Gas to propane generator conversion kit

Hi All; Been 100% off grid since 1983. I use solar and hydro for most of my needs. I have always had a remote start generator of one brand or another to use when we run high draw items. This allows the gen to run everything, plus the built in charger in the inverter recharges the battery's at the same time. I have always coveted the 1800 rpm diesel generators but the cost was to high for me to justify. So I have always just gone with gas 3600 rpm gen sets. For the last ten years or so the quality of gasoline has deteriorated to the point where you need premium / no ethanol / gas to make any small engine run well at all. Sad really gmo corn to ruin our livestock and our fuel supply. I would love to acquire a small steam engine/ boiler and make my power with it... however until that day comes, I chose to convert my current gen set from gas to propane. After researching what was available I decided to go with a product called the "motor snorkel" a tri fuel product. gas/propane/ natural gas. Other products required cutting the roll cage of the generator to allow enough room for the conversion. The motor snorkel did not require cutting anything, it simply replaced the gasket between the air cleaner and carb. Fit rite in ! This makes it simple to remove it from one generator and move it to another. Product allows you to burn any of the three fuels quickly and easily. I had no interest in using gasoline anymore, and of course natural gas is only available in or near a big city. We already use propane for water heating , cooking , refrigeration and on a very small scale for heating..... currently being bulk delivered here for $1.30 gal its much cheaper than gasoline. Best part is the generator never started faster or ran so well !! A real win/win situation! Cost of this kit is not cheap, but the savings will pay for it over time. Being able to move it quickly and easily from this gen set when it dies to its replacement gen set was a big part of my choice. What I got for my $ was the motor snorkel with a large regulator and all the hardware to hook it up. There was a very complete installation booklet that led you thru the install and online or phone help available if needed. For me the install took thirty minutes or less, a real easy install. Little bit of fine tuning on the propane flow control the next morning and I haven't had to make any further adjustments since. Starts rite up below freezing! This is great ! No more wondering how much fuel is left in the tank... no more runs to town to fill 5 gal cans ! Hit the remote button from my easy chair and its running for as long as I need it to. This conversion kit is available online from "US CARBURETION" it was worth every penny to me... it works !

I recently (January 2021) purchased a generator to address my wife's concerns for backup power. After looking at some that were available and thinking of issues I have had with my riding mower I selected one that is dual fuel (gasoline and LPG/propane) and that has a manual rope pull starter (along with the pushbutton electric start). Gasoline goes bad while stored , especially if it has ethanol mixed into it and batteries lose their charge while sitting for months on end.
We purchased a Firman model #HO7552 .
It has the following ratings: Starting Watts 9400(gasoline)/8450(LPG) ; Running Watts 7500(gasoline)/6750(LPG) ; Rated AC Voltage 120/240V ; Rated Frequency 60Hz ; Engine Displacement 439cc; I do not find any horsepower ratings which would also vary depending on gasoline or LPG. Price was $850.00 US.
I never intend to put a drop of gasoline in this thing and will only run it on LPG. This way the fuel system will not be destroyed by the cheap ethanol gas that is sold at the pump. Pure gasoline is available at the hardware store but that is $5 per quart or $20 per gallon. So I have propane cylinders lined up ready to use. They can sit for years without the propane going bad.  
The manual rope pull starter was deemed essential because when it is time to run the generator it will be because there is a blackout since the power is out and that means I cannot plug in my battery charger and charge up the battery to start it with the pushbutton electric start! My riding mower has left me stranded due to no manual rope pull start.
Looking at the picture in the above post I see that your conversion kit looks just like the LPG fuel control system on the Firman generator I have.
At my house I do have Natural Gas plumbed in from the local utility company. I would like to run the generator on the Natural Gas instead of the LPG/Propane since it would be an unlimited fuel supply. Then save the LPG cylinders for a catastrophe when both electricity and Natural Gas were not being supplied by the utility company.
Does anyone know what changes would be required to run this unit on Natural Gas? Is there another conversion kit for Natural Gas?
I will mention that Firman does offer different main jets for the carburetor for gasoline operation at different elevations. Standard Main Jet for sea level to 3000 feet ; Altitude Main Jet #1 for 3000-6000 feet ; Altitude Main Jet #2 for 6000-8000 feet.

