Does anyone here know from propane powered engines?


Active member
I've had my hands full for months now, so much going on, so little time to post, maybe I'll do an update soon, but onward to today's topic.

I have an older (15+ years) Generac Guardian 30K propane generator.
It's been a real champ. Other than oil changes and battery replacements, this thing has been beautifully reliable, and trouble free.

I fear we have reached the days where everyone is too young to no shit about anything.
If you can't plug a phone or a computer into something, folks are just plain lost.
Then add the current state of technology, whereas if YOU can't plug your phone or confuser into it, you're just about as screwed too!

Me? I'll still Macgyver the hell out of anything and make stuff do what it was never intended for if I have to.
I don't care how many usb ports or computers you have hooked to it, or whether it's tethered to some orbiting space module floating 22,000 miles above your home, an engine still only needs three things to run: Air, fuel, and spark.

I don't use this power plant real often, because it's probably large enough to run 3 homes, and can put a hell of a dent in a propane supply when under a good load.

But as shit would have it, we had a good storm last Sunday which brought us an unprecedented amount of snow that decided to hang around.
No sun, and a foot and a half of unflavored snowcones covering everything, including my panels, the house batteries started getting low, so I headed out to fire up the big guy.
It cranked, it cranked, then it cranked some more, but didn't feel like starting.
I just put a new battery in it a month ago, and I have hundreds of gallons LPG on hand.

Not wanting to run either the starter or the new battery into the ground, I gave up for a bit.

A few hours later dawning my nanook outfit, grabbing my favorite baby seal, and wishing I had a snowmobile, I trudged the 50 feet back out to the generac.
Normally it will fire inside of 10-20 seconds, and previously as of late, it seems to be taking a little longer now that I think about it.
I let her crank for about 30 seconds with no response.
Against my better judgement, I was seriously considering grabbing a can of ether.
At the time, feeling a bit despondent about the whole situation, I wasn't sure if I was going to huff the stuff, or use it to try and start the generator.
I gave minutes pause to my quandary, and hit the start button again, and again she just cranked.
I looked to the the sky, with a tear forming in my eye, and shouted, "Really Dude???!!! Do I deserve this???"
About that same second, 30,000 watts of pure power came to life.
I smiled, shouted thank you, and headed inside.

I gave the batteries a solid 4 hour equalization charge, then shut it down.
It ran without a hitch, and purred like a kitten.

About halfway through the following day, as I was reading stories about big trucks and cars needing to wait in line, or make reservations to get into the "Comedian" on I-40, it became obvious that the sun's return would be hastened by more clouds bearing free slushies and unassembled snowmen, and I should probably give the acid laden lead plates some more angry pixies.

I headed out to the genset, and the wife kindly offered to climb to the roof to sweep the snow off the panels.

Much to my dismay, the old girl (generator, not the wife) cranked away again with no signs of getting out of bed.
So the other 2 of us decided that since the third was going to lay in bed all day, we'd just as soon do the same, and did.

The following day the sun broke free delivering many ions and electrons, and I rested easy.
A day or so later it was warming up and the snow began to melt. The genset was still heavily on my mind, and I decided it needed some trouble shooting.
I looked for any loose connections, or signs of rodents attempting to increase their copper intake, and found none.

More cranks, and more of the same nothing.
I gave it a short shot of ether, and it acted as though it enjoyed it, letting me know that at least one of the major elements required for its operation was present; spark.
I hate using ether though, the horror stories are vast and wide, and I'd really hate to launch the heads off this nice little Ford 4 banger.

Next, I decided to make sure that propane was being delivered past the dedicated regulator designated to this unit.
There is a gizmo that looks a little like a fuel pump between the propane companies supplied regulator, and the line to the engines carb. It has an electric two wire gizmo attached, which I'd venture to guess is a valve or relay.
I opened the line between the two, and the smell of rotting corpses emerged quite fragrantly, letting me know the second element needed was present, at least that far down the line.
I let it bleed for a little while longer believing that if maybe there was some air in the line that it would be expelled.
I tightened the hose back up, and gave the starter motor another round of cardio.
Nope, still not going to start.

I pulled the air filter, (which I'll admit is due for replacement) for a look and a sniff in the carb.
The intake was clear, but the odor of any propane wasn't.

