotating out your generator fuel into your vehicles on a regular basis is your best bet, but that's a lot of trouble.

That's why I went to propane for my emergency power generator.


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## speedy2019 (Jan 29, 2019)

I have kept fuel in my gen for 3yrs,24/7, and its rarely filled all the way to the top, plus I keep the gen outside in all weather's,.. The only problem I have is the vaporization during the summer months.. I use this in the fuel and start the gen for 20 mins monthly with a low load (without draining the carburettor after) and this seems to work well for me.






Fuel Fit® Fuel Treatment Briggs & Stratton


Briggs & Stratton Fuel Fit® provides up to 3 years of protection against stale fuel.




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## OrlyP (Oct 19, 2021)

I vote to keep it empty and dry then only put gas when needed. Less likely for fuel to cause you any frustration down the road. I treat my generator like it's going into long-term storage. 

Though, I'm still able to carry out the monthly exercise as I've converted it to be able to run also on LP.


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## exmar (Jun 29, 2015)

I've always kept mine full with StaBil and once a year siphon all gas for use in vehicles and replace. Same for a couple of 5 gallon cans and two garden tractors with 5 gallon tanks, everything is in the generator rotation. start generators when I think of it and run for a bit, shutting off gas and running dry. Critical to keeping gas is fuel stabilizer and minimal to NO air space in the fuel port.


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## speedy2019 (Jan 29, 2019)

OrlyP said:


> I vote to keep it empty and dry then only put gas when needed. Less likely for fuel to cause you any frustration down the road. I treat my generator like it's going into long-term storage.
> 
> Though, I'm still able to carry out the monthly exercise as I've converted it to be able to run also on LP.


This might be just me, but I dont think I could be bothered doing the monthly runs if I had to empty it all after, especially if using gasoline.


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## Digger (Dec 18, 2021)

So far I had the New Gen for about 2 months and after breaking in I've only put enough gas in tank to run for 45 minutes or so before running dry every 4 weeks


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## speedy2019 (Jan 29, 2019)

Digger said:


> So far I had the New Gen for about 2 months and after breaking in I've only put enough gas in tank to run for 45 minutes or so before running dry every 4 weeks


I dont think it does the engine much good to starve it of fuel and thats another reason I always keep gasoline in the tank and never let run it dry... Just make sure the engine isn't starved of fuel when you have devices plugged in because the surging from the engine can very easily damage what ever is plugged in to the gen.


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## OrlyP (Oct 19, 2021)

The alternative is to shut off the engine then drain the carb bowl. So between that and turning off the petcock and letting the engine starve, the latter one is easier. I also never heard of small engines getting damaged by starving them of fuel. This is best practice when shutting down the engine.

But I agree, you do so without a load plugged in.



speedy2019 said:


> This might be just me, but I dont think I could be bothered doing the monthly runs if I had to empty it all after, especially if using gasoline.


That's why I use LP. Makes monthly runs easy as turning on the regulator, pressing the prime button, and then start. With no gasoline anywhere in the system, there's virtually nothing to go wrong. If I have to use gasoline, 3 months is probably the longest I'd keep it in the tank before draining it out and store it in a jerry can.


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## speedy2019 (Jan 29, 2019)

OrlyP said:


> The alternative is to shut off the engine then drain the carb bowl. So between that and turning off the petcock and letting the engine starve, the latter one is easier. I also never heard of small engines getting damaged by starving them of fuel. This is best practice when shutting down the engine.
> 
> But I agree, you do so without a load plugged in.


The surging and jumping around cant do the engine much good though, and stresses parts... Its a bit like letting a person run out of oxygen and thrashing around trying to find some.


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## OrlyP (Oct 19, 2021)

speedy2019 said:


> The surging and jumping around cant do the engine much good though, and stresses parts... Its a bit like letting a person run out of oxygen and thrashing around trying to find some.


It won't do any harm either.

I do know that the smaller and later model Honda EU generators have the engine switch reconfigured so that it can be turned off by cutting out the fuel supply.


