How do you know if petcock is bad?


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LAB3
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How do you know if petcock is bad?

Post by LAB3 »



Ended up with a problem in my fuel system yesterday. There was no gas showing in my filter and I pulled the inlet hose off the fuel pump, no flow in either petcock position. Disconnected the hose at the petcock and had zero flow there. Reconnected the fuel line to the petcock and put it in the "res" position then blew through it, there was definitely something blocking the flow of gas and it quickly cleared itself out

After making it home I used a large hypodermic type thingy with a piece of fuel line on it and worked the plunger several times in and out. There was no sediment in the gas and fuel flowed easily in both petcock positions.

Sure enough, the same thing happened this afternoon, a plug in the petcock or somewhere upstream of it. Popped off the inlet fuel line off the fuel pump and blew through it, same outcome, whatever was there cleared itself out. The best explanation is that the tube feeding into the petcock from the tank is where the problem is but it could also be the petcock itself.

After just now finishing off draining the gas and inspecting the tank, it appears to be clean and here's my question: How often does a non-leaking petcock go bad? If I drill the rivets to get inside, do I have a reasonable chance of it not leaking once I screw it together? Is rebuilding the petcock worth the effort or should I just replace it?


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joecoolsuncle
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Re: How do you know if petcock is bad?

Post by joecoolsuncle »

never saw a non leaking petcock go bad. you are describing a fuel tube (pickup) screen getting clogged. without pulling the tank, bet bet is to siphon the tank with the largest diameter hose you can fit in there. think shop vac. but siphon wont burn you knutzes like a shop vac. :D

probably rust and sediment is hovering around the fuel pickup like space-x satellites and will continue to cause you mass hysteria just like elon does.

paek her on an elevated surface and siphon the tank, filter fuel through a pair of dirty drawers and pour back in tank. holler back.
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LAB3
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Re: How do you know if petcock is bad?

Post by LAB3 »

joecoolsuncle wrote: Sun Apr 03, 2022 7:58 pm never saw a non leaking petcock go bad. you are describing a fuel tube (pickup) screen getting clogged. without pulling the tank, bet bet is to siphon the tank with the largest diameter hose you can fit in there. think shop vac. but siphon wont burn you knutzes like a shop vac. :D

probably rust and sediment is hovering around the fuel pickup like space-x satellites and will continue to cause you mass hysteria just like elon does.

paek her on an elevated surface and siphon the tank, filter fuel through a pair of dirty drawers and pour back in tank. holler back.
THAT is what my exact thinking is. However, I'm still wanting to open up the petcock to check for any debris which may be in there out of curiosity if nothing else, needless to say I'd hate to open it up only to have a partially working or leaking petcock when I'm done. As to filtering the gas, I only have one pair of drawers to use and with a wedding coming up I'd appreciate an alternative method of filtering. :roll:
I'm selling good clean fresh hay. If you want some that's already passed through the horse, that comes a little cheaper!

The best advice on internet motorcycle repair forums comes from posting the wrong answer to your own question.
joecoolsuncle
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Re: How do you know if petcock is bad?

Post by joecoolsuncle »

LAB3 wrote: Mon Apr 04, 2022 11:09 am
joecoolsuncle wrote: Sun Apr 03, 2022 7:58 pm never saw a non leaking petcock go bad. you are describing a fuel tube (pickup) screen getting clogged. without pulling the tank, bet bet is to siphon the tank with the largest diameter hose you can fit in there. think shop vac. but siphon wont burn you knutzes like a shop vac. :D

probably rust and sediment is hovering around the fuel pickup like space-x satellites and will continue to cause you mass hysteria just like elon does.

paek her on an elevated surface and siphon the tank, filter fuel through a pair of dirty drawers and pour back in tank. holler back.
THAT is what my exact thinking is. However, I'm still wanting to open up the petcock to check for any debris which may be in there out of curiosity if nothing else, needless to say I'd hate to open it up only to have a partially working or leaking petcock when I'm done. As to filtering the gas, I only have one pair of drawers to use and with a wedding coming up I'd appreciate an alternative method of filtering. :roll:
lol. yep, i thought that was the mandatory filtering method when doing redneck repairs. lol. btw, hold a plastic bag over the petcock as you remove the screws, or rivets, so all the parts stay in the bag. spring and or wavy washers and orings like to leave the area once set free. i always lubed the orings with Vaseline and slowly turn the valve back and forth as you are tightening the fasteners. the machined edge likes to slice the side of the oring.
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Re: How do you know if petcock is bad?

