Where does the red hose go? - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 16 (permalink) Old 02-18-2016, 05:41 PM Thread Starter
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Where does the red hose go?

. . . so i was finally able to pull the battery cage, disconnect all of the connectors without breaking too many tabs. Sanded all the crud and rust off, and only had to use a drill on one of the R/R bolts. And while the paint was drying on the cage today i figured i would route my rear brake cable "correctly" behind the radiator reservoir instead of the route up against the engine block where my favorite genius mechanic had shoved it, but that's another long story. After pulling the reservoir, though, poking around and checking things out, i found a hose with a tiny clamp on the end just dangling like an overflow of some kind. . .

Following it back to its other end, it's connected to the fuel tank along with another; each with its own color coded "dot". The blue connects to the top of a small fuel pump. Another hose from the top of that pump goes to the "canister". Checking the little fuel routing diagram on the rear fender shows this "red"
hose supposed to be connected to the "side" of that little fuel pump. The pump on the bike only has three places to attach a hose, though. So now i am stumped trying to figure out where does red hose go?

And the little whisper in the back of my head reminds me that my engine is ( according to several people ) running "lean" and that's why it's backfiring on deceleration.

Do i need to get a "correct" part for this "return pump"? Was this a mod? Should it just dangle? Is there a nipple on the pump i must of missed?

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post #2 of 16 (permalink) Old 02-18-2016, 07:00 PM
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ok, this "pump", does it have 2 large hoses and a small one (or nipples for them?). if so, thats the valve for the emissions junk that gets removed with the ear shave, along with the hoses. ear shave procedure will usually stop the lean pop on deceleration.. what they do with that emissions junk is to let fresh air into the exhaust system (right at the exhaust vavle), on high vacuum conditions (decelerating), to facilitate burning of unburned fuel that gets into the exhaust system. thats the pop that you hear. the valve that runs this mess gets its vacuum signal from the right (rear cylinder) carb, and gets capped off during the ear shave.

the rear end (bottom) of the fuel tank, does it have 1 or 2 nipples.. single nipple is federal emissions (and canada), 2 nipples is california emissions.

the bike does NOT have a fuel pump, the entire system is gravity fed. the petcock is vacuum operated, getting its vacuum from the left (front cylinder) carb.

now, as far as the color coding goes, I cant really help you there. all of my hoses are just plain black.

One of the hoses at the rear of the tank (if you have 2, or the only hose if you only have 1) does vent to air, down below and behind the engine. its the tank's vent system.

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post #3 of 16 (permalink) Old 02-18-2016, 07:41 PM Thread Starter
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Originally Posted by michiganteddybear View Post
ok, this "pump", does it have 2 large hoses and a small one (or nipples for them?). .
Ok, so i am including some photos, but ifn i comprehend correctly, the red hose should be simply dangling like an overflow and it's a vent to the top of the fuel tank.

Also, ifn i am comprehending correctly, the blue hose can simply be plugged off at the fuel tank end, remove the hose and i need to read up on at least part of the ear shave enough to figure out what to do with the canister.

First photo is the "California" gas tank. Red hose is on the right.
Second photo shows what happens if one holds the red hose over the bike. See the fumes? Thought so.

Third photo is the "return pump". That's what it's called on the diagram on the bumper. Put your left ear on your left shoulder to see the top of the photo is the right side of the bike. Plastic on top is the reserve tank. Cable leading off to the right is the brake cable. Hose leading off to the left is the radiator reservoir hose ( from the bottom of the reservoir ). That "thing" with the rubber belt clamp around it is the "return pump" ( our new culprit ). Below that is the "Canister". Question... is this canister only on California bikes as well?

I have a funny feeling we are going to soon get back to the original meaning of "ripped off".

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post #4 of 16 (permalink) Old 02-18-2016, 11:32 PM
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I'm gonna guess the return pump is for vapor recovery from the charcoal canister back to the tank.

