Kawasaki Ninja 1000 Forum banner

Tank pressure purge

5K views 13 replies 8 participants last post by  rcannon409 
#1 ·
Have a 2018 ninja 1000, the issue I have is the tank when full will often bubble out fuel from the top of the fuel cap.

when I got it (new) I used to always notice walking by it would make a kind of pump sound occasionally. I have always assumed that the tank must be purging the internal tank fuel pressure. I have not noticed this sound since around the time this issue began.

I have checked the drain from the tank cap, it actually was not flowing freely thanks to the servicing mechanics that did not push the hose back down when they lifted the tank - this was a long time ago I fixed that issue creatively.

But the cap continues to flow out fuel when full. Some may be thinking I am over fuelling - but this never used to be a problem and I used to fill the tank more than I do now.
The fuel can bubble out while sitting (e.g on a warm day most likely), or while I am riding which is very annoying having fuel all over me. Likey because the tank warms up from the engine and expands the fuel.

I do believe this to be pressure related (the pressure of the fuel in the tank, not pressure between the cap). That pressure is high enough for the fuel to force its way straight up - thus coming out the top of the cap past the seals and not the drain in between.

The tank cap seals seem fine too.

Does anyone know if there is a fuel pressure release for the inside of the tank and if so how to locate it?

Thanks in advance.
 
See less See more
#3 ·
If you are at a point where liquid is flowing, from the cap, your final solution will be to put less fuel in it. I suspect it was being overfilled. When the fuel got hot, while overfilled, something had to give and it blew out the fuel caps gasket. Not so much the gasket, but the seal related to what's on the video.

When I get back home, I'll take a picture of the fuel neck on my California compliant tank. I'm not sure how well it will photograph, but it will give an idea of just how full they want these tanks to be. If I fill mine to the bottom of the neck, its "full", but the real level is probably 85% full.

I'm not sure where you are at, or if your bike has the vapour recovery system. I keep thinking you are in Australia. Forgive me if that's not true. My California bike had this vapor recovery box. The newer bikes might all have this as part of the upgraded emissions system? If it has this black box, I suspect it's a full of fuel, too. That's why you could get by with overfilling, before. It was all good until the vapour box filled with fuel.

Find out if your bike has this box, and well go from there. Its piece 16164 on the drawing. They dont even show an alternate drawing, anymore. My old 2012 had a drawing with this box, and one without.

 
#4 ·
If you fill it above this area, it's going to be a problem. It's tough because the tank will physically hold another 1/2 gallon, but you cant do it...well, you cant do it long term.
30921
 
#6 ·
Good pic but you also show why gas should never bubble out of the top of the tank. That hole under the Sharpie has a hose that leads to the ground in non-CA bikes and into the recovery cannister on CA bikes.

I always fill to the upper ring when on trips and don't have any drainage unless I fill and immediately let the bike sit. Then you get a few drops out the overflow hose. The only ramification this when I'm traveling is if I stop for gas and food or rest, do the food or rest first. Then gas and go. On my '18 the bike had the canister for about 2 weeks before it disappeared and that hose got routed to the ground. My '11 and '14 Ninjas were already routed to the ground. Bike services and even myself have kinked this hose, sealing it off. I usually just pop the tank lid and put the my air compressor against the hole and listen for air coming out the bottom of the hose. A kink is easily fixed by a gentle tug on the bottom of the hose.

What I've found when I fill to the upper ring is I need to ride 5-6 miles before parking the bike if I want to avoid overflow. I live about 1 mile from where I normally gas up and married a super sensitive gasoline smell detector so if even one drop of gas falls out of the bike parked in the garage I get a report. :) Why fill to the upper ring and add that extra half gallon of gas? It gives me a comfortable 200 mile range. With my riding style I have, I can get 200 miles out of the 5 gallons in the tank but it means spending the last 30+ miles or so watching the flashing low fuel warning. Adding that extra half gallon means not having to think about. What's magic about 200 miles? I suppose after 5 VFRs with 5.5 gallon tanks that gave me 200 mile ranges it's what I know and I'm too old to change.
 
#7 · (Edited)
The following comments do not address the problem that the OP has, but they may be of interest to some.

Like kenors, I use my N1K for touring, and like kenors I sometimes want the maximum fuel range, but there is a problem. The design of the N1K tank is such that an air pocket is formed when you fill the tank above the "base plate" as shown by RC's photo (see above) and this makes "over-filling" the tank for maximum range difficult.

There is an old BMW "quick & dirty" trick that removes this air pocket. I've done it, but this modification may result in significant damage to you fuel tank if the hammer slips, and even an explosion from fuel vapors. Proceed with caution and at your own risk.

