Author Topic: Leaky petcock versus fuel starvation?  (Read 407 times)

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Offline Bucky

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Leaky petcock versus fuel starvation?
« on: October 19, 2017, 08:49:32 pm »
2004 C10 with 24,400 miles.

Petcock has been weeping in recent weeks. I'm wondering if that could cause a presentation like the engine is acting fuel starved?

I read here it's time to change the petcock, but money is painfully tight at the moment. I will also probably see road salt within the next 30 days, so that puts the kibosh on winter riding for me. The cold I don't mind, salt and mag chloride I mind very much.



Thank you.

Note to you lucky Southern folk, magnesium chloride as a highway snow melting agent is as corrosive as something like salt on crack. Extremely corrosive.



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Offline Rev Ryder

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Re: Leaky petcock versus fuel starvation?
« Reply #1 on: October 19, 2017, 09:25:11 pm »
The petcock leaking will not likely cause any engine starving condition. 
IF the diaphragm on the petcock is leaking and you have an external leak, fuel is probably also being sucked up the vacuum hose into one carb and could cause some running issues.  But the big thing is always the same one...

IF the petcock is leaking INTERNALLY, you are in considerable danger of hydrolock IF you also have a float valve failing or sticking.  IF you have SiSF's overflow tubes, that threat is negated, but then there is the threat of fuel leakage on the ground.  No matter what the case, the petcock needs to be repaired or replaced.  It is a vital portion of your fuel system and is necessary for the safety of the engine and your household.  If you cannot repair it now, remove the fuel from the tank to eliminate risk or clamp off the fuel line with hemos/vicegrips/etc or pull the fuel line loose and stopper it off with a bolt/screwdriver/allenwrench/etc...  preventing fuel from entering the float bow or leaking on the groundl by any means will protect the engine and keep any kind of bad things from happening whether you have overflow tubes or not.
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Online MAN OF BLUES

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Re: Leaky petcock versus fuel starvation?
« Reply #2 on: October 19, 2017, 09:55:36 pm »
Well,.simple answer on my part, is that yes, it could effect like that... case in point:
If the o ring on the poppet valve is compromised, it can leak fuel past it, and into the chamber where those diaphragms live (there are 2, sandwiched on a plastic spacer..) , at that point, the fuel will swell, and render those rubber diaphragms into a state of non function... as a result, the fuel poppet will not fully open...this is usually seen as fuel dripping from a small vent orifice along the edge of where the diaphragm, and rear cover clamp everything together.. its kind of a "safety feature" with the sole purpose of saying to the owner "fix me"... you may not need a new petcock, they can be rebuilt reliably using the OEM diaphragm, which is $20. Stretch the spring about 1/4" when you reinstall... the OEM parts come with the new o ring fitted to the shutoff poppet.

$12.14
DIAPHRAGM,TAP
item: 43028-1015


http://www.ronayers.com/oemparts/a/kaw/500b25d7f8700223e478f689/fuel-tank-1-3


Ron Ayers... add shipping....

This is the OEM assembly, not a K&L "kit" replacement part.

I won't belittle Murph on anything he sells, but I wish he would carry the OEM diaphragm assembly...
In my experience with all parts Concours, this particular part, is one of the ONLY ones I prefer to buy as OEM only..
I have experienced sub standard results, years ago, with K&L on this part, and I fully know how the rebuild goes, so it wasn't an error on my part.

Anyway, fix it, its cheap. And they work.
« Last Edit: October 19, 2017, 10:25:48 pm by MAN OF BLUES »

30 YEARS OF KAW.....Rich R. (the other one..)  COG 5977  JUSTAMEMBAHNOW

Offline Bucky

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Re: Leaky petcock versus fuel starvation?
« Reply #3 on: October 19, 2017, 10:27:25 pm »


$12.14
DIAPHRAGM,TAP
item: 43028-1015


http://www.ronayers.com/oemparts/a/kaw/500b25d7f8700223e478f689/fuel-tank-1-3


Ron Ayers... add shipping....


Thank you for that. It's a whole lot better than $90.


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Offline works4me

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Re: Leaky petcock versus fuel starvation?
« Reply #4 on: October 20, 2017, 12:32:57 am »
I got my OEM petcock from Partzilla.
$67 + shipping.

Offline SteveJ.

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Re: Leaky petcock versus fuel starvation?
« Reply #5 on: October 20, 2017, 08:53:08 pm »
I got my OEM petcock from Partzilla.
$67 + shipping.
+1 for Partzilla. I just started using them, way frugal prices and so far excellent service, including over the phone.
Yeah, if you want true ram air tuning, you better be willing to ram some air! (SiSF)
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Offline Bucky

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Re: Leaky petcock versus fuel starvation?
« Reply #6 on: October 22, 2017, 04:13:42 pm »
Two things - when it hesitates, a hard throttle roll on temporarily clears it. As much as I might want to, I cant ride to work throttle wide open.  :great:

Yesterday on my 25 mile ride home, it stalled dead out just like it was out of gas. Engine just shut down. Luckily there was a spot to park safely. I parked for a while with petcock in prime position, and it got me home.

I believe it is fuel, not spark, but I'm still opened minded.

Money finally hit my account a day or so ago, and I ordered the petcock parts.

Ours is a two income house. Her income stopped. Too bad I am not an elected leader, or I could spend more when less comes in. . .
. . . and get away with doing so
 :)


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Offline SamSam

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Re: Leaky petcock versus fuel starvation?
« Reply #7 on: October 23, 2017, 01:35:54 pm »
I have an 2006 with 45k miles.  Owned since new.  Petcock weeps fuel when moved from on to prime.  Done  this for yrs with no issues.  I drain float bowls when parked for more than a few weeks.  Check bowls b4 starting for fuel.  Does this require a total rebuild or new petcock to repair.  What parts are needed?  Thanks in advance for reply.
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Offline Mettler1

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Re: Leaky petcock versus fuel starvation?
« Reply #8 on: October 23, 2017, 02:23:04 pm »
   Murphs' has a repair kit.   https://www.murphskits.com/product_info.php?cPath=1_94&products_id=121

  Also has a new petcock for you. I chose the new petcock. Quick and easy. :)

              https://www.murphskits.com/product_info.php?cPath=1_107&products_id=140

  I usually get my parts from Murphs' in 2 days.
« Last Edit: October 23, 2017, 02:30:53 pm by Mettler1 »
'94 Concours 115,000 miles-- 7th gear,2MM,KB fork brace,Over flowtubes,Stick coils,Tcro shifter,GPS,SiSF'sTorque cams,SPOOKFAK,block off plates, SS brake & clutch lines,KB risers, FENDA EXTENDA, emulators, SiSF carb Spa, Delkevic exhaust, Murphs' knee savers +grips, etc