I am completely stumped.

[Parminio]

Just did a lot of stuff to my 2007 Vmax and it's running better than ever. I've only been going on short trips around the house to seat the new brakes in before I do anything else. The other day, I suddenly had a very strong smell of gas. I figured it might have been because I was running some Seafoam through it as it's been sitting since November of last year and maybe that was it.

So I didn't really think that much of it.

So I took it out yesterday for a short 40 mile run and I didn't smell nearly the gas smell that I had before. I figured everything was cool. Again, bike's running and handling better than ever.

So this morning, I go out to the garage to put an empty milk jug in the recycle bin and I'm just FLOORED by the smell of raw gas the instant I open the door. I look down and see this spot under my bike:



Full disclosure: The bike had been moved before I took that picture. It was right under the middle of the bike.

So I start doing some investigating and notice that my number 1 carb boots are wet with fuel. I figured, "AHA! Probably a stuck float!" so I pulled the carbs. This is what I saw:



Now what gets me here is how much dirt, not just gas, is on that number one boot. That tells me that carb probably wasn't seated so it was sucking in a bit of dirt. If it were leaking out, there would be no dirt there.

So I did the "blow" test (yes, I know, before all of you comment, it's my specialty) and it turned out perfect. Turn the carbs upside down the seal right up as they should. Just to be extra sure, I put the carbs in a cardboard box and then, using a syringe, I filled up the number one carb with gas until it wouldn't take anymore. I waited 10 minutes and here's the result - no leak.



So as I'm sitting there scratching my head, I notice there's another little spot under the bike again:



I'm wondering where the hell that's coming from as the carbs aren't even on it.

So I start tracing the fuel line backwards toward the tank and everything is bone dry.



But then, right after I took that picture, I noticed that the top of the rear brake master cylinder looked wet, so I pulled the side cover off. Behind that side cover, everything looks like it's covered with gas residue. I tried to use a flashlight to highlight it but it's pretty hard to see on the pictures.

Of note are the wires: where those wires look like they come out of the tank it is very wet back there.







I am at a complete loss. Any help would be greatly appreciated.

EDIT TO ADD: I filled up right before I came home and only put 4 miles on it. I just opened the gas tank and the gas level is right below the bottom of where the neck joins the tank proper and the tank is spotless on the inside.

 

[Fire-medic]

I'd normally expect a leaky slave cyl if it was an oil spot about inboard of the left rider's footpeg.

I've never experienced one, but maybe one of the gas tank seams has failed? The only gas tank electrical connection is the reserve gas sensor, on the bottom of the tank. Or maybe a pinhole?

It probably isn't it, but I suggest reaming-out the tank vent to ensure that there is no obstruction. If it was fully-obstructed, the bike would stop running and you would hear an inrushing of air from the gas cap being opened.

You could try dusting the area you suspect with some cornstarch, to see where things are wet, that might reveal the source. That reminds me of an off-color joke... .

Looking at the wet area, I suspect something to do with the gas filter being defective, or the hose seeping when the electric fuel pump is working, and pressurizing the system.

To help seat the carb rack and/or the stock airbox, I recommend my method. I call it the Happy Days method, as-in "sit on it Potsie."
https://www.vmaxforum.net/threads/1989-vmax-resurrection-thread.53264/page-2#post-535165

 

[Parminio]

It probably isn't it, but I suggest reaming-out the tank vent to ensure that there is no obstruction.

Where is that? The only hole I am aware of is the hole in the area where you fill it up that drains any gas you might spill to the ground.

 

[Parminio]

Never mind. Found it. Disconnected it at the tank and blew through the hose. It's pretty tough, but it's not plugged.

 

[Parminio]

To make matters even more weird: put the carbs back on. Bolted everything down, put it all back together. Ran it around the block.

Now no fuel is leaking, but it's running like shit. Yes, I synced. It idles perfectly, but I get on it and it has these little moments of hesitation in it.

Wondering if I knocked something loose in the carbs when I took them off, and turned them upside down testing the floats.

Probably did.

Damnit.

 

[sparky4123]

I had an XS1100 Standard with a tiny gas leak. You could always smell it and it was wet under the tank. I traced it down to the wire going into the fuel gauge sending unit. Somehow gas would get inside the insulation inside the tank and was weeping out at the connector. Always smell it but never a puddle.

 

[Radioguylogs]

I had the same problem on one of my XS1100's. I used POR15 patch to fix it:

 

[Parminio]

Well, as mysteriously as it started it stopped.

I'm beginning to wonder if I just overfilled the tank and when I parked it the pressure pushed it out the vent tube.

 

[Fire-medic]

Well, that's a new one! Something to check. Might be a good idea to buy a spare fuel sender unit while they are still available. You need it for the reserve function to properly operate.

 

[RempageR1]

I had the same issue when the vent tube was blocked (I sealed the tank and that blocked it). Then after filling up, the petrol warmed up and came out through the filler cap.

 

[MrMAX1985]

I had the o-ring sealing the fuel sender to the tank leaking on mine. pulled off and it was hard as a rock.

 

[Dorney]

If I try to get every drop, I can in my tank it will come out the vent hose unto the ground. That would be right under the center stand.

 

[Parminio]

If I try to get every drop, I can in my tank it will come out the vent hose unto the ground. That would be right under the center stand.

That's exactly where it was.