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Kinked petlock vacuum hose / fuel on floor

B

bill_face

Forum Apprentice
I'm not having an awful lot of luck. Or I know so little that I'm sequentially making every mistake possible.

Anyway a few threads down the list is one of me having left my carbs in Prime and finding fuel all over the floor and in the oil. So I changed the oil and got it going, and left them in ON position.

I came back to find another puddle of petrol on the floor. I did find the vacuum pipe was kinked the way I put it back on (I was concentrated on getting a fuel filter on the main fuel pipe.

Would a kink in the hose allow the fuel to flow? From what I can ascertain the petlock allows fuel to flow when there is a vacuum, so I could imagine that a completely sealing kink could be like a vacuum. If both pipes are disconnected the petlock doesn't allow the fuel to flow (which is the arrangement that it fuel tank is in at the moment).

Any advice would be appreciated, as I can't afford the keep refilling and changing oil this regularly :neglected:

Cheers
 
Let's start with the basics:

1. What model bike are you talking about?
2. What have you done to your carbs to date?
3. How are your hoses hooked up?

Pictures will be helpful

And,no, a kinked vacuum line will not allow fuel to flow
 
Question #4: Why do feel the need to install an EXTRA fuel filter? :-k

Depending on the year and model of your bike, fuel already goes through at least one, if not two filters before it gets to the carb bowl.

.
 
Sorry, I should have specified.

1) GS550 1979 VM Carbs
2) I've had the carbs rebuilt by my local bike shop. The guy there is really knowledgeable about old Japanese bikes and restores them himself. When I bought the bike it had some cheap pods on, but he advised me to change it back to stock airbox, and changed all the jets etc back to stock.
3) I'll attach a pic of the carbs with hose connections. The bigger hose (lower one on photo) is connected to the fuel outlet, and the smaller one to the vacuum connection on the petcock. I'll attach a photo of the petcock later as I can only upload one photo per post.
4) I attached a filter to try and prevent crap getting into the carbs. As I say they overflowed when I left it on PRI, which I surmised may be because a bit of gunk was stopping the float valves from closing. I did spray out the float needle orifices before reinstalling after the PRI leak

When I noticed the puddles of fuel caused by both leaving it on PRI and when I had it in the ON position this time, the overflow was running quite fast and stopping. I would expect it to be a constant drip/dribble, it struck me as a bit weird it was alternately running and not running. Not all the carbs were overflowing. When it was on PRI I saw it running from 1 & 2. And when i left it on ON I only saw it running from 1.

I just tried removing the tank and physically sucking on the vacuum pump. The petcock seemed to work fine. Just a small dribble after I stopped sucking. I then put the tank back on the bike and connected the fuel pipe to the carb, but sucked on the vacuum pipe. Nothing much happened, I could see fuel flowing through the inline filter, but I did get a bit of fuel in my mouth. Not a lot, just a taste, but I wasn't expecting it and I wonder if that signifies anything?

IMG_20181206_143019.jpg
 
Yes, that is a sign that your petcock diaphragm is ripped or not sealing. Time for a new petcock or to rebuild this one.
What carb does the vacuum line run too?
 
Stock VM Carbs (I think)

Here is a pic of the petcock. Is it standard for my model? ('79 GS550)

IMG_20181206_191533.jpg
 
Last edited:
Hard to say on the petcock itself. The fuel outlet looks like it is pointing down instead of towards the center, but otherwