vacuum line from intake/carb

[Milemaker13]

hose barb on fuel pump

I have a hose barb on the bottom of my fuel pump, but no hose attached. I don't know what this connection is. The engine runs like this.
I was thinking it may be a vent? If it is a vent, should it be routed out of the hull?
This is the 165 hp straight six.
I have a picture, but am having trouble uploading it. TrYing to figure that out.

 

[Milemaker13]

Another thing I noticed on my 165 hp straight six is a vacuum line hanging from the carb intake, not connected to anything. . I think this used to connect to the distributor for the vacuum advance. My distributor has a wire that is connected to one of the primary terminals of the ignition coil. I assume the guts in the distributor have been updated.
Should I plug this open vac line?

 

[thumpar]

There is no vacuum advance on boats. They use weights. It sounds like someone put an auto carb on it.

 

[Grub54891]

Are you sure it's a vacuume line? A pic would be good. Does it come from the carb body or the air cleaner/spark arrester?
If from the arrester,it should go to the valve cover. If from the carb body,you have an automotive carb,therefore,it has no place on a boat.

 

[Grub54891]

That barb should have a clear hose coming off it and routed to a similar fitting on the carb. It's to tell you that the pump is bad. The line will get fuel in it when the diaphram starts to leak. On a car the fuel just drips on the ground. On a boat,well gas ,fumes, and sparks collect in the bilge,,,,kaboom! I'd highly suggest to replace the line.soon.

 

[GA_Boater]

I merged your two threads about the vacuum hose and barb on your fuel pump. The fuel pump barb is not a vent, it is a safety feature in case the diaphragm ruptures that prevents fuel being dumped into the bilge creating a fire hazard. The other end of the hose goes to the carb to keep it out of the bilge.

If your distributor has vacuum advance, your need to replace it with a marine unit. As stated, advance is solely done with weights, not vacuum. A non-marine distributor is a fire hazard because it has no shielding to prevent fuel fumes from getting inside and going boom.

 

[Milemaker13]

Thanks for the info. I think I have all correct marine parts , but I am familiar with automotive so I may have mixed things up.
Ok, so the tube from the carb is a safety to suck fuel in case of diaphragm rupture. Check. I will run that tube to the fuel pump. I assume the engine stumbles or dies if that happens.

 

[achris]

Thanks for the info. I think I have all correct marine parts , but I am familiar with automotive so I may have mixed things up.
Ok, so the tube from the carb is a safety to suck fuel in case of diaphragm rupture. Check. I will run that tube to the fuel pump. I assume the engine stumbles or dies if that happens.

Right and wrong. If the diaphram ruptures the pump pushes fuel into the carb at a uncontrolled rate, stalling the engine by flooding, thus stopping the fuel pump. The carb doesn't suck it in.

Also, there seems to be a bit of a misunderstanding on marine and auto distributors. Correct in that marine don't have vacuum advance diaphrams and they have weight for a centrifugal advance. But auto distributors also have weights. The vacuum advance port on the carb for the distributor is part way down the throttle barrel, and doesn't have enough vacuum to pull the advance in until the throttle is backed off ('cruise' mode). As they is no 'cruise' in a boat, even if there was a vac advance unit on the distributor it would never be pulled in. We don't use auto dissy on boat not because of the vac advance unit, but because auto dissys don't have the safety features required in a marine distributor.

Chris....