Why is this line plugged on my fuel pump?

[Punisher]

Can anyone help me out?I just bought a 1979 18' Witchcraft with a 454..We are getting ready to fire her up tomorrow but noticed that the previous owner plugged one of the lines on the fuel pump...It looks like a 1/4inch hose coming out of the fuel pump.Is it a vaccuum line?I will try to take a picture of the hose..All and any info will be greatly appreciated

[Squirtin Thunder]

That line is a vapor line. It is part of the US Coast Guard marine required equiptmen on closed engines. This line would normally go to the spark arestor.
Is there a spark arrestor on the engine ???

[Punisher]

no spark arrestor on the engine...It has panther headers that go out the back and isnt a closed engine..Does it have to be hooked up for the boat to run?
EDIT:Is the spark arrestor part of the intake system or exhaust system?

[Squirtin Thunder]

no spark arrestor on the engine...It has panther headers that go out the back and isnt a closed engine..Does it have to be hooked up for the boat to run?
EDIT:Is the spark arrestor part of the intake system or exhaust system?
It is part of the USCG Marine equiptment requirements, like paddle and fire extinguisher.
No it doesn't need to be hooked up to work. I would replace the fuel pump with a real good pump that doesn't need a regulator.

[kp216]

The flame arrestor is the "air cleaner". It should be stainless or aluminum screen, or one of the K&N USCG approved flame arrestors.
This is one from Rex that has the tube for connecting the fitting you're asking about.
http://shopping.rexmar.com/Merchant2/graphics/00000001/125101.jpg

[Punisher]

thanks for the info...looks like i gotta wait till monday to pick one up

[Zeug]

One note of caution- My boat came with a fuel pump that was for a car application not marine and had a third line coming out of the top. I doubt it is a marine vent tube but rather some sort of pressure bypass. I know the fuel pump isnt a marine app because Autozone caries the same one for a car.
I am affraid that if you just dump it into the carb you might have some problems. Also, I took the cap off of the thrid tube on mine and the pressure dropped down to where the boat didnt run good. So mine stays plugged.
If your going to run it into the carb check first. I would run it with a hose attached to a catch can and see if the motor still runs right and if you are dumping large amounts of fuel into the can.
Kent

[steelcomp]

It is part of the USCG Marine equiptment requirements, like paddle and fire extinguisher.
No it doesn't need to be hooked up to work. I would replace the fuel pump with a real good pump that doesn't need a regulator.
That's rediculous. There's NO reason to replace a perfectly good pump if it's working. Leave the port plugged. If your engine isn't enclosed, you don't necessarily need to run a flame arrestor (not spark arrestor), either. An air cleaner wouldn't hurt.
That tube is there to purge any fuel vapors from your fuel pump back up to the carb instead of settleing in the bottom of an enclosed engine compartment. It has no effect on how the fuel pump is working. Enclosed engine compartments and gas fumes= boat bomb. A flame arrestor is there incase of a backfire where flamaes from the carb might ignite some of those fumes in an enclosed compartment. With an open engine compartment, it's not a concern. :coffeycup

[SmokinLowriderSS]

The fuel pump line is actually where the WEEP HOLE on a normal automotive fuel pump would be. On a car, if the diaphram cracked or leaked, fuel leaks out the hole and onto the ground. A hose has to be connected to this in a covered engine and (IMO) should be connected to either the flame arrestor cap or (in some marine carbs I have seen) to a small tube piece that passes through the flange next to the air horn and arches over to dump in a venturi. That way, if the fuel pump starts to leak, it pumps the leakage into the carb, safely.

[steelcomp]

The fuel pump line is actually where the WEEP HOLE on a normal automotive fuel pump would be. On a car, if the diaphram cracked or leaked, fuel leaks out the hole and onto the ground. A hose has to be connected to this in a covered engine and (IMO) should be connected to either the flame arrestor cap or (in some marine carbs I have seen) to a small tube piece that passes through the flange next to the air horn and arches over to dump in a venturi. That way, if the fuel pump starts to leak, it pumps the leakage into the carb, safely.
Hey SS...I always thought that too, but what keeps the fuel from just running into the crank case? It's a long way up to the carb through that little tube, and there's no pressure forcing it up there. That side of the fuel pump is open to the crank case through the mounting flange, where the pump arm is. Carb airflow would pull fumes, but not liquid fuel...too heavy.

[SmokinLowriderSS]

The pump chamber is likely sealed on the inside block area steelcomp. That would protect it (isolate it some) from engine oil, heat, pressures/vaccumes. I don't think there is a way for the fuel to go to the oil pan. Besides, it would make no sense for the entire system if that were possible. You would also never know you have a problem if it dumped 3 or 4 gallons of gas into your crankcase, till tyour engine grenaded from poor lubrication. At least pumping it into the carb throats causes it to enrich, getting your attention hopefully while burning it off safely.

[SmokinLowriderSS]

The orriginal hose on my 454 had a long thin strip of paper in it that read "If liquid is seen in this line, replace fuel pump".

[steelcomp]

Cool. If the pump is sealed to the crankcase, that makes sense. Don't think I've ever seen one like that. Most I've seen are open...in fact you can tell when they go out, 'cause all of a sudden you have more oil than you're supposed to!
Thanks :D

[SmokinLowriderSS]

I could be mistaken steel, I haven't looked that closely at any fuel pumps on my boat. (replaced mine in early '03 .... $180) I just don't THINK they'd drain into the crankcase like that by design. That'd be so friggin' hard on oil and all those other expensive parts by proxy. I'll have to look closely if I ever have 1 off again. :idea: