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Discussion Starter · #1 · (Edited)
I originally posted this on a VLX FB page and received one response that was pretty vague. So I am bringing it here to the blog in hopes that I can get more feedback.

Fuel system issues: 2005 VLX 600, VT600CD.
Original Carburetor.
Removed Velocity Stack and installed an aftermarket foam filter.
rebuilt carb with OEM parts.

Hi all,
I’ve been having some strange issues and thought I’d share and hopefully receive some responses.
I’ll apologize in advance if I seem long-winded talking about this.

A couple of weeks back we experienced an issue with the fuel continually flowing into the carburetor overfilling the bowl and filling the cylinders and exhaust with fuel.

Very little fuel came out from the overflow tube. Approximately 1/2 a tank went into the cylinders and exhaust system.

We also discovered that we had forgotten to turn off the petcock. I might mention that the “Auto Fuel Shutoff” had been removed prior to this issue.
We were following the recommendation of removing it because they instructed that it was not necessary.

So we installed a NEW needle as well as brought the carburetor back to OEM specifications. I purchased a rebuild kit from Honda. I also purchased a NEW accelerator pump because this one was not squirting as it should.
Anyway, we removed all of the excess fuel and rebuilt the carburetor.
It ran great last weekend.

Yesterday we smelled gasoline fumes again as we did the last time.
We tipped the bike over on the intake side of the intake and fuel poured out once again as it did before.
We verified that the petcock had in fact been turned off.
So we repeated our process of removing the fuel once again.

But this time we had a hiccup and had a little flame out so to speak. This didn’t happen the last time. But we then realized that the secondary spark plugs were still connected which ignited the fuel within the cylinders.
We checked the float and it appeared to be ok. The needle had no damage as well.
We did locate the “Automatic Fuel Shut Off” and reinstalled it.
So far we’ve static tested it and all seems fine.
The Auto Shut off seems to be working correctly.
The petcock is shutting off also.
Let me know if you’ve experienced anything like this and what you did to remedy it.
Let me know your thoughts on the Auto Shut Off valve if it’s necessary or not.

10 Posts
Discussion Starter · #5 ·
If the fuel pump is OEM, I would focus on the float(s), since it sounds like they’re not properly stopping gas flow into the bowls.
Troy, I agree with you.
I did test the floats today. I submerged them in water for around an hour. When I remove the item that was holding them down they popped up to the surface. So I'd say they are good and don't have a pinhole in them.
I wish the floats were still brass. (pictured) They were so easy to adjust the needle and seat as long as they didn't have a pinhole in them.
So now I'm steering towards the needle and seat itself. The needle is NEW. But the seat may be washed out. When I get home I'll have to see if the OEM rebuild kit has a seat. I don't believe it did.

Backing up when we got the bike. The petcock lever was missing so we could not shut off the fuel when the engine was off. So I replaced it with a new one.

Also, Thank you for explaining why they have the Auto Shut off valve. I hope this one is working properly and dosen't have an internal pinhole allowing fuel to go through the vacuum line into the crankcase. That would be a bummer.
We kept thinking that maybe Honda put it on because there was a design flaw in the fuel delivery system. I.e. the petcock. We ain't too bright at times. LOL

Thanks again for your input.


10 Posts
Discussion Starter · #7 ·
It's doing this while sitting? If so, I'd check/recheck the float bowl vent hose and tank vent hose for obstructions. They can run fine, you stop, heat soak sets in, the fuel vapors have no where to go, so they push fuel out into the venturi, where it runs down into the cylinders... just sitting in the sun can also do this. As well as the tank vent being blocked

Edit: also had them do it while running, might pull up to a stop, it dies and you smell gas as it's flooded.
Float vent hose aka overflow hose: I tested it and it's clear. All ports on the carburetor are clear. Tank Vent hose: There is NO tank vent hose. There's a vent hole on the inside of the cap. It's supposed to vent through the tank cap. I sprayed a lot of carburetor cleaner into the gas cap thinking that (as mentioned) the gasoline is creating pressure within the tank causing it to force fuel through the CLOSED petcock and flooding into the cylinders. To me, if the gas cap is vented correctly the atmospheric pressure should stabilize and not cause the fuel to come out of the petcock when OFF. But will flow freely when the petcock is ON. I tested it by opening the petcock with the cap on the tank. The fuel began to come out normally but as it progressed it began to trickle. So I removed the gas cap then the fuel began to flow normally once again. I've also replaced the petcock with an aftermarket one and it still leaks in the OFF position. I'm so frustrated. My son says that maybe that's why they had the AUTO SHUT OFF valve on them. Maybe HONDA realized that this tank design had flaws and they corrected the issue by installing the AUTO SHUT OFF valve. I believe I mentioned that the AUTO SHUT OFF has been removed. This isn't rocket science it's a simple opening or closing of a valve and fluid flows or stops like a faucet. UGH!

10 Posts
Discussion Starter · #11 ·
I'm having trouble believing they don't have a vent other than the cap. If it's vented. It has been superceded


17620-KR3-013 replaced by 17620-KR3-023

fits models all the way back to 1985 look under the right rear edge of the tank for a vent hose?
Ok if I am reading this correctly HONDA replaced the OEM cap with the 17620-KR3-023? Also, to respond to the VENT hose under the tank. No there is NO vent hose under the tank. Just the Petcock.
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