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## ToolLover (Jan 13, 2020)

OK, so I have a Honda ES 6500 made in 1985.
It has always been drained and run until dry when used on gasoline.
I ran it on non-ethanol gas a couple of times until I converted it to tri fuel.
Honda thoughtfully put a user-friendly drain system on it.
I am sure they had a reason.
I run it on NG occasionally, when I feel like it.
I am aware that some of the newer carbs have plastic in them and that is not ethanol friendly.


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## speedy2019 (Jan 29, 2019)

OrlyP said:


> It won't do any harm either.
> 
> I do know that the smaller and later model Honda EU generators have the engine switch reconfigured so that it can be turned off by cutting out the fuel supply.


Yeah they do,,, I staved mine once out of fuel but didnt like the jumping and surging it did. So I just keep the fuel in the carb and its too much effort for me to get out of my chair to drain the carb manually..


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## OrlyP (Oct 19, 2021)

speedy2019 said:


> Yeah they do,,, I staved mine once out of fuel but didnt like the jumping and surging it did. So I just keep the fuel in the carb and its too much effort for me to get out of my chair to drain the carb manually..


FWIW, let me reassure you that despite what you see the engine is doing when starved of gas, it's not in any way harmful.


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## OrlyP (Oct 19, 2021)

Just to put this out here. As I am working on restoring an old Robin engine, I saw this in the owners manual. This gives credence that stopping the engine through fuel starvation is allowed, if not recommended.


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## tabora (Sep 6, 2018)

I've been shutting off my generators with the fuel valve for the last 35 years after removing the load. Hasn't failed me yet...


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## sdowney717 (12 mo ago)

I vote totally EMPTY of gasoline.
I am installing a 2 way valve to do that, easily drain the tank out. Got a thread started on here about that.
There is no good reason to let gas sit in your generator tank and a lot of bad things can happen and have many times to me over the years.

The gen tank breathes in and out and moisture in the air can get into these tanks as they are vented. Plus the carbs just sitting with little bit of gas left in them , can easily corrode the needle valves can stick, happens all the time.


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## iowagold (Jan 22, 2020)

on plastic tank empty, on metal tank full unless you fog the inside of the tank with engine fogger to hold down rust.
and yes on tank vents as an issue with ethanol fuels!
ethanol empty period...
more damage running ethanol even as drops un used in the carby.

it does nasty stuff on aluminum carby.


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## DaHen (Jan 7, 2022)

I cast my vote for keeping any fuel tank, metal or plastic, empty when storing the equipment away for the season.


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## OrlyP (Oct 19, 2021)

Has anyone considered dropping bags of desiccants in an empty tank? Assuming you find some that could fit in the hole.... maybe string them along so it'll be easy to extract later.


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## JVazquez53 (Jul 8, 2021)

Full tank because I start mine every month, I just keep fuel with stabilizer and never have problems.


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## sledman8002002 (Jan 28, 2021)

I keep them filled (non ethonal fuel, petcock off) along with a dose of StarTron or SeaFoam, regardless of it having a metal or plastic tank.


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## wesr228 (5 mo ago)

If I lived in a place that had frequent power outages, I would keep them full with non ethanol with Sta-Bil or go to propane. Since I'm more set up for storms, I test the generator at the beginning of the season and then run dry. It's cheap insurance to keep it dry and not a big deal to add some fuel when needed.

I do have a couple of the solar generators to keep small loads going in the event of a short outage, up to 3 hours.


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## Browse Deweb (Jan 16, 2021)

My tank has been empty since I converted the generator to run on natural gas. I run my snow blower dry at the end of the winter season. For anyone with a generator that is seldom used, my recommendation would be to store it with an empty tank!


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## BobS (Aug 26, 2020)

All generators are and have been always full. Gas and diesel have stabilizer. All generators are run for a couple of hours under load (gas: 25 to 50% load, diesel: 50 to 90% load) ranging from 1 to 4 times a month. Three of the generators are over 18 years old.