Now here's a bit of my downfall, I have little practical hands on experience with LPG carbs, but it can't be that hard.
I operated the electric choke mechanism by hand, and watched it's operation as I cranked the engine, and it appeared completely functional.

Needing a break, I decided to hit the webs, make some calls, and see what I could learn.
The first thing that I learned is apparently none of the techs at generac were even alive yet when this was built.
The concept of hands on "go, no go" testing was lost light years before they were even a lustful thought in either of their fluid swapping progenitors cranial crevasses.

On top of this, google search has really stepped up their game lately, for it appears the only thing you wish to learn or ask about, has never been learned nor asked about by any other soul who ever dragged knuckles on this planet.
But this only becomes apparent when you reach about the 15 page and see nothing but the same ads over and over again that have not one iota of anything to do with what you are searching for.

While trying for the bonus round with the techs at Generac, one of them offered to put a call in to a local "Distributor" to see if he could help.
The guy called, and as we spoke, it was painfully clear that this guy didn't know a sparkplug from a waffle iron.
He later admitted that he was only a distributor, knew a little about electrical installations in residential dwellings, but didn't have a clue about the operation of anything beyond his iphone and his microwave, but if I was willing to wait a few days, he would gladly drive the 5 hours from Timbuktoo, have a looksee, charge me for the trip both ways and try to take a guess at how many parts he might need to order, to charge me again to come back and install quite possibly in the end an entire new generator.

I kindly thanked him for absolutely nothing, and went out to troubleshoot some more.

Knowing I had spark, observing that I was breathing, indicating the presence of air, the only thing it can possibly be is fuel.
My next thought was to remove the fuel inlet line to the carb, stuff the hose up my beak, crank it over, and see if fuel was making it to the carb.
As I turned for yet another trip to the tool dept, something caught my eye, rang a loud school bell, and lit the bulb above my head.

What I had just spotted, and had completely forgotten that I had, (due to the absurdity of even owning one in the dry arid desert,) was a brand new propane weed burner that some other scared to shitless to use it friend of my wife's had given her.

I picked up the burner set up and walked it over the generator.
I once again removed the air cleaner, I then turned the valve on the 5 gallon tank to its on position.

I held the business end of the brushfire beast above the carb inlet.
With one hand on the let 'er rip lever, and the other on the generator start switch, I looked heavenward and hoped this wasn't about to be the stupidest fucking thing I had ever done in my life.

I cranked the engine, and blasted a torrent of propane/air mix down it's little gullet.

The genset sprang immediately to life, and ran for hours without so much as a hiccup.

So that reminds me, I had a question when I started writing this;

What do you think I should do?




Jerk in a Hawaiian Shirt & SNOWCAT Moderator
Staff member
GOLD Site Supporter
I was going to suggest to look at everything between the Regulator and the carb.

I had an old tri-fuel generator. Propane/NG and gasoline. Every time there was an issue it was between the regulator and the carb.


Well-known member
GOLD Site Supporter
I think your problem might be in "the little thingy with two wires" which sounds like a solenoid valve that releases LPG to the carb or the thingy that sends 12 volts to it. Why it starts working once you prime it, I do not know unless the engine vibration shakes it enough to make the valve open.


Proudly Deplorable
GOLD Site Supporter
Quite a story Joe well written. I think mla20fus is onto the problem. As I read your prose that shut off butterfly/valve came to mind.

It may have been mechanically stuck or not getting a signal to open. That burst of high pressure air/fuel may have been all it needed. Were it an electrical issue, the unit would have started but, I doubt it would have continued running.


Well-known member
GOLD Site Supporter
Joe, how cold has it been? If it has been really cold perhaps the propane hasn't been gasifying properly or hasn't been producing enough gas at sufficient pressure to start the generator. When I worked in Wyoming during the winter I used to see guys starting fires under their propane tanks in order to get it to gasify. I watched it from about 100 yards away. It made me nervous as hell. Perhaps the cold caused the propane gas to liquify in the lines and restrict flow. I'm saying this because the problem seems to be associated with the cold weather that you are experiencing.


Active member
Thanks for the replies everybody!
To answer a few questions;
It's been cold here, at least for my ass, but it hasn't been below zero or anything like that, maybe the lowest it's been is maybe mid to high twenties, but again, that doesn't go on day after day, so I'm not so much suspecting the temperature, but what do I know; I'm the one with the problem.

