fuel leaking into airbox

Everything in-between the gas cap and the carbs. Also how the engine inhales.
devil1
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Joined: Thu Feb 12, 2015 2:02 pm
I ride: 93 en500 kawasaki

fuel leaking into airbox

Postby devil1 » Thu Feb 12, 2015 2:22 pm

fuel leaking into airbox im new to this so here goes we turn the fuel on run the bike en500 stop the bike fuel really leaking from airbox any ideas on how to fix the problem thanks very much

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Triangles
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I ride: '94 Black Cherry Vulcan 500, '06 Candyfire Red Vulcan 500 LTD
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Re: fuel leaking into airbox

Postby Triangles » Mon Feb 16, 2015 8:43 am

Do you have an EN500A or EN500C (what year is it if you don't know what I am talking about)? Either your float has sprung a leak or your float needle valve needs to be replaced or both. A quick google search brought up this on bike bandit so you know what the part looks like. I would recommend the K&L float needle over the oem part. If you can even order an OEM replacement it will be more expensive and is no better than the K&L part. If you don't already have a shop manual I'd recommend getting one. It's a fairly simple procedure to fix this.

Additionally these bikes have a vacuum actuated fuel shutoff valve which should prevent fuel from flowing out of the gas tank when the engine is not running. If gas continues to flow with the engine off and your fuel valve is in the ON or RES position, you should consider rebuilding your fuel shut off valve as well. K&L also makes a rebuild kit for this so you don't have to buy a whole new valve. You can only get a whole new valve from Kawasaki since they don't sell parts of the valve.
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dmsmith
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Joined: Mon Jul 03, 2017 8:20 am
I ride: 2000 Vulcan 500 LTD
Location: Palmyra, NE

Re: fuel leaking into airbox

Postby dmsmith » Mon Aug 13, 2018 7:28 am

I took my year 2000 on a 1,000 mile road trip last weekend. Got back Tuesday night. Rode to work Wednesday. No problems. Got on Thursday morning to go to work and wouldn't start. Gas started coming out the air chamber behind the carbs. If there's a leak or needle problem wouldn't it run on the other cylinder? Seems weird that both would go out at the same time.

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Triangles
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Re: fuel leaking into airbox

Postby Triangles » Tue Aug 14, 2018 3:37 pm

There could be a number of problems here. I'll start off with your fuel petcock for safety reasons since we don't want you or your bike to go up in flames.

Fuel Petcock:

The fuel petcock has a little rubber diaphragm that engine vacuum causes the diaphragm to open fuel flow down to the carbs. As noted above if gas is flowing but the engine is not running you should start by fixing the fuel petcock valve. I would think the vacuum valve would fail shut but I'm not very familiar with the failure modes of these fuel petcocks. If you pay attention to how things are put together when you take the valve apart it should be fairly self explanatory of how to re-assemble with the new K&L kit parts. Note: one kit often does several valves so it may have parts you don't use so don't freak out when you see parts that don't make any sense. I vaguely remember testing the last one I rebuilt years ago before I put the gas tank back on the bike by putting some extra hose I had laying around on the vacuum port and sucking on it to open the fuel flow. Not sure if this would work on the EN500 and also there's a risk of getting a mouthful of gasoline if things aren't right so you have been warned if you try this test before putting things back together. Once you have the fuel valve operating correctly then move on to the carbs.

On to the carburetors:
To answer your question "wouldn't it run on the other cylinder?", That is entirely possible that it would. It's been several years (knock on wood) since I've had to fiddle with carbs so I'm going from my fuzzy memory and may not be correct. My best guess as to why it wouldn't run on the other cylinder is that I believe the two carbs fuel bowl vents are connected and when a float bowl overflows fuel can also overflow into the other float bowl, down into the engine, and out the airbox (basically it goes everywhere). It's also possible that liquid fuel going into the one cylinder caused too much resistance to the engine turning over. Sort of like a partial hydrolock.

If you're impatient, believe the fuel petcock is functioning properly, or just want to continue troubleshooting while waiting on parts to come in, at a minimum you should establish the following:
1) Fuel does not flow from the gas tank when the fuel petcock is in the "ON' or "RES" positions (obviously while engine is not running).
2) Switch the fuel petcock to "PRI" (Prime) and verify fuel flows.
Basically you want to verify that you can stop the fuel from flowing out of the gas tank so you don't inadvertently make a fireball/mushroom cloud.

I could have sworn it's been discussed on this forum but I don't see anything after a quick look. I highly recommend swapping the diaphragm cover (top of carb) and float bowl (bottom of carb) screws with socket head cap screws or hex head cap screws so that you can more easily service the carbs in the future by using a socket/wrench or allen key to remove these screws instead of the easily stripped phillips head screws. Heaven help you if you strip one of these phillips screw heads. As an additional PSA I'll note that these screws tighten with even the slightest corrosion between the screws and aluminum/pot metal of the carbs housing. I use never-seez and they still tighten up after a while. The cast aluminum/pot metal is very soft so you don't want to crank the screws very tight and risk stripping the threads. Just make them snug or better yet follow the torque specs in the service manual when you put things back together. For what we're doing here we can leave the diaphragm cover alone as we have no need to do anything there and there is a spring under it that will want to leap out anyway. We should be able to do everything without having to remove the carbs from the bike as we'll only be removing the float bowls.

One of two things has likely happened:
1) The float has sprung a leak and is no longer floating up to stop the fuel flow (least likely).
2) The float needle is not sealing (most likely).

To check for scenario 1 you can simply remove the float bowl and see if there is fuel inside the float. I believe the float is plastic so it should be easy to tell. If it's metal, that makes it a little harder to check since you can't see inside the float. You'd have to remove it and shake it or be able to visually see a hole in it. If you can use a bit of tube and use the drain screw on the float bowl to empty the gasoline in it before removing the float bowl. Also it is recommended to replace the oring gasket when you remove the float bowl as the old one may not seal when you put it back together. If the float is ok then scenario 2 must be the case. Even if you find a bad float the float needle is cheap enough you might as well replace it too while you have everything apart.

For scenario 2, IIRC the float needle basically has a rubber cone tip that presses against a brass seat that is the fuel inlet. Before replacing the float needle use a q-tip or something similar to clean the fuel inlet where the rubber tip seats against to ensure you will have a good seal to stop fuel flow. If it's heavily corroded it may need more attention. In theory you are supposed to check and adjust the fuel level in the float bowl by tweaking the tab where the float needle attaches to the float. The last time I did this I just checked the fuel level in the float bowl and it was pretty darn close just putting things back together so I left it as is. Note: you will need a helper here as the bike has to be straight up (not on the side stand).

As a final note before getting back on the road you really should do an oil change. It is highly likely fuel has gotten into your oil. Even if the oil level looks right in the sight glass. The fuel dilutes the oil and causes it not to be able to lubricate as it should. So this is just cheap insurance if your oil level looks proper and a must if your oil level is higher than it should be.

Hope this helps...
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dmsmith
Posts: 8
Joined: Mon Jul 03, 2017 8:20 am
I ride: 2000 Vulcan 500 LTD
Location: Palmyra, NE

Re: fuel leaking into airbox

Postby dmsmith » Wed Aug 15, 2018 7:15 am

thanks for all the advice. I appreciate you taking the time to write all this out. Things are a little busy right now so not sure when I'll get to work on it. (fortunately I have a backup bike) But I'll let you know how things turn out. Thanks again, for both the advice here and the forum in general.


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