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## Powergen (10 mo ago)

I will have my gen metal gas tank and carburetor empty from gas when I covert to natural gas. What do you guys do to keep the gen metal gas tank from rusting when empty?


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## GenKnot (Dec 20, 2021)

Powergen said:


> What do you guys do to keep the gen metal gas tank from rusting when empty?


I put a little 2-cycle oil in mine. If I need to use gasoline again at a later time, just pour in the gas. The 2-cycle oil won't hurt a thing. I even let a little 2-cycle oil go into the carb after I drain the gas from the bowl.


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## Powergen (10 mo ago)

Great idea GenKnot. How do you spread the 2-cycle oil evenly on the inside surface of the gen tank without removing the tank? Do you just add 2-cycle oil to gas, shaking tank to coat inside surface of gen tank then drain? Thanks


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## GenKnot (Dec 20, 2021)

Powergen said:


> How do you spread the 2-cycle oil evenly on the inside surface of the gen tank without removing the tank? Do you just add 2-cycle oil to gas, shaking tank to coat inside surface of gen tank then drain?


Actually, it is part of a multistep process I use when I prepare my gen for storage after using gasoline. I first drain any leftover fuel in the tank back into a gasoline container. Then I start the gen and run the carb dry. Next, I mix up a heavily dosed mixture (maybe about a cup or so total) of gasoline and 2-cycle oil and pour that into the tank, slosh it around as best I can by tilting the gen, and then open the fuel valve to the carb. I run the gen for a few minutes (it coughs and smokes because of the high 2-cycle oil content) and then I close the fuel valve to allow the gen to use up the fuel in the bowl again. I drain any excess mix in the tank back into my gas container and also drain the carb bowl. Finally, I put a splash or two of 2-cycle oil into the tank, slosh it around as best I can, open the fuel valve to let some of it go into the carb, and close the fuel valve again. That's where I leave it...some oil in the tank and some in the carb. I don't remove the oil on the next run. I just fill the tank with gas and let it rip.

I use the Walmart Super Tech TC-W3 outboard 2-cycle oil for this because it is cheap and because it is blue. I like the blue color because if I see an oil drip under my gen I will know right away if it is engine oil or 2-cycle oil.

I have never really measured how strong I make the gas-oil mixture. I just eyeball it until I think it looks about right. If I had to guess, I would say about 20-25% oil is in the mix. The whole idea of the 2-cycle mix is to coat as much of the carb internals, the cylinder, and inside the muffler with oil as much as possible.

The other thing I do after the final run is to pull the rope until I feel that the piston is nearing TDC on compression stroke to close the valves. This hopefully reduces the amount of moisture entering the cylinder while it is in storage.

My old gen is a 2008 Champion with a metal fuel tank. I have stored it in my shed with an old sheet covering it for years at a time between runs. Our outages are rare, but it has aways started on the first or second pull. I converted it to use NG after the Texas ice storm debacle, so its gasoline days are hopefully over.

My new gen is an inverter WEN GN625i. My plan is to convert it to NG also when the weather gets a little cooler and then I will sell the older gen.


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## Powergen (10 mo ago)

Thats awesome GenKnot. Thanks for the good detail information, I will be using your idea for sure👍. I too will be converting my Champion Inverter 100520 7000w/8750w this fall to natural gas. Next weekend I'm planning on tapping into the output of the natural gas meter with 1in black pipe and fittings reduced down to 3/4 full port valve and 15ft 3/4 natural has hose to America Carb conversion regulator and carb snorkel. Looking forward to do this and thanks for the information GenKnot.


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## OrlyP (Oct 19, 2021)

I am a bit hesitant about adding 2-stroke oil as it might lead to carbon build-up. Though, I know they're meant to be burned with fuel so, maybe I'm worried about nothing. 

Also, caution if you have a more modern generator with a catalytic converter and/or O2 sensors, that stuff may be poison.

I guess something lighter like fogging oil may be more suitable?


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## GenKnot (Dec 20, 2021)

OrlyP said:


> I am a bit hesitant about adding 2-stroke oil as it might lead to carbon build-up.