I've messed with smaller propane regulators, but haven't had much luck, except I do know they fail.
One of their failsafes is that they won't let gas through if the pressure feeding it is too high.
But for the most part, the little ones for BBQgrills and stuff, I just 86 'em and buy new ones.
The one in question isn't as big as what you might see on your house or a large tank, but it is way larger than the one on your webber.
If push came to shove, I was thinking about bypassing it since there is a big one inline on the tank, and most probably one inside with the switch or relay on it.
I was considering jumping it to see what happens, but you gotta be careful with those unless you know the voltage and polarity and all.
Don't want to send 13.5 down the line to a 3 volt switch.
There IS a good sized box inside this thing with relays, fuses, a couple boards full of chips, some idiot lights and other stuff, so I do want to be careful.

One of the things I don't know, is if the carb stays under pressure all the time, or hold a prime, or has a reservoir of any sort.
I didn't try it today, but I'm gonna put my money on that little frappastat with the two wires, or the propane companies regulator.
Which really has me wondering, if it just went bad, or there really is a reason that it doesn't want to open because of something else down the line like the inevitable oil or water sensor or something.
But I'll be damned if I'm gonna pay some asshat five hours out and back to figure it out.
maybe tomorrow or the next I'll look er over again.

Until then.....

Oh, and an extra thanks Frank! ;-)


Well-known member
GOLD Site Supporter
What ETF said, I have the same problem with propane forklifts in the winter, the regulator freezes. When you get it running long enough the engine cooling water is routed through the regulator keeps it from freezing again.


Well-known member
GOLD Site Supporter
You could connect a VOM to the wires going to the solenoid valve to see if it's getting power while trying to start it. I'm guessing it's 12v if the starting system is but the meter would tell you if it's getting power and the voltage. If it's getting power try tapping it with a screwdriver handle while cranking it.


I have two 100 pound propane tanks hooked together by an automatic switchover regulator and when it would get cold, it would freeze up. I eventually hooked up just one tank with a normal regulator and it was fine and didn’t have any issues with it freezing up. The other part to this was for the first few years it was fine then in later years is when the issue arose. I’m wondering if your system isn’t having the same issues as far as it freezing up the line.


Active member
I have two 100 pound propane tanks hooked together by an automatic switchover regulator and when it would get cold, it would freeze up. I eventually hooked up just one tank with a normal regulator and it was fine and didn’t have any issues with it freezing up. The other part to this was for the first few years it was fine then in later years is when the issue arose. I’m wondering if your system isn’t having the same issues as far as it freezing up the line.

I don't know... maybe my generator is as acclimated as I am to the Arizona desert.
I grew up in Minasoda, then gravited south to the Colorado mountain area, after giving a very solemn goodby to Ollie and Lena, vowing never to return.
Winters weren't nearly as brutal in Colorado as they were in the great white north, but there sometimes comes a time in a man's life where he swears if he ever has to chain up a vehicle again, it really will be the coldest day in hell.

It was southbound again, settling in the much lower mountains of the Arizona high desert.

I hate the cold, and snow even more.

I used to brave those -20º days with their 90º below zero windchills, so really, I shouldn't think a few days or nights of 28 or 30 degrees should considered brrrr farkin' cold, but I do.
Maybe the generac feels the same way.
It was about 55º yesterday, if I remember correctly.
I decided for the hell of it to hit the start button as I passed by, and it started as normal.

I'm a big fan of the don't fix it if it ain't broke club, but knowing there may be a broke in the near future always bothers me, so I'll probably try to find that regulator switch setup and order one to have on hand.


Just Plinkin Away the $$
Your generator should have a vacuum operated diaphragm in the intake (beyond the choke plate ) and sometimes in the fuel mixer that is the safety that shuts off the constant supply of fuel to the engine if it quits running, in the event the genny stops for some reason.

Some lp regulators have a vacuum line to the fuel regulator from the fuel mixer or the intake manifold post mixer to shut the fuel off sans vacuum, others use a diaphragm actuated electrical switch that goes to a electric fuel solenoid in the line from the tank.

LP hates cold weather and doesn't want to vaporize in chilling temps, you could also back your vehicle near the generator and run a hose off the exhaust and stick it through an opening in the generators enclosure to bring the temp of your generator. Give it about 20 minutes, shut your vehicle off and remove the hose from the exhaust and gen housing, give it a minute for the fumes to go away and crank it up.
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