The small hose with the clamp may be part of the canister system. None of mine in that area were that small. had one that size for the drain off the bottom of the airbox, toward the front, think it ran down the side of the radiator.

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post #5 of 16 (permalink) Old 02-19-2016, 01:02 AM Thread Starter
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Originally Posted by Spockster View Post
I'm gonna guess the return pump is for vapor recovery from the charcoal canister back to the tank.

The small hose with the clamp may be part of the canister system. None of mine in that area were that small. had one that size for the drain off the bottom of the airbox, toward the front, think it ran down the side of the radiator.
What bothers me is that it *DOES* have a clamp on one end. I'll take a picture of the "fuel routing" diagram on the fender tomorrow morning when it's light out.

I just made a series of photos on rebuilding my battery cage. I am photo documenting everything to the smallest detail so that even a 6th grade kid could rebuild my bike. So that goes back in tomorrow, and if that charcoal box and etc, are just excess, erm... crap... now would be a great time to know it. The overall gist of that diagram though, is that the "red hose" hooks into that pump on the side... the canister is fed from the pump and has another outgoing hose to the carb "some place".

It only makes sense that adjusting the carb for popping, or blocking the reeds, etc... should be done AFTER removing this circuit. Do i comprehend correctly that this charcoal canister is only on the California bikes?
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post #6 of 16 (permalink) Old 02-19-2016, 02:03 AM
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Here is a pretty good diagram. It sure looks like that hose should go right to the center of the separator.It seems a bit long though.
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post #7 of 16 (permalink) Old 02-19-2016, 03:21 AM Thread Starter
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Here is a pretty good diagram. It sure looks like that hose should go right to the center of the separator.It seems a bit long though.
That's a much better diagram than what's on the fender ( which is just a 2D logic diagram ). Thanks for that. I am guessing the other nipple must be under the back of the retaining belt and i missed it during my inspection somehow. Tomorrow i'll take the reservoir back off again and get serious with it.

If the entire thing can be removed ( and it appears to be a mystery right now ) defeating it will be easy. Just blocking the blue hose from the fuel tank, and blocking the hose to the carb, starting up the bike ( if it will ) for a test, etc.

The only dread i have about that test is the location of the canister, and the return pump. It will mean removing the entire battery cage and putting it back in again, if i want to remove those parts ( and i will ).
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post #8 of 16 (permalink) Old 02-19-2016, 07:03 AM
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Do i comprehend correctly that this charcoal canister is only on the California bikes?
Correct. ... Warning: The Surgeon General has determined those canisters can cause tooth and hair loss, and have been connected with microcephaly between the right and left lower extremities.

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post #9 of 16 (permalink) Old 02-19-2016, 07:18 AM
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While i have her opened up, i may as well pull the canister/emissions pump *IF* that is possible. Just want to confirm the one tank hose should be left as a vent with a free open air end.
That is correct. Remove superfluous parts, leave one hose for the gas tank vent to open air.

Doing coasters or marbling/capping will lose a lot of the hose spaghetti too.

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post #10 of 16 (permalink) Old 02-19-2016, 07:59 AM
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The left nipple (blue hose) at the base of the tank is the vent line (from the fuel tank opening near the gas cap hinge) that should be routed to underneath the bike and left open. The right nipple (red hose) on the base of the tank is for the California emissions "recovery" system. I believe if you remove all that stuff, you could either cap it off, or vent it like the other hose.

Correct me if I am wrong, but if the right nipple (red hose) were capped off, the possibility of "sloshing gas" in a full tank could cause fuel to get into that line and possible get stuck in the line if you cap it off at the base of the tank.

I am not sure if it is better to cap it or let any fuel that gets to that line drain out the bottom of the bike through a hose like on the left vent nipple. I am sure the line is high enough in the tank (near the gas cap) that it should not act like a siphon oncee fuel gets to the line that is internal to the tank.
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