Gasoline Vapor

[Mo]

I have one on the Prt side leaving the tank and one near the filter. Will attach a few pics later.

[Jlmatt]

This is a quote from an article by Gordon Groene about the Atomic 4 published in 1976 in Motor Boating & Sailing. It was reprinted by Practical Sailor in May 1981.
"... Fuel should never be turned off to an engine-driven, diaphragm-type pump unless the shut-off valve is between the pump and the carburetor, because any interruption in flow on the suction side causes distortion of the diaphragm,--the major cause of diaphragm leakage"

[jpian0923]

Good advice.

[tartansailboat]

does this advice apply to an electrical pump, or only mechanical pumps??

[hanleyclifford]

This is a quote from an article by Gordon Groene about the Atomic 4 published in 1976 in Motor Boating & Sailing. It was reprinted by Practical Sailor in May 1981.
"... Fuel should never be turned off to an engine-driven, diaphragm-type pump unless the shut-off valve is between the pump and the carburetor, because any interruption in flow on the suction side causes distortion of the diaphragm,--the major cause of diaphragm leakage"

This raises some intereting questions and issues. It would seems that Mr. Groene is concerned about running a diaphragm pump dry and distorting the diaphragm. Point taken, but consider this: if the fuel is shut off downstream of the pump and hence the pump left charged with fuel and open to the tank, what is the risk if the diaphragm has a leak?Now the potential exists to empty a fuel tank into the crankcase! IMO the solution is to shut off the fuel upstream of the pump, but do not run the carb dry as a routine procedure at shutdown.

.

[jpian0923]

I guess the real question is, how long are you shutting the system down for? If it's only short term, I think shut down just before the carb is good. If long term, I don't know. Maybe at the tank outlet? Might have to prime the system and check your lines for integrity if that's the case.

[Loki9]

My P30 has an electric shut-off (solenoid valve) right on the tank, upstream of the mechanical pump. When the ignition is off, the valve is closed. I'm pretty sure it's original factory equipment. There is also a manual valve in between the tank and the filter (still upstream of the pump).

[smosher]

I have a P30 and I have a manual petcock, before the filter

Steve

[edwardc]

...The fuel level in a full tank on a Catalina 30 is a little higher than the carburetor and my float valve had a speck of debris allowing a slow siphon. ...

In my Pearson 323, most of the volume of the fuel tank is above the level of the carb. The boat came with a Fuel/Trol electric cutoff valve mounted at the tank. It is wired to the ignition circuit, so as soon as I turn it off, the fuel supply is cut off. This seems like a pretty good solution, as I don't need to remember to do anything extra when securing the boat.