Why did Stanley discontinue the use of the fuel pressure retaining valve on the condensing cars? Most all of the non condensing cars had one installed. The 1913 Stanley operating instruction manual still shows one being used. Could the fuel pressure retaining valve have been discontinued because by 1915, Stanley had went to the slower speed pumps driven in a deeper pump pit and they also changed from gasoline to Kerosene? On our 1914 Stanley 606 when I bought it 25 years ago, it didn't have a fuel pressure retaining valve on it. After being stuck several times with a fuel pump that had lost it's prime while sitting, I soon installed a fuel pressure retaining valve, and I have had no problem since. The vapor lock problem of the fuel pump was more pronounced while using straight gasoline than while using kerosene.



Edited 1 time(s). Last edit at 07/20/2009 03:49AM by SSsssteamer.

I don’t consider that they did. On condensing cars the center valve under the drivers seat shuts off and retains the air pressure (a separate air tank) to charge the main fuel & pilot tank.

The difference is in the condensing cars they separated the air tank from the main air & fuel tank with the three valves because of the two fuel systems they moved the valve between the two tanks instead of after them which does allow the air over fuel to leak back to the tank if your fuel pressure regulator or the checks leak.

Rolly

In reading the 1917 operator's manual, I now see that they still used the pressure retaining valve through 1917. The pressure retaining valve is used to retain the fuel pressure in your main fuel pressure bottles while parked. If the pressure retaining valve is not turned off while parked, the fuel pressure can leak backwards through the fuel pumps leaving your fuel system vapor locked. With hot fuel lines, gasoline can vaporize and as a vapor, can leak backwards through the fuel pump ball check very easily. If the Stanley is to be parked anymore than 5 minutes, the fuel pressure retaining valve should be turned off. To go again, it has to be turned back on, or all fuel pumped will be bypassed back into the main fuel tank. The later model 735 had two pilot/main hand air valves located under the toe board. Between these an air hose was attached to charge the fuel systems. The later model 735's came with an air storage tank from which a third valve located between the two former valves was used to supply the air to the two fuel systems. On the later model 735s, the three valves were located at your heel board. The hand air valves are not to be confused with the fuel pressure retaining valve, as they are for different uses. Why did the model 735 Stanleys and later discontinue the fuel pressure retaining valve? I think that it was because that they didn't have problems with the kerosene vapor locking the fuel system like they did with gasoline on the earlier single fuel systems. Why do you think that they discontinued the "pressure retaining valve"? :-)



Edited 2 time(s). Last edit at 07/21/2009 07:56PM by SSsssteamer.

It is a pain in the butt to leave after a good lunch and discover as you pull out into traffic, that your fuel pump is vapor locked. It is a good practice to always close your fuel pressure retaining valve when the car is parked for any period of time. The condensing cars discontinued the fuel pressure retaining valve with the model 735. Probably because there wasn't as much of a problem with vapor lock while operating on straight kerosene in the condensing cars, as there was with straight gasoline on the pre '14 Stanleys. Kerosene fuel (two fuel) systems came out in 1914.

I think if you use it on a regular basis then you won't forget it. After I start rolling down the road I shut it off in the 725, which is 1916, I operate unless it's slow going. I don't own the car, but I drive it when I can. Once you get rolling the automatic fuel pump holds the pressure and the hand pump is not necessary at all after the firing up process in general.

Robert Hopkins

Dear Robert, The model 735 hand air valves to the fuel system are not to be confused with the non condensing Stanley fuel pressure retaining valve, as they are for different uses. On the noncondensing Stanleys, the fuel pressure retaining valve has to be in the open position while traveling, or all of your replacement fuel will be bypassed to the main fuel tank from where it came from. On the condensing Stanleys, the hand air valves to pressurize the fuel have to be turned off while under way to prevent from using up your air supply, and also to prevent fuel at 140 PSI from back filling into the air supply tank. SSsssteamer

Thank you for that bit of interesting information did not know that the non-condensers had a different arrangement for the pressure retaining valve.

Robert