Home > All Products > Generators > Portable Generators > GP Series > GP3500iO
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Model #7128

Starting At

$839.00 MSRP
Where To Buy


The Power to
Live. Work. Play.

Portable generators are a welcome addition to many activities at home, at work, and away. In an emergency, portable generators can provide critical backup power. They make camping and tailgating more comfortable. And contractors appreciate the flexibility portable power brings to the jobsite.

GP Series Accessories

Maximize your investment and maintain your Generac portable generator with a variety of accessories.

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Rated 4 out of 5 by from Good product without much support or info First off I won this in a raffle, so there is nothing to complain about. However I would like to point out a few things that I feel could be done better by Generac. First off, there are no break in instructions included with the generator. I assume every small engine needs a break in period so I had to look this up myself and perform it. Secondly, why no wheel kit? Yes it’s kinda light but would a wheel kit be hard to make or sell? Sure would be handy, so I’ll have to make one myself. Third, it was quite difficult to find where to register the warranty. You really have to search to find it.
Date published: 2021-10-03
Rated 5 out of 5 by from This generator saved our business after the July 28 storm knocked out power in Ripon, WI We are the owners of J&G's Place 2B, a bed and breakfast in Ripon, WI. A massive storm hit Ripon and surrounding areas on July 28, 2021 and shortly after midnight we lost power during the middle of EAA Airventure, when Oshkosh hosts the world's largest airshow for a week. This is also the busiest week of the year for our business. A requirement for a bed & breakfast license is that you MUST HAVE HOT WATER, otherwise you are to close immediately. We were looking at a couple of thousand of dollars of lost revenue if we could not stay open. I got out our Generac 3500IO for the first time, a bit worried about making it work. It took all of ten minutes to set up (put in oil and gas and run our extension cords) and it was easy to use (started on the first pull) and kept our business humming and our guests happy for the two days it took the electrical crews to restore service. It already comes with the oil you need for the oil reservoir. Took about half of the included bottle to get it to the right level. It was nice not having to hunt down a bottle of oil. Ran all night and more on one tank of gas, so it is efficient. Especially impressed with how quietly it runs. One thing I would love to see: is there a wheel & handle kit available for this model, and a rain canopy/cover I could buy so it is easier to transport and also be able to use it in the rain? Thank you, Generac, for saving our business. Best, -Jason & Giselle PS: Using two extension cords plugged into the two outlets on the generator, we ran two refrigerators, a chest freezer, a natural gas hot water heater, two lamps, and 2 CPAP units, and had some Watts to spare, plus we charged phones and tablets through the 2 USB ports on the back of the generator. We buy the most energy efficient appliances available, which means we were able to get by with a much smaller and less expensive portable generator that will fit in the back seat of a Toyota Corolla when it is boxed up, which perfectly describes the 3500IO. We recommend it highly!
Date published: 2021-07-31
Rated 5 out of 5 by from I have tried another of small generators and I should of gotten this year's ago This is a very economical generator good power with excellent fuel usage. I uses for portable power when I am traveling for work. This is one of the quietest generators I have ever had and used in the portable line. I definitely recommend this generator if anybody is looking for a small compact generator that is very easy to move and very portable. This is a replacement generator for a much more expensive generator that if I'd known this generator was as good I would have bought this generator and not had spent the $2,000 on the other generator that I am still fighting for under warranty
Date published: 2021-06-01
Rated 5 out of 5 by from performance operates as all reviews said it would. Love that it is so quiet and starts so easy.
Date published: 2021-03-23
Rated 4 out of 5 by from Louder than expected Heat shield over the muffler rubs against the muffler and is loud and annoying. I'll probably take it off and see if I can bend it away so the metals don't touch each other. I bought the generator to camp with so I want to make it a little more quiet. Haven't gone yet. Just filled the oil and put gas in it to test. Ran a heater and skill saw with no issues.
Date published: 2021-03-12
Rated 3 out of 5 by from Good generator but.. This is a good little generator, but the only thing I have a problem with is that there is no fuel cut off valve. The off/run/choke switch just turns the generator off and does not run the generator out of fuel. I’m thinking as far as storage. I know the manual talks about fuel stabilizer, but I think a fuel cut off valve would be great. I have owned a few generators in the past and all had a fuel cut off valve to run the generator out of fuel when not in use. I have never had an issue with my other generators, but this is a concern for me.
Date published: 2021-02-27
Rated 5 out of 5 by from Quiet and smooth Like so many others, we are experiencing fairly frequent outages. Most are quite brief but recently we had one that lasted all day. If it hadn’t been warmer weather we might have had a problem. So.,.. we took the plunge and bought a generator. Since we live on a townhouse and don’t own it, I decided to buy something with enough capacity for the essentials. I also wanted to be able to run as cord to the neighbours to keep them in heat as weIl. It also had to be quiet and reliable. Portability was important. I found everything I wanted in this model. I’m presently making a storage box to keep it outside do I don’t have to carry it up from the basement although it’s doable. I would recommend this product. As a matter of fact, I recommended Generac to my mother and sister in law. They got a larger one since they had the space and wanted something to run more things in the house. Noise level also wasn’t as big a factor for them.
Date published: 2021-02-18
Rated 5 out of 5 by from Primarily Backup We grew tired of our what seemed like twice monthly power outages-can anyone say aging infrastructure. I researched several generators and one constant was a brand name with a good reliability rating and one that was not out of reach of our pocket book. I picked a Generac non wheeled generator that is semi portable to me(75 lbs is semi for me).It will sit on a cart in our outdoor shed-where I can run it with the doors open. I installed a Reliant Generator through the wall outlet kit that allows running the generator while all our windows and doors can stay shut(hidden Cords). 3 pulls of the recoil is all it took for initial starting out of the box-and ran very steady. Now we can run a portable heat/AC unit if needed along with our other refrigeration and freezer. I need something that was large enough to run a couple of appliances at the same time and this generator was of sufficient amperage and voltage. We are very happy with our choice and after testing out it kept up quite well. Quiet and sufficient power for our needs. We're happy.
Date published: 2021-02-02
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GP3500iO - 7128 is rated 4.6 out of 5 by 20.
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