Richard Marula wrote:I recently (January 2021) purchased a generator to address my wife's concerns for backup power. After looking at some that were available and thinking of issues I have had with my riding mower I selected one that is dual fuel (gasoline and LPG/propane) and that has a manual rope pull starter (along with the pushbutton electric start). Gasoline goes bad while stored , especially if it has ethanol mixed into it and batteries lose their charge while sitting for months on end.
We purchased a Firman model #HO7552 .
It has the following ratings: Starting Watts 9400(gasoline)/8450(LPG) ; Running Watts 7500(gasoline)/6750(LPG) ; Rated AC Voltage 120/240V ; Rated Frequency 60Hz ; Engine Displacement 439cc; I do not find any horsepower ratings which would also vary depending on gasoline or LPG. Price was $850.00 US.
I never intend to put a drop of gasoline in this thing and will only run it on LPG. This way the fuel system will not be destroyed by the cheap ethanol gas that is sold at the pump. Pure gasoline is available at the hardware store but that is $5 per quart or $20 per gallon. So I have propane cylinders lined up ready to use. They can sit for years without the propane going bad.  
The manual rope pull starter was deemed essential because when it is time to run the generator it will be because there is a blackout since the power is out and that means I cannot plug in my battery charger and charge up the battery to start it with the pushbutton electric start! My riding mower has left me stranded due to no manual rope pull start.
Looking at the picture in the above post I see that your conversion kit looks just like the LPG fuel control system on the Firman generator I have.
At my house I do have Natural Gas plumbed in from the local utility company. I would like to run the generator on the Natural Gas instead of the LPG/Propane since it would be an unlimited fuel supply. Then save the LPG cylinders for a catastrophe when both electricity and Natural Gas were not being supplied by the utility company.
Does anyone know what changes would be required to run this unit on Natural Gas? Is there another conversion kit for Natural Gas?
I will mention that Firman does offer different main jets for the carburetor for gasoline operation at different elevations. Standard Main Jet for sea level to 3000 feet ; Altitude Main Jet #1 for 3000-6000 feet ; Altitude Main Jet #2 for 6000-8000 feet.

Richard there are different types of setups for this. On the portable units you usually have a high pressure to low pressure regulator that screws into the propane tank then a demand regulator near the air intake carb assembly. The demand regulator is really just a diaphragm valve pulled open based on engine vacuum so I would try fitting your nat gas to the intake side and see how it works. It might be too small to keep up but worth a shot. Make sure you have a shut off valve of course.
David

Hi Richard;
The Motor snorkel kit that I used is good for propane or natural gas .
No mention of any changes.   As David mentioned the second regulator is a diaphragm.  
The incoming fuel to it passes thru a "tee"  where a bolt can be run in or out to change the amount of fuel supplied.

Natural gas has less energy per volume. That's the only real difference. With a simple heater/burner, the propane regulator is bypassed and a larger jet (orifice) installed.

In your setup, the goal is reliability. I think I would reach out and ask the manufacturer. I'm sure they would have some insights.

Edit: I missed Thomas' post. Very interesting!

OK, so I re-read the post by Thomas Rubino and saw that he mentioned US CARBURETION is where he was able to get his conversion kit. The website is http://www.uscarburetion.com/ . Lots of good info there and answers to FAQs.

I gave the Firman Helpline a call and talked with Christopher. I let him know I have one of their dual-fuel Gasoline or LPG generators. I asked if they offer a conversion kit to Natural Gas. They do not offer a conversion kit. He said that the Natural Gas burns hotter so he did not think they would be offering one in the future either. Has anyone experienced high temperature issues or engine damage due to high temperatures from using Natural Gas?

I found the chart on this link is helpful for knowing what pipe size is needed to supply adequate Natural Gas to the generator.  http://www.uscarburetion.com/natural-gas.htm

I went to the Firman website  https://www.firmanpowerequipment.com/ and noticed they do offer two generators that are Tri-Fuel (Gasoline , LPG/Propane , Natural Gas). Both have a 439cc engine. They state "Our Max Pro Series 439cc engine runs cool and efficient thanks to its Phoenix Fat Head Block."
One of the generators 9400/7500watt is only offered through Costco and no price was shown. The other is 10,000 watt and listed at $1,299.99. So it sounds like they are identical, or very much so.

Richard Marula wrote:I gave the Firman Helpline a call and talked with Christopher. I let him know I have one of their dual-fuel Gasoline or LPG generators. I asked if they offer a conversion kit to Natural Gas. They do not offer a conversion kit. He said that the Natural Gas burns hotter so he did not think they would be offering one in the future either. Has anyone experienced high temperature issues or engine damage due to high temperatures from using Natural Gas?

Hm! That sounds odd to me. Maybe their calculation assumes that a richer NG mix would be needed to maintain the same power output?