Check your petcocks!

[Rallyfan]

2006 with 45K on the clock.

My vacuum petcock (lower, on the frame) sprung a leak. It does this every 5 years or so, as it turns out. I bought a rebuild kit and for good measure an OEM replacement to I'll have two of them working hopefully.

However, I also discovered my tank petcock is seeping, apparently through the screw that turns the valve on or off. I'm glad I saw this! It's not seeping enough to drip (yet?) and for all I know it may have been doing this for years -- but it *is* doing it.

I ordered an aftermarket replacement and will replace both petcocks.

Have a look!

You don't want to be like Ghost Rider.

[Bluesmudge]

I also just replaced the tank petcock on my '06 GS500F  this year after finding a similar slow seep. 57,000 on the clock although I think it's more the years and storage condition and ethanol fuel vs the pure stuff  than miles. Mine wasn't leaking yet but was making the bike smell like fuel all the time. . The OEM replacement wasn't cheap so hopefully it lasts 15+ years like the first one. I think we are just coming up on the life expectancy of many of the rubber parts on the later bikes.

I've also replaced the vacuum petcock once with a used one off eBay. That was more than 10 years ago now, so that one's also probably due to start causing problems.

Us "F" model guys are finally starting to deal with all the things the "E" models have been dealing with for years. No more just banking on it being a relatively new bike. I also replaced my intake boots/o-rings and fuel and vacuum lines this year and I've got a set of ethanol resistant Viton orings that I need to find time to swap into the carb. Probably finally time to get a SS braided brake line for the rear brake too.

[mr72]

My vac petcock was causing a very difficult to diagnose problem, which is leaking fuel into the vacuum line causing the bike to run variably rich. A new vac petcock for my '92 was not available anywhere and the later model ones won't fit so I wound up putting a manual petcock.

[Sparker]

Thanks, I also discovered that the tank valve was slightly wet after I closed it for a week or so, while the tank was detached and I was waiting for shims. I have a 2001 model.

By the way, interesting detail: on my bike the fuel tank valve screw is facing outside. I mean the screw which we rotate with a long screwdriver to close the valve. It's facing outside and right into a tank wall, and I had to use thin pliers to rotate it. Weird, but maybe someone replaced the valve long time ago.

[Rallyfan]

Aha, I'm not alone!

I used an aftermarket tank petcock with OEM screw washers, and an OEM vacuum petcock.

I'm using OEM fuel lines with the asymmetrical ends, a screw clamp on one of them rather than the OEM spring clamp that I over-twisted and messed up, and a tank overflow drain that I cobbled together and have zip tied to route it.

This isn't a concours effort on my part... but then again I just don't want to catch fire. So far, so good -- everything back together and no juice coming out of anywhere that I can see.

I've found as mentioned that the NOSE always knows. You can smell a tank leak without lifting the tank to look at the tank valve, and you can smell a frame leak too. That's my plan, I'm sticking to it.

 

[Bluesmudge]

My vac petcock was causing a very difficult to diagnose problem, which is leaking fuel into the vacuum line causing the bike to run variably rich. A new vac petcock for my '92 was not available anywhere and the later model ones won't fit so I wound up putting a manual petcock.

How did you end up diagnosing this? I didn't even know it was something that could happen.

[mr72]

How did you end up diagnosing this? I didn't even know it was something that could happen.

Sherlock Holmes method. I eliminated every other cause of the bike running inexplicably rich, this was the only thing possible. Turns out it fixed it.