Something not often covered but far too often discovered while at camp is that your appliances have some sort of issue.
You are most likely issue is going to be a leak of some sort. You should know how to detect and possibly fix those leaks.
With liquid-fueled appliances leaks tend to be readily apparent. On stoves you typically see fuel pooling up in the little recess where the pickup tube comes out of the tank. Or the tank simply will not take pressure due to either a bad pump or a bad cap.
If you see fuel pooling chances are you will likely be able to see where it is coming from. The most likely culprit is the packing behind the valve stem nut this is a piece of graphite that does tend to go bad over time. To fix this you can try to turn the valve wide open and then using 1/2 inch open end wrench simply snug the nut down a little at a time no more than 1/8 turn.
If it is a bad cap he will smell fuel leaking from around the cap and quite possibly see fuel leaking down the tank near the fill cap The fix there is to Simply replace the cap.
A bad pump is usually do to the leather cup getting dried out and shrinking you can try rehydrating and swelling that cup by removing the pump and soaking the leather cup in vegetable oil for about an hour or so. Then reinstall the pump and try generating pressure in the tank. If that fails a new pump repair kit is in order they are inexpensive and readily available get many retailers.
Propane and butane offer a unique problem. Since we are addressing car camping in this post I'm not going to go into the issues of butane as it is a very Cod fuel to use for out of the car camping and more commonly used for backpacking.
Determining where or even if propane is leaking can be far more complex then determining if liquid fuel is leaking and it requires additional equipment to run a test. You will need a household spray bottle filled with soapy dishwater the idea here is to spray around any and all joints and fittings where the propane runs if the propane is leaking the soapy water should bubble up so make sure you use enough soap and that it is the kind that gets very sudsy.
To run the test make certain you are outdoors and no where near any sort of ignition source then simply attach your fuel bottle or line to your Appliance and spray down the joints where the bottle screws in where the valve that operates the fuel flow is and look for any bubbles. Open the valve slowly and continue the test spraying around the valve until the valve is all the way open and then close the valve make sure you don't see any bubbles other than what you expect to see was just soapy water.
Depending on the manufacturer and the model of the propane Appliance in question you will likely need to Source up whenever components you find leaking if they are available. We have found with Coleman, Zodi and Century appliances that Parts availability tends to be fairly good. Other brands can be hit-or-miss. Sometimes all you need to replace is a simple rubber or cork gasket comma sometimes it's an entire valve assembly or even a regulator. This is just part and parcel of taking care of your equipment.
It should be noted that with proper care there is no shortage of late 1940s and early 1950s camp stoves that have been cared for and lovingly used by generations of the same family. The build quality today is no better or worse than has been in years past thankfully. With appropriate care and maintenance you can expect you're Camp appliances to provide great service literally for decades.
It should be noted then we our cells have had to replace a valve stem packing on our Coleman 424 stove and a pump rebuild kit on one of our premium fuel lanterns. We also have a leaking fuel control valve on a Century single burner camp stove that we got in the 1980s. We are not planning on fixing that particular stove since the replacement part cost more than the stove.
Hopefully the information we've provided here today has been of some value to you. Before you fully rely on this information we encourage you to seek out Diagnostic and repair information from your specific Appliance vendor. They can be very good at helping keep your equipment running in top condition with maximum safety.
Somero you've got the information hopefully you've taken care of your equipment so get out there and find your own Road Less Traveled.