No worries there since it is only for a brief time that any significant amount of oil is going thru the system.

As for a catalytic converter, that might be a concern if you ran the 2-cycle oil continuously. The TC-W3 outboard 2-cycle oil is ashless and may be cat safe in low amounts but do your research on that as I have never looked into it since I don't have a cat on my gen. Two stroke outboard engines with cats are already in use, but they may have a specially designed cat to handle the 2-cycle oil. I do know that some people put small amounts of TC-W3 2-cycle oil in their cars and make various claims about increased fuel mileage, upper cylinder lubrication, and so forth but take that with a grain of salt. It is much like using Seafoam...some people use it, and some don't with both sides making various claims of good vs evil.


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## sledman8002002 (Jan 28, 2021)

GenKnot said:


> put a little 2-cycle oil in


I agree. It works.


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## GenKnot (Dec 20, 2021)

OrlyP said:


> I guess something lighter like fogging oil may be more suitable?


I forgot to address that...
Fogging oil is sprayed into the carb and its main purpose is to coat the cylinder and rings to protect them during storage. Some people even remove the spark plug and spray it directly into the cylinder also. In that respect, it works as far as I know.

However, the main reason I don't use fogging oil is that it never enters the internal parts of the carb. That is where people often find that they have an issue when bringing a gen out of storage. Leftover gas in the small passages of the carb get gunked up and now the carb needs to be disassembled or even replaced. Even if you run the carb dry and drain the bowl before storage, there will still be gas in those small passages. Try doing this sometime...remove the carb after you think you have cleared it by running it dry and draining the bowl and then see if you can get gas to run out of it. I have done so, and I am amazed at how much gas comes out. Since the introduction of E10 this has become a much bigger issue than with E0.

The 2-cycle oil helps protect the carb's internal passages, seals, etc. during storage. The only realistic way to protect the internal parts of a carb is to introduce something into the fuel. I have been using 2-cycle oil for decades with all my lawn equipment in storage and never had to rebuild or replace a carb due to them getting gunked up. So, in short, I go with what has worked for me. But as always, YMMV.


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## zz28zz (Nov 24, 2021)

I agree using 2-stroke oil works well when storing long term. It coats everything with an oily film that prevents corrosion. It also lubricates o-rings and seals preventing dry rot. I've been using it mixed 50:1 with 100LL av gas (E0) and Sta-Bil to winterize my boats for 30 years with zero issues. I also fog engs after I see exh smoking. The carbs on the boat are from the 90's and still look like new inside.


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## OrlyP (Oct 19, 2021)

What's the longest time have you guys left a coating of 2T oil in the tank and carb? Is there a chance it's going to harden or cake up and be a problem in itself for the carb?

I asked because, as you probably know, propane is my primary fuel. That means, if there's 2T oil residue in the tank, carb bowl and orifices, being exposed to heat while the engine is running through close proximity, might "cook" the oil and turn it into tar.


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## zz28zz (Nov 24, 2021)

8 months is the longest I can remember leaving the boat winterized. I mix it 50:1 so there's not a lot of oil present. Not sure how big a deal the heat would be. Wouldn't think the carb gets all that hot running on propane.


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## Colt Carson (6 mo ago)

I always believed you were better off either never putting gasoline in the system, or keeping gasoline in the system. Of course the gasoline would need to be stabilized and changed periodically. I thought adding gasoline and then draining it was harder on the rubber parts due to exposure to oxygen, and the gasoline residue exposed to air would create a film on the inside of the tank.


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## PLX (Nov 22, 2020)

I've got a 14yr old Coleman Powermate with a Robins Subaru engine. I've always keep the tank full with Seafoam added. I run it every month for 10-15min. Never had any issues with carb or gas. Fires up usually on 1st pull. Super reliable genny. I do the same for my 1974 Ariens 6hp snowblower.


