# Auxiliary fuel tank generator



## Andrew Schmitt (Jul 15, 2019)

I recently bought an older model Coleman powerhouse 2500 powermate generator, it’s ran by a 5 hp Briggs and station engine 135212, it runs great however the fuel tank is only 1 gallon and can get maybe 3 hours with running my camper, I am wanting to put an auxiliary fuel tank on but the problem is that this model is not gravity fed in the first place, the fuel tank sits just below the carb and a stem goes down into the tank from the carb so all the auxiliary tank setups overflow the tank and then keeps going untill it comes out of the top of the carborator, is there any aux fuel tanks I can use on this tank/carb setup that will fill the tank to under a gallon and stop and BE SAFE. Thanks!


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## KRE (Nov 29, 2011)

I don't believe your going to find a bigger tank. Thinking this thru your best bet might be upgrading to another unit, as about your only safe option is installing a float valve. This can be done in many ways, but not cost effectively that I know of


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## RedOctobyr (Aug 8, 2018)

Agreed that it seems like a difficult challenge to solve, given the type of carb. I'm picturing the kind that used to be on top of metal tanks, on some Briggs-powered mowers I had from probably the 80's or early 90's. 

You could establish a siphon between your tank, and an external gas tank. But they'd need to be positioned so that the external tank could never be filled above the top of the tank. You'd have to create the siphon every time. And no matter how big the external tank, you'd only get to use the volume that was between the top of the generator's tank, and the bottom of its tank (that's the height that the siphon could work). So even if it was a 5 gallon gas can, maybe you'd get 1 usable gallon from it, just making up a number. And you'd need to have a small vent in each tank, to avoid drawing a vacuum. This risks fumes escaping, causing a fire hazard. 

So, it *could* be done. But I think it would be a clumsy, poor solution, and it wouldn't offer much benefit.


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## jkingrph (Sep 18, 2017)

I don't know about that particular model. I have a Honda EU2000 and have an auxiliary tank. I used an aftermarket cap which allows it to suck fuel out of the auxiliary tank into the onboard tank. The auxiliary can be the same or slightly lower level, than the generator. I honestly do not know what would happen if it were higher. Apparently there is enough suction to pull the gasoline out of the auxiliary tank which in my case is an outboard motor tank, into the generator tank which then feeds the carburetor. Mine is rated to run up to 8.1 hours per gallon so with what i think is a 6 gal auxiliary I could in theory go up to about 50 hours, probably not near that under a moderate to heavier load, but probably well over 30 hours.


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## exmar (Jun 29, 2015)

Asking a question and not trying to hijack this thread. Know nothing about generators for camping, just looking in stores and online, they seem to be very compact and ...."suitcase".... styled which would seem to limit size of the tank. Open frame generators seem to be designed to get 10-12 hours at half load, but they're larger, heavier and noisier which would be an issue at a campground I guess. My question is, isn't this a "catch-22," in that you want something compact which is easily stored and transported and have to accept that every three hours or whatever, have to refill, check oil, etc.? 

Speaking of run times, a buddy asked me to look at a genset he was thinking of buying for power outages. I looked online and it seemed to be a typical 5KW. What did catch my eye was it advertised "18 hour run time on a tank of gas." Reading further, 18 hours at 25% load, wonder if that's going to be the new standard or just creative advertising?


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## RedOctobyr (Aug 8, 2018)

Like jkingrph, I have an EU2000i, and I made an external 6-gallon tank setup for it, using an outboard engine tank. It's a nice way to get the best of both worlds. The portability of just the EU2000i is great if you are OK with the 4-10 hours claimed for a tank, depending on load (1/4 load, to full). And I can hook up the external tank for power-outage use at home, for about 28-70 hours. 

Note that typical open-frame "contractor" generators are different functionally than inverter generators, which tend to be the small, suitcase-style ones. Inverter units can produce cleaner electrical output, and they can also vary their RPM based on the load. My EU2000i will go down to 3000 RRM (99cc 4-stroke) with no load, up to 4400 RPM will a full load, or 5000 RPM in an overload situation. A traditional generator must always run at 3600 RPM, regardless of load, to produce the proper 60 Hz power. So some fuel benefits come from this ability to slow down the engine under a lighter load, and also probably you might be able to use a smaller engine. If locked at 3600 RPM, my 99cc engine likely wouldn't produce enough power to make the full 2000W. 

jkingrph, the one time I needed to use it so far, I put my external tank up on top of a 5-gallon bucket, to help the generator draw from it. It shouldn't have been necessary, I think I failed to prime the line properly on my first attempt (when the engine stalled after 15 minutes or so), and I may have had the internal tank's fuel level too low. But for attempt # 2 , I raised the height of the external tank, and it ran smoothly after that.


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## exmar (Jun 29, 2015)

I'd forgotten about the variable RPM on inverter types. Thanks for the explanation.


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## jkingrph (Sep 18, 2017)

jkingrph, the one time I needed to use it so far, I put my external tank up on top of a 5-gallon bucket, to help the generator draw from it. It shouldn't have been necessary, I think I failed to prime the line properly on my first attempt (when the engine stalled after 15 minutes or so), and I may have had the internal tank's fuel level too low. But for attempt # 2 , I raised the height of the external tank, and it ran smoothly after that.[/QUOTE]

That makes sense. The EU2000 draws the fuel from the auxiliary tank via vacuum suction. I would think it would make sense to have it the same or a little higher than the internal tank, and start with a fairly full on board tank so it would have time to create enough vacuum in the lines to pull fuel from the auxiliary. The one time i actually used mine I ran it on propane, I had installed one of the Hutch Mountain conversions and it ran great. I figured on these small units i would set them up for dual fuel, as it is easier to get gasoline than propane. I do keep several 5 gal propane bottles and a three of the larger 10 gal types, so along with the gasoline i keep for mowers ect, i can probably run the small gen sets well over a week if needed without seeking out more fuel.


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