Fuel Pump Vent

My newly purchased fuel pump has a small diameter vent tube protruding from the top (above the diaphram). I assume this is so a hose can be connected to expel gasoline to a safe area when the pump ruptures. Is this tube normally left open (un-connected to anything) or is a venting hose normally ran somewhere? If so, where?

Thanks David. My new spark arrestor did come with two nipple looking things that have mounting tabs attached, shipped loose in the box. The only problem is the nipples are sized for what looks like 5/8" or 1/2" hose (perhaps for a PVC valve hose). So now what? Use a reducer of some sort? (They just don't ship these things with instructions and when you are upgrading from older equipment you have nothing to look at.) Thanks for your help.

Scary. I assume the clear vinyl hose can be tie-wrapped to the fuel line.

Jim:

Do not put the nipple on the bottom...the fuel will pool on the bottom of the arrestor and leak onto the manifold. Spark arrestors can be purchased with the correct sized nipple. I purchased my arrestor from CC and it has both the fuel pump nipple and crankcase vent nipple.

If the fuel pump starts weeping, you want the fuel to be ingested via the carburetor, so the nipple should be at the top side of the arrestor. The nipples are attached via a tap and do not actually penetrate any part of the spark arrestor so as to allow a backfire flame to ignite the fuel in the hole.

My Holley 4160 4V Marine carb has a small hose bib protruding from the neck of the carb. That hose bib is the exact same size as the hose bib on the fuel pump. The carb came from the factory with a rubber cap installed on that hose bib. Could that hose bib be intended for the vent hose from the fuel pump?

Jim:

First question: No the arrestors have the nipple on the outside that are held to the top of the arrestor with a metal tab. Nothing penetrates the arrestor.

Second question: Any nipple that will introduce the fuel into the carburetor (above the throttle plate and venturies should work fine. Since the nipple is there, use it...my carb does not have one. But, then again, I am using a automotive carb modified to be marine safe.

using an automotive carb modified to be MARINESAFE .are you serious ?

the main ingredient for a coast guard legal marine carb is in the throttle shafts and throttle plates.
the shafts are grooved and slabbed to channel the flooded fuel down the intake.and the plate bodys have a special seal.
feasible yes. practical hell no.it would be cheaper to buy a new one.

just one more point for everybody.
never use a gasket between the carburetor air horn flange and the flame arrestor.it's possible this gasket could become saturated with fuel if the carb should flood.
some things we learn the hard way,but never ever forget..

i'v spent my weekends for many years pumping fuel,[and selling worms ]at the marina.we have fire exttinguisher's everywhere.i don't ever want to have to scramble to get one again. for any reason. point made !