We have several propane machines, forklift, scissor lift, etc. None of them like to start! Once running, they are great. The fork will start after about 5-7sec of cranking. Same with the scissor lift. Now dealing with a boom lift that just refuses to start without some spray, which will become a problem when in the air! What is the typical way to get these going? I don't recall ever seeing a choke on propane.
On our forklift at work we just hold the accelerator to the floor until she fires but we don’t live in an especially cold climate (only down to the 20s)
On a propane engine its not a choke but a primer. Typically its a button in the middle of the vaporizer you push. There are also electric coils that fit around the primer button to enable remote primer. Propane engines are very sensitive to vacuum leaks due to the engine "sucking" the propane from the vaporizer.
Probably need to rebuild the regulator.
On the forklift for sure, the regulator is brand new. I built a lot of that machine and I know the intake side and LP is tight. I like stuff "ready to go"..... That reg does not have a primer nor does the boom lift, but the scissor certainly does and it will fire right up with a "prime".... I might have a spare wire in the harness I can use but as you can imagine, the wiring goes all over through the scissor structure to get to the platform. Do LP engines just need a primer? Ran so many LP forks that fire right up! I want to know why! On the fork, I certainly hold the pedal to the floor, but it still takes too long and frustrating when working, causing us to leave things running more than needed, which just burns off fuel and hours.
How cold?
Doesn't matter. Right now 80F. They all just need prime to start, and not one of them has a priming function.
Generally, propane stuff needs no priming or choking to start. I will spare you the boring details of why it is different than gasoline. Although a little choking and/or priming does sometimes help in cold temps. Various equipment has various means of safety shut off so it may take a short while for this to act or be overcome or whatever. Another difference could be that some engines have carburetors, and some have mixers with moving parts. Mixers should theoretically start easier, not being as dependent on (weak when cranking) air flow through a venturi.
In my experience, and I'm certainly no expert on the stuff, but propane engines are in my opinion the most finicky for the mixture to be "perfect", that includes both starting and running. Most vaporizers/regulators now days don't really have mixture adjustments to "dial it in", like all carburetors EPA laws have really restricted what you can "tweak" on them. With that said, my advice, don't try to "wing it" with a "might fit will fit", pay the extra bucks for the OEM replacement regulator, whether Cat, JLG, Clark, whatever. And don't bother with rebuild, I've wasted too much time with that, just replace. And that includes the vacuum lock off if it has one. Older regulators had a primer button for starting or a solenoid to operate the button from remote locations, like an operators seat or aerial platform, those days are gone, again, thank you EPA. Probably the best for starting is the Beam regulators, they have an adjustment screw they call "idle", which it's really not, it actually assists in starting if it's adjusted properly. But again, my advice, if it's aged, replace it. And replace with OEM parts. Propane is picky, and "will fit" don't always fit.
I used to build race engines so I have worked with nearly all fuels from Nitro down to 87. I have these engines tuned to run good, and they do, but it's all about getting that mouthful of fresh gas to fire. But this thread did remind me about some guys in CO that are propane specialists. They might have some ideas. One that I recall on the scissor is the damn reg is like 3ft from the engine! And always the feed pipe for LP "gas" is quite large. Part of these issues is having second hand equipment that "special people" worked on. Usually when I see wire nuts in the field, I run.....lol
Propane is no big mystery, hold the throttle open some and should bust right off, keep the throttle open as engine builds heat and the vaporizer will soon have it idling up fine on its own.
Probably not your issue, but some years ago, they switched suppliers of propane. It was a bit cheaper. We had just purchased our Nissan forklift. It always started hard, even in the summer. Now it only gets used around the shop, so a tank lasts a long time, but it started hard, and the fumes were strong. Some time later, the united rentals guy, at that time it was Atlantic rentals, he was at the shop dropping off a manlift. He noticed the name on the tank on the forklift. He asked how the machine worked. He said they used to buy propane from the same supplier, and had a lot of trouble with the equipment. Turns out the guy bought prefilled tanks that came from out of the country. Swapped tanks from the manlift to the forklift, and after a couple starts, it ran clean, and started every time with a touch of the key. They went back to the company we had before, and have not had issue since.
When was the last time the valves were adjusted on any of these engines? Mixture ever adjusted with a Manometer hooked up? Ignition systems gone through?