The burner valve controls the flow of fuel to the burner from the burner fuel system. Opening this dash-mounted valve permits fuel (kerosene) to flow to the burner. The valve is located between the burner fuel system pressure tanks and the steam automatic.

Drivers have made the mistake of leaving this valve open after the steam automatic has stopped fuel flow to the burner and compounding that mistake by leaving the vicinity of the car.  Later, often with the driver nowhere around, the boiler pressure drops sufficiently that the steam automatic allows fuel flow to the burner.  If the car has been sitting idle and the vaporizer has cooled, the fuel will not be vaporized and liquid fuel is directed from the burner nozzles into the burner mixing tubes.  If the pilot is burning the vapors from the raw fuel soon ignite and the whole bottom of the boiler is now on fire and that fire is being fed by additional raw fuel coming from the fuel system.  Paint is scorched and burned off and generally a calamity results.

The burner fuel system pressure tanks generally hold two quarts of fuel. It shouldn’t take much imagination to visualize what two cans of charcoal lighter fluid would do if dumped on a hot charcoal grill!  That’s the same amount of fuel that would be fed to the Stanley burner fire just described. Needless to say most wooden-framed (and in earlier cars wooden bodied) Stanley’s would not survive.

If the car is going to be stopped for a period of time this valve should be closed prior to stopping the car. This should be done for two reasons. First, if the car is going to be idle for a period of time (such as at a show) the boiler pressure should be allowed to drop to 400 to 500 PSIG before the car is stopped. This insures that the steam automatic is calling for the burner to fire. When it comes time to reignite the burner after it has been off for a period of time, the steam automatic needs to be calling for the burner to fire.

A review of the piping diagram shows that the steam automatic is the last valve in the fuel flow to the burner. This is to prevent the burner from firing if the steam pressure is near or above 600 PSIG (which can happen is the pilot is burning too strongly). If the steam automatic has closed off fuel flow to the burner because the boiler pressure is at operating pressure then opening either the firing up valve or the burner fuel valve will have no effect in lighting the burner. Only after the car has been driven a short distance will the steam pressure in the boiler drop sufficiently to allow the steam automatic to start fuel flow to the burner. At this point it becomes a great deal more difficult to ignite the burner successfully while also trying to drive the car.

It is also desirable that any fuel under pressure in the piping between the burner valve and the burner is vaporized and burned before the car is stopped for a period of time. If the boiler pressure rises to where the steam automatic stops fuel from flowing to the burner, there will be fuel under pressure trapped between the steam automatic’s fuel valve and the burner fuel valve. If the burner fuel valve is subsequently turned off after the steam automatic has also stopped fuel flow to the burner, there is a slug of fuel trapped at pressure between the burner fuel valve and the steam automatic’s fuel valve.

After a period of time the steam pressure of the boiler may drop sufficiently that he steam automatic calls for the burner to light. The slug of fuel under pressure runs into the vaporizer. If the vaporizer has cooled this fuel doesn’t vaporize quickly and it is doesn’t have a constant pressure to push it out the nozzles. Over time the fuel slowly vaporizes and gas vents from the jets. Depending on how tight the pilot access door is and other factors this vapor could ignite with a loud pop and startle anyone that happens to be nearby the car. As the fuel is only partially vaporized it tends to take on an unpleasant raw kerosene smell that most find objectionable.

One thing the Stanley driver must pay attention to when operating the car is that the firing up valve and the burner valve are never opened at the same time. A quick examination of the piping diagram reveals that the firing up valve and the burner valve both share common piping between each valve and the burner. This means that should the firing up valve be open or even partially open when the burner valve is opened, the higher-pressure fuel from the burner fuel system will flow into the lower pressure fuel of the pilot burner fuel system. The result will be a building of pressure in the pilot fuel system above it’s normal 25 to 30 PSIG operating pressure. The pilot will start to burn a more vigorously with the increased pressure and there is the chance the pilot fuel tank or some of the pilot fuel system piping could rupture or leak and spray fuel that could ignite.

Additionally the pilot fuel will become contaminated with kerosene making it much more difficult to vaporize. Since the pilot burner’s vaporizer is designed for the easily vaporized pilot fuel (its only a few inches long and not the nearly 8 feet long like the burner vaporizer), when the kerosene contaminated pilot fuel reaches the vaporizer it will not be heated into a gas but will end up being discharged from the pilot nozzles into the pilot mixing tube. In a short amount of time the pilot burner will backfire due to being flooded with liquid kerosene.