Purge Valve what do it do?

[hughjorgan]

New to me boat, trying to clean up the engines.
So working on my port engine (2008 DF300) noticed a rusty part that pretty much crumbled when I tried to examine it.

Shows a purge valve in the service manual. Ordered a replacement and installed it, then thought I best check the starboard one. Yep, same condition. Replaced that one.

Now, since these motors have run very well since I got them (18 months or so) and these valves were obviously not functioning.

What do they do?

[Harper]

I can only guess......it attaches to a line coming off the top of the VST. My guess is that it's an emissions gizmo to close the vent and block fumes from the VST when the engine is off. Can't tell where it purges the vapor to when open. Probably not critical to engine operation, as your experience bears out. My DF150 doesn't have it...the vent line is open to atmosphere.

[hughjorgan]

Thanks, a little more research shows you are correct. This one goes into a charcoal canister.

[Harper]

Thanks for the info. Though it seems a little useless, since the fuel tank on every boat that I know of is open to the atmosphere, unlike modern cars.