possible solution for one of the petcock failure modes

[derm]

Hi all,
This is my first post in this group. I have a 94 c10.

I was thinking that the two possible failure modes for the petcock were
1. Diaphragm failure
2. Valve failure due to
    a. Oring failure
    b. Dirt holding valve out
    c. Spring failure

For failure mode 1, one possible solution might be to run the vacuum line from the diaphragm side of the petcock up under the tank, poke it up above the fuel level and then bring it back down to the carbie.This would possibly have the effect of limiting the amount of fuel entering through the vacuum port in the event of a diaphragm rupture.

My questions are:
1. Is this a common failure mode?
2. Would this be likely to work?

TIA

[m in sc]

 its a vacuum line so fluid would be sucked in regardless.  as far as raising it above the tank when sitting... that would work but only until it was fired up. and running. That failure scenario would only happen if the o-ring and diaphragm failed at the same time. highly unlikely.
But would warrant a new, rebuilt or manual petcock IMHO.
 

[gpineau]

My solution.  Works like a champ. No more worries.
And the price dropped 50% since I bought mine.
https://www.amazon.com/gp/product/B00EP1N39A/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

[derm]

its a vacuum line so fluid would be sucked in regardless.  as far as raising it above the tank when sitting... that would work but only until it was fired up. and running. That failure scenario would only happen if the o-ring and diaphragm failed at the same time. highly unlikely.
But would warrant a new, rebuilt or manual petcock IMHO.
 

Thanks for your response.
The fuel sits behind the diaphragm and wouldn't need the failure of the oring to allow fuel down the vacuum line.
You're right about the vacuum sucking the fuel down into the outlet side of the carb when it was running but when the motor was off, I believe it would be unlikely to syphon since the end at the carb is not submerged.

[derm]

Thanks for your response.
The fuel sits behind the diaphragm and wouldn't need the failure of the oring to allow fuel down the vacuum line.
You're right about the vacuum sucking the fuel down into the outlet side of the carb when it was running but when the motor was off, I believe it would be unlikely to syphon since the end at the carb is not submerged.

Thanks for your response. I clicked on the link but it states it's unavailable. I bought this one previously but can't seem to fit it into the bike:
https://www.ebay.com.au/itm/Inline-Petrol-Fuel-Lock-Off-Solenoid-Valve-With-Manual-Opening-Tap-/232664826748?mkcid=16&mkevt=1&_trksid=p2349624.m46890.l49286&mkrid=705-154756-20017-0

I found a similar one to yours on eBay for less than AUD$50 delivered from UK to Australia. How well did it fit on your bike and does it ever cause issues?

[m in sc]

On the 2 the c10's i currently own have 1 new and one rebuilt petcock, but also a manual inline cutoff in-case the o-ring fails.  The solenoid listed above is a very good solution for some. Me? i have no problem cutting the inline valve on and off. (i have a gaarge of vintage bikes so its required on those)

these petcocks last 10,15,20 years. a properly rebuilt one will last just as long as long as the tank is clean.  .02

 

 

[Freddy]

I have one of these on my bike. 

eBay item number:165013649477

[derm]

Any chance you could please post photos Freddy? I'd really appreciate knowing how and where to install it.

[Freddy]

You can't see it with the tank installed but is fitted in the fuel line between the petcock and the carbs.  The power feed is taken from an ign coil, which allows fuel to flow only when the key is on obviously. 

[derm]

Did you install it with the solenoid down?

[bowtie39]

Trying to reinvent the wheel

[m in sc]

Trying to reinvent the wheel

+1.  and, what typically causes failures, crud in the tank, will also affect a solenoid valve. just fyi. Is it convenient? yes. but thats about it.

[bowtie39]

+1.  and, what typically causes failures, crud in the tank, will also affect a solenoid valve. just fyi. Is it convenient? yes. but thats about it.

Thank you!

[derm]

This is an interesting discussion. So, what are people's thoughts on running the vacuum line up under the tank so that it is above the fuel head to protect against fuel running into the inlet port (when the engine is off) in the event of a diaphragm rupture?

In terms of crud in the tank, as part of my bike's extensive maintenance/rejuvenation, I've lined the tank with epoxy. I'm also going to put a rebuild kit through the fuel tap.

[Freddy]

Did you install it with the solenoid down?

No, it's horizontal.  On your other point, the vacuum line's not the problem - it's leaking seals and seats.

[derm]

Thanks for your reply

[derm]

its a vacuum line so fluid would be sucked in regardless.  as far as raising it above the tank when sitting... that would work but only until it was fired up. and running. That failure scenario would only happen if the o-ring and diaphragm failed at the same time. highly unlikely.
But would warrant a new, rebuilt or manual petcock IMHO.
 

m in SC, I can see that what you said about the dual failure is correct now that I'm rebuilding the petcock. I apologize for doubting and contradicting you.

On balance from all the advice everyone has posted, I don't think I'll bother with the solenoid. I can see what people are saying about crud being the underlying cause which would also eventually affect the solenoid valve, delaying the inevitable.

I can also see that the vacuum line is not the issue since there would need to be a failure of not only the oring but also two diaphragms (with a weep hole between them).

I've got an epoxy coated tank, new seal and diaphragm kit in my pet cock and a new fuel tank cap on its way so hopefully that will suffice to provide freedom from the hydrolock nightmare.

Thanks everyone.

[bowtie39]

One last opinion.......the fuel line is kinda important.  Over the years I've found using a Silicon line works best as heat, ethanol etc don't degrade it.  Have had lines collapse, usually at the curve where it comes up from the fuel rail. Engine heat can make the line weak.   

[jacksdad]

I think people are going over the top here: the vac fuel tap works most of the time, often lasting decades (I've restored dozens of jap bikes over the last 40 years) and have seen very few failures, all of which have been fixed with the $30 of genuine Kawasaki parts).
But if you are still worried, fit carb bowl overflow tubes!
I drilled and tapped the bowls and fitted brass tubes, along with Loctite and a stainless locknut, or buy Steve's modified parts (if he stll does them?)
Don't get carried away...the simple answer works best 

[m in sc]

i agree with ^.

I run the inline cutoff 'just incase' but as stated above, most of my bikes are vintage and turning a petcock off when parking is second nature.  But i have dealt with hydrolock in the past from a different concours sitting and it seeping past (and a cb750 and an H1, etc) for extended periods, and it wasn't pretty.