Post by OldguyGlen »

If it is blocked on both ports, then its probably a petcock problem. If it was just a screen problem it would likely only be on one port. I have drilled the rivets and rebuilt my petcock with success. i even did a poor job of drilling resulting in a wobbled out hole. But machine screws and nuts held ok on the rebuild. Been 3 years and no leaks or problems.
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Re: How do you know if petcock is bad?

Post by winguyjo »

i would remove the petcock and apply compressed air in all 3 positions, keeping a close eye on what, if anything, comes out. maybe have those drawers ready to catch any chunks. oh wait, you are saving them for the wedding. just watch closely then.
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Re: How do you know if petcock is bad?

Post by LAB3 »

OldguyGlen wrote: Mon Apr 04, 2022 2:36 pm If it is blocked on both ports, then its probably a petcock problem.
Bingo! My assumption is that if they BOTH are blocked then the petcock is what the two have in common. It'll be a couple of days before I can get to it but I'll report back.
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The best advice on internet motorcycle repair forums comes from posting the wrong answer to your own question.
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Re: How do you know if petcock is bad?

Post by LAB3 »

Update: It wasn't the petcock at fault! Bought a rebuild kit and pulled it apart and it was clean as a whistle inside. The inside of the tank is CLEAN so the blockage must be inside BOTH of the tubes inside the tank. Looks like I'll be pulling the tank and soaking it with vinegar this weekend.... ugh!
I'm selling good clean fresh hay. If you want some that's already passed through the horse, that comes a little cheaper!

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Re: How do you know if petcock is bad?

Post by OldguyGlen »

A blockage on both tubes, in a clean tank seems highly unlikely. Pulling the tank is a big job. I'd first try blowing back into the two ports where the petcock mounts. Just by a piece of tubing and your mouth for starters. Compressed air next. Whatever you learn will help decide the next move.
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LAB3
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Re: How do you know if petcock is bad?

Post by LAB3 »

OldguyGlen wrote: Sat Apr 16, 2022 2:28 pm A blockage on both tubes, in a clean tank seems highly unlikely. Pulling the tank is a big job. I'd first try blowing back into the two ports where the petcock mounts. Just by a piece of tubing and your mouth for starters. Compressed air next. Whatever you learn will help decide the next move.
Yeah, I've come to the conclusion that pulling the tank is probably a bit extreme at this point. Seeing as I don't have an indoor place to work on the bike I'll probably do as you described first, I've also seen in another thread that using an old piece of speedo cable connected to a drill is something else to try out. Would have done that the other day but whenever I go to work on the bike
I tend to get far too many neighbors coming out to "Help" which leads my mind astray.
I'm selling good clean fresh hay. If you want some that's already passed through the horse, that comes a little cheaper!

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Re: How do you know if petcock is bad?

Post by OldguyGlen »

I appreciate the challenges of having no garage. Perhaps you are light in the tools dept too. You could ream out the tubes as you mentioned. Other "tools" could be an electrical wire, long zip tie, or thin somewhat stiff plastic tube. Be sure to flush out anything you loosen up. You probably will loosen up some amount of crud even in a non-plugged tube.
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Re: How do you know if petcock is bad?

Post by joecoolsuncle »

running a cable on a drill is suicide to 40 yer old cancerous metal tubes. the pickle juice is much gentler. you have already blown through the petcock by mouth only, it is how you got to this point. if you must, use a weedeater string as opposed to a 6 million rpm shredded wire roto rooter. dont bruise daa baby.
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Re: How do you know if petcock is bad?

Post by LAB3 »

Actually Joe what I'm hoping for is to create a spark and have it explode so I can collect the insurance money to put toward an ST1100. :mrgreen:
I'm selling good clean fresh hay. If you want some that's already passed through the horse, that comes a little cheaper!

The best advice on internet motorcycle repair forums comes from posting the wrong answer to your own question.
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Re: How do you know if petcock is bad?

Post by joecoolsuncle »

LAB3 wrote: Sun Apr 17, 2022 7:18 am Actually Joe what I'm hoping for is to create a spark and have it explode so I can collect the insurance money to put toward an ST1100. :mrgreen:
please document that. i it works, i will do the same! wait, insurance only pays actual cash value. lol. that wont buy lunch. besides, mine will exploded right after i get everything fixed!
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Re: How do you know if petcock is bad?

Post by old.wing »

Moin, did You Check the fuelpump? If it doesn’t produce a vacuum, the Pertcock will not open and there is no fuel in the line. It is a Vacuum fuel tap.
Good luck 🤞
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Re: How do you know if petcock is bad?

Post by Dalydude »

I found replacing the petcock was simple, easy, and with a new petcock, confident it will work properly for another 40 years.


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