Bad auto petcock maybe?

The automatic petcock valve on my KZ550 LTD 1982(C3) seems to be letting fuel flow even in the ON position while the bike was parked in the garage. I just filled the gas tank to full for the first time this morning an did not notice any leaks then but wife found the leak at the inline fuel filter when she got home later in the evening. It was dripping pretty bad when I finally got home though my wife had managed to slow the leak by twisting the fuel tube. Now it doesn't look like the petcock itself is leaking but for some reason, the ON position didn't seem to turn off the fuel flowing in from the tank. It was the same story in the RESERVE position too. Am I looking at a bad petcock is something wrong with the vacuum system?

And can I use this petcock switch without connecting the vacuum hose? In that case, I'm guessing I'll only be using the PRIME position for feeding fuel to the carbs and the ON/RES positions will just be OFF. Will that work or do I have to repair the petcock or replace it with a non-vacuum petcock?

Any suggestions to what to look for and how to fix the leak in the ON/RES positions will be much appreciated.

z1enterprises will have a rebuild kit for your stock Vacuum Petcock, also a replace manual one that may require an adapter. There is a spring and an O-ring on the one side of the diaphragm that can fail. Not difficult or expensive to repair.

You can either get a complete petcock rebuild kit or just a diaphragm kit.

I opened up the petcock and the thing looks to be in a pretty good shape. The O ring was just fine and the diaphragm isn't bad either. I'm just not totally comfortable with the fact that there is really no true off switch and when the vacuum mechanism fails, It leaks like crazy. Can I just not hook up the vacuum tube and only use the PRI switch as ON and use the other two as OFF? Or replace the entire thing with a manual switch? And do I really need an adapter for a manual one?

Oh, and the spring is fine too. Everything looks new on the inside.

If you want something cheap and easy, you could go this route: www.z1enterprises.com/ItemDetails.aspx?i...+Line&item=MP12-0035
As far as a new Petcock, call Z1 and see what they have that fits. As I don't see anything on their website for the 550. Also at Pingel I don't see a 550 listing. But the guy's at Z1 will know.

Mine looked new too, but the diaphragm was bad.

Thanks for all your input. And it was another newbie error. I kept looking at the diagphram but when I opened the actual switch side, noticed that the valve gasket (the round rubber thingy with holes) was pretty messed up. I'm just going to get a rebuild kit from Z1 and install it. Looks like this should work:

www.z1enterprises.com/ItemDetails.aspx?i...uum)+&item=KL18-2698

I've had good luck w K&L parts. Their stuff is made in Japan.

Bunty27 wrote: Thanks for all your input. And it was another newbie error. I kept looking at the diagphram but when I opened the actual switch side, noticed that the valve gasket (the round rubber thingy with holes) was pretty messed up. I'm just going to get a rebuild kit from Z1 and install it. Looks like this should work:

www.z1enterprises.com/ItemDetails.aspx?i...uum)+&item=KL18-2698

www.z1enterprises.com/ItemDetails.aspx?i...m%29+&item=KL18-2698

Good Fortune!

I repaired mine with genuine Kawasaki parts. No problem since. I'll see if I can find the parts numbers that I purchased.

I got the petcock rebuild kit from Z1 and was able to install it without any issues. I'll test it over this weekend and I'm sure everything will work fine now. Thanks much to everyone who pointed me in the right direction.