Topic: New Gas Leak... Where to look?

[KB02]

Okay, so many of you, I'm sure, read my post on making sure you shut off the fuel petcock when you're not riding the bike. I am even taking my own advise on this, but now my bike is still leaking a bit when it sits in the garage. What the heck?!?!?

So, here's the run down:
I had to re-build my petcock. No biggy. all re-built and ready to go.
The carbs were wroking perfectly, then all of a sudden flood on the garage floor.
I'm sure that it's just a stuck open needle (or two) or something, I just haven't had time to fix it yet. I rode the bike to work the other day, just before turning into work, I turned the petcock off to drain the bowls a bit. All day long at work, it never leaked. The ride home. Same thing, turn off the petcock just as I turn onto my street. Small puddle on the floor in the morning.

I don't know. Maybe the Ducati is just scaring it and making it wet the bed. From what I can tell, the fuel seems to be coming from the  overflow tubes. With a couple of days off coming up, what should I look for here? Why would fuel leak if fuel is turned off? I'm very confused....

[Boomologist]

Does the bike lean a little more when parked at home? Sometimes it doesn't take much difference if you have a float adjusted slightly off from the others. Next time try putting a one inch thick board under the side stand.
Another possible is that setting outside at work, if it's hot, the gas may still be leaking slightly but evaporating before it gets to the pavement.
Be careful with gas inside the garage. Any source of ignition, pilot light, any electric motor, garage door opener, ..., can ignite the vapors. Even though there may only be a small amount on the floor there could be a huge amount evaporated and just hanging around waiting for that spark.

[Bob Wessner]

The carbs were wroking perfectly, then all of a sudden flood on the garage floor.

Your use of the term "flood" sure sounds like a sustained petcock leak to me. I know you rebuilt it, but still, that much fuel on the floor has to be coming from some place. Try disconnecting the lines from the petcock and put something under to catch any leaking fuel if there is any. I would try to rule that out as a source first.

[kghost]

Had a constant battle with my 350 doing this...............

After pulling the petcock apart for the 4th or 5th time I finally got my head out of my butt and actually looked and thought.

What I found was an area of corrosion and pitting on the face of the petcock body and the handle face.

Both areas were large enough to not allow adaquate sealing of the surfaces to thier respective side of the rubber.

If you look at the rubber that gets sandwiched between the two you will see that there are raised circles around each of the four holes on the seal.

Didn't take much corrosion to allow fuel to seep around those raised sealing surfaces.

I was successfull at sanding down the handle and eliminating the corrosion pitting on it. The valve body is a bit tougher due to the protrusions and being recessed.

Currently looking for a new/ servicable petcock for it. May have to modify a 750 one to get the single side outlet and a decent body.

[Boomologist]

If I read your post correctly, the petcock was leaking internally and not to the outside?
Provided the rest of the fuel system is correct you still should not have any leaky fuel.

[kghost]

Yeah well.......thats the theory...........

The reality of it is, if the petcock is allowing fuel to contine to flow to the carbs in the OFF position...

Then some venting thru the overflow will occur. I find it predominately occurs with temp changes and with angle of lean of the bike.

BTW the Vent system on the fuel tank is designed to allow air into the tank not vapor back out. Seems to me without the petcock closing off completely the fuel still gets pushed past the carb needles just a little bit.

[KB02]

Your use of the term "flood" sure sounds like a sustained petcock leak to me.

The flood was determimed to have been caused by bad float valves.

Fortunetly there are no appliances in the garage, so no open points of ignition.

And the bikes gas leaks out with the bike both on the side stand and the center stand.

And once again I have ridden it to work and it left no puddle there, but once I got home a small puddle occured.
As for this last part, I am going to agree with the whole being outside and the gas evaporating before it hits the ground theory.
Upon furhter inspection, I think I have isolated the leak down to one of my fuel filters. I will be looking into this a little furhter today (or tomorrow) and seeing what I can find on this. I'll let you all know.

[Bob Wessner]

I'm still a bit puzzled though, perhaps dense would be a better discription.  If it's either the float, or the fuel filter, the most fuel you should lose is whatever is in the one bowl until the level drops below the overflow opening, and if the filter, only the amount of fuel in the one line, then it should stop. Would either result in a flood?

[KB02]

Well, you know... I hadn't thought of that...

The origanal flood spewd forth, clearly from the overflow tubes on #1 and 3. I sat there ans watched the drips and watched the pours happen (This was after the rebuild... after I wasn't getting any fuel at all, thus persipiating the rebuild in the first place). When the littl puddles showed up I thought it may have been the same thing, bu the overflow tubes are dry now The fuel line, though, is wet with gas.

Now, the way that I have routed my fuel line might be adding to the problem since the line goes down under the carbs and then up to the fuel inlets on the fuel rail. This was the only way that I could get the filters in place, and I don't dare run without them. SO, there is a bit more fule available to the lines, admitadly, but I wouldn't thiknk enough to cause the issue that I am having, now that you mention it... Maybe my petcock is still leaking... GRRRRRrrrrrrrrrrrr.

Oh well. Only investigation will tell...
More to come

[TwoTired]

I had a CX500 that leaked out an overflows intermitantly.  It had a cracked overflow stand pipe.  It would leak a certain temps, and certain RPMs!

[KB02]

Okay, so the lajor leak has been found. It is a bad fuel filter. Looks like I will need to replace them with something a little better. I did also notice that with the fuel turned off, gas still dripped (albeit at a VERY slow pace) from the petcock while I had the fuel line off. We're talking one drip about every five minutes or so. Aything I should worry about?

[Bob Wessner]

Okay, so the lajor leak has been found. It is a bad fuel filter. Looks like I will need to replace them with something a little better. I did also notice that with the fuel turned off, gas still dripped (albeit at a VERY slow pace) from the petcock while I had the fuel line off. We're talking one drip about every five minutes or so. Aything I should worry about?

Yes, in my opinion. It may not sound like much, but overnight, or other prolonged period of standing/parking, this would eventually overflow in the carb bowls. The petcock should shut-off all fuel flow. I noticed in your first post on this you mentioned you had rebuilt the petcock. I would go back in there an examine things very carfully. Maybe there is a scratch or burr on some surface that needs to be perfectly smooth to seal properly. Let us know how it turns out.