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## Rene (Feb 5, 2021)

Slightly off topic but related. Does running the gen with propane or natural gas after draining/starving the carburetor of gasoline clean out (from jets and bowl) any remaining traces of gasoline from the carburetor? I use NG as my primary but keep 20 gallons of gasoline available during hurricane season as a backup fuel. I will run the gen for 30 minutes on gasoline once a season to verify it will run on gasoline. I always follow up with a 15 to 30 minutes run on NG before completing my maintenance run.


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## GenKnot (Dec 20, 2021)

Rene said:


> Does running the gen with propane or natural gas after draining/starving the carburetor of gasoline clean out (from jets and bowl) any remaining traces of gasoline from the carburetor?


As far as I know the answer is yes. Running propane or NG after gasoline should cause suction thru the carb orifices and clean/dry them out. A little 2-cycle oil mix in carb at that time wouldn't hurt either. The fuel should be evaporated when the NG is run and leave a slight oil residue on the carb innards.


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## iowagold (Jan 22, 2020)

Rene said:


> Slightly off topic but related. Does running the gen with propane or natural gas after draining/starving the carburetor of gasoline clean out (from jets and bowl) any remaining traces of gasoline from the carburetor? I use NG as my primary but keep 20 gallons of gasoline available during hurricane season as a backup fuel. I will run the gen for 30 minutes on gasoline once a season to verify it will run on gasoline. I always follow up with a 15 to 30 minutes run on NG before completing my maintenance run.


it will depend on the gen setup,
every gen is different.

so
how does the gen switch over to the tri fuel.
if it has a sol at the bottom of the carb bowl then the answer is no.
and here is why
the sol shuts off the fuel feed from the bowl so the bowl can have fuel left over if the gasoline tank has fuel in it and the gen was not total ran out of fuel.

the best way is to never fuel with gasoline and stick with the NG or LP only...
and if you need to use gasoline at any time..
do a total flush and dry of the gasoline fuel system.

and yes the crc marine fogger helps on tank rust corrosion bloom on rust as well in the bottom of the fuel bowl.


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## GenKnot (Dec 20, 2021)

iowagold said:


> if it has a sol at the bottom of the carb bowl then the answer is no.
> and here is why
> the sol shuts off the fuel feed from the bowl so the bowl can have fuel left over if the gasoline tank has fuel in it and the gen was not total ran out of fuel.


I don't think that is applicable to Rene's question because he said he is starving the gen while on gasoline to clean out the carb. I think the solenoid would come into play if the gen was shut down or had its fuel source changed while running on gasoline.


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## Rene (Feb 5, 2021)

Thanks for the responses. I did not think about the sol preventing any left over fuel in the bowl from being burned. It also made me take a closer look at the diagrams in the manual and learned a little more bout the gen which is always a good thing.


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## GenKnot (Dec 20, 2021)

Rene said:


> I did not think about the sol preventing any left over fuel in the bowl from being burned. It also made me take a closer look at the diagrams in the manual and learned a little more bout the gen which is always a good thing.


The gasoline fuel solenoid is energized to cut off the fuel in carb. So, if the gen is turned off the solenoid is temporarily energized to stop gasoline fuel flow. This would leave gasoline in the bowl.

Since I am not familiar with operation of the Firman T07571 fuel control module, it would be interesting to know if the module maintains the power to the gasoline fuel solenoid when the gen is being used in the LPG or NG mode. Otherwise, it seems that the gasoline in the bowl would be sucked out. Hmm, I wonder.

This is the gen that recently has had a big discussion about trying to convert to floating neutral and causing issues with the voltage regulator for some people. It seems that the fuel control module may have something to do with that, but since we don't know the design of that module it is hard to say.








How to disconnect neutral from the frame of Firman...


I recently purchased a Firman T07571 Tri-fuel 7500/9400 watt generator from Costco. I also installed a Square D by Schneider Electric QO1DM10030TRBR 30-Amp Generator Main Breaker Outdoor Manual Transfer Switch. I intend to use the generator strictly as a back-up power supply for my home and...




www.powerequipmentforum.com


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