1) Fill your tank full of petrol.
2) Take a large long drift/punch, with a very sharp point, and place the tip of the drift under the top lip of the filling neck, on the side opposite to the side stand. The drift needs to be about 6"~8" long. If you don't have a suitable drift, then sharpen one end of a long 3/8" bolt.
3) Hold the drift very tightly against the fuel filler neck so that it does not move.
4) Now, take a large heavy hammer and give the drift one good strong hit and punch a hole in the side of the filler neck.

You should end up with a hole about 1/8" in diameter and this hole will allow the air to vent as you "over-fill" the tank to the maximum capacity.
 
#8 ·
Thanks all - there is a lot then that needs to be looked at for my issue. I have been overfueling without understanding that was the case. Now I understand with rcannons pic, I was filling to the other side of the neck not the lower side. Thinking - well I only ride upright (most of the time 🤣).
I live 56km from work, 112km a day. working on 280km to a tank I fuel the bike twice a week. I don't want to run the tank dry so that 280km has to factor in leaving plenty in the tank. For now to avoid the problem I have to fuel up 3 times. I know that sounds "so what", but am in a similar position to kenors with the VFR range, bought this bike because on paper it should do the range comfortably. Filling up add and extra 10 minutes to an already 1 hour ride to work.

I will try cleaning the cap as per 57x helpful post first, never knew the cap was this complicated - always wondered why these big dep caps now days over the small ones of yester years.

I am in Australia.

The only thing I cannot be sure of is what this vapor box is that rcannon mentions, cannot locate something called that on the microfiche, is it this?
30931


Can the canister be cleaned of the fuel?

Thanks Murphyau for the idea around the air pocket, might only do this if the other solutions do not solve the issue.
 
#9 ·
Yes, you identified the canister.

The canister can be removed and thrown away. See the snakey line that runs up to the canister? Take the end off the canister and thread it down near the kickstand. You'll have plenty left over so trim to an appropriate length. This does mean that if you overfill the tank and it kicks out some gasoline it will just run out on the ground.

You can simply plug the other line running to the Purge valve (6). It's a vacuum line that runs to the #2 cylinder intake. I put a little rtv on a short bolt and "screwed" it into the end of the hose. You could go in and cap the spigot where it goes in but getting in there was more work than I wanted to do.

You can also simplify things by removing the purge valve itself but unless you put a load on the line that runs to it you'll get an error code. I simply added a 560 ohm resistor across the connector with some electrical tape to seal it off and called it good.

Once the canister gone there's a lot of space to mount something else, like a nice loud horn...

The only thing I cannot be sure of is what this vapor box is that rcannon mentions, cannot locate something called that on the microfiche, is it this?

Can the canister be cleaned of the fuel?

Thanks Murphyau for the idea around the air pocket, might only do this if the other solutions do not solve the issue.
 
  • Like
Reactions: Phil
#10 ·
I always sit on my bike when I fill it so it's level and I fill it to the bottom, and sometimes slightly above, the bottom of the filler neck where RCs marker is sitting. Never had an issue of any kind. I would've never imagined it could even cause a problem.
 
#13 ·
I do the same all the time except I don’t sit in the bike. I overfill it becasue I know when the bike is in the side stand there is a lot of room in the tank on the “high side”, and have never had a problem either. As Kenors said, it’s about range. I often ride where its a long way between gas stations and I like as much range as I can get.
 
#11 ·
Cleaned the cap insides - but already seemed clean as a whistle. There was a little filter inside and it was clean too. So not sure if it is going to make a difference. I also now understand why filling up higher than the recommended would cause a problem like this. I put a clean tool down the pressure equalizing hole while the cap was removed (cant really do this with any sizable tool while the cap on as the grommet is in the way). Was able to tell that the metal tube for that breather hole goes down to the same level as the recommended fill level in the tank - thus overfilling will not allow pressure to equalise.

Couple of notes for anyone who reads this and wants to clean their fuel cap:
Watch the grommet for the pressure equalizing hole as you remove the cap from the tank. It is not fixed in position (just held there via the cap being screwed down), I imagine would be really easy to drop that inside the tank!

When you pull apart the cap and unscrew/remove the lock mech, the black plastic bits DO come out but you have to flip the cap over (which you will do anyway to unscrew the rest of the cap. BUT all the plastic bits, spring and tiny filter will fall out. I lost the filter for a while 😒. It is tiny, white and flat.

Going to remove the canister next, but if that does not work - the only way I think to avoid fuel spill (if I am going to over fuel still) would be Murhyau suggestion.
 
#14 ·
Remember , our original person isnt asking about theory, or extended range.. His tank IS letting fuel out past the cap. It's happening. Just like that tv show my wife watches "This is Happening".

With that in mind, is there a fix that will let him continue to fill the tank this high? Removing the canister is smart. I suspect its "ruined". I put that in quotes because it's real value isnt much, anyway. It was never designed to see liquid. You cant open it up to let it dry. Well, you can....once.



 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top