Generator dual fuel conversion

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Ashful

Minister of Fire
Mar 7, 2012
20,075
Philadelphia
I have a 6800/8500 watt generator with a Honda GX390 engine:

https://www.homedepot.com/p/PowerSt...with-Honda-GX390-Engine-PS906811P-H/204401587

It works great, but at 10 gallons per day, is a hassle to keep fueled. And even though I do a good job of keeping stabilizer in any fuel remaining in the tank, and draining down the carb after each use, there’s always the concern of a fuel system malfunction when I need it. We’ve also had one situation, where all local gas stations were shut down for an extended period (the eye of hurricane Sandy went right over us, mass destruction).

So, I see a lot of folks offering propane conversion kits on-line. I have a 500 gallon propane tank in the back yard, which we currently only use for a direct vent heater in our garage (run only a few days each winter) and a gas log fireplace on the patio (also only run a few evenings each summer). I could easily tee off the propane line in the garage, to run a line to the generator, which I park directly outside the garage to back feed the house.

However, most of the kits I see involve removing the carb, and putting a spacer with the propane feed in behind the carb. This, more often than not, means cutting the frame on this style generator. It would also mean fabbing up some new bracketry to support the air cleaner. I’d rather not do that, if I can find one that might be of the lowest profile possible.

What have you folks done? Any experts in this area?

I’ll also have some questions on the best type of lines and quick-disconnect fittings, to get the propane feed hooked up (must be flexible hose), when I get to that stage.

Thanks!
 
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interesting looking at getting a gen and did not know this was a kit you could do..
 
One guy on another site just plumed the gas line into the fuEl bowl of his existing carb (the drain plug would be an excellent candidate) shut off the gasoline, once the engine is running, and turn on the propane valve.
You will loose some power, just because propane doesn't have as many BTU's, but if your loads are about half of the generator capacity, which is a good place to target, it should be fine
I ran a scissor lift before that was dual fuel, and that was the way you transferred from gas to propane and back
 
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One guy on another site just plumed the gas line into the fuEl bowl of his existing carb (the drain plug would be an excellent candidate) shut off the gasoline, once the engine is running, and turn on the propane valve.
You will loose some power, just because propane doesn't have as many BTU's, but if your loads are about half of the generator capacity, which is a good place to target, it should be fine
I ran a scissor lift before that was dual fuel, and that was the way you transferred from gas to propane and back

I’ll look into that. I use that drain, which is just rough thin casting and not currently threaded, to drain bowl before storage. But, I could likely install another fitting elsewhere in the bowl, if this is known to work.

On BTUs, yes that may be an issue, and part of why I don’t want to lose the gasoline option. One would hope their engine is oversized enough, that the loss of switching to propane wouldn’t be an issue, but that does not appear to be the case on this unit. No surprise.

Isn’t @DAKSY an expert on all things propane?
 
<Isn’t @DAKSY an expert on all things propane?>

Expert? Not even close.
My knowledge is limited to NG & LP burning, zone-heating appliances & gas grills.
I have not dabbled in gasoline to LP conversions (yet!)
 
you will need a regulator inline prior to introduction to intake manifold. can't really help beyond that, as my genny is propane only. somehow you need to accomplish an air fuel mix ahead of intake. I do not know about piping to bowl on carb- never heard about that before.
 
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you will need a regulator inline prior to introduction to intake manifold. can't really help beyond that, as my genny is propane only. somehow you need to accomplish an air fuel mix ahead of intake. I do not know about piping to bowl on carb- never heard about that before.
Yeah, that's new to me, too. The standard kits use an adaptor plate between carb and intake, called "adapter" in the photo below:

[Hearth.com] Generator dual fuel conversion


The issue for me is that adaptor plate seems to cause the air cleaner to interfere with the frame of the generator. You see some folks just cut the frame, which must make it very weak for moving around. I could fab up something a little nicer, but not without a bunch of work.

I also just found this, which I had not seen before. I'll have to search for install info:

https://www.amazon.com/dp/B06XJ5R9CX/?tag=hearthamazon-20
 
Would be pretty easy to weld up a lil "dog leg" around the cut frame, no?
 
Would be pretty easy to weld up a lil "dog leg" around the cut frame, no?
Yep, got MIG. But five minutes with the grinder and welder always seems to turn into two days of disassembly, fitting, fabbing (other bracketry involved), masking, priming, painting, etc. Trying to make this a simple bolt-on project, if I can. Got enough other irons in the fire to keep me busy, at the moment.
 
I just bought a 5 KW (continuous) dual fuel generator for just that reason. I've had problems with all carbs getting gummed from non-use and that's when you need a generator most. So, dual fuel from the start and the thing will never see gas, just propane from BBQ tanks.
 
can anyone tell me how long does a 20 pound tank last on a 5 thousand watt generator? my generator has a 11 hp motor
 
with all the options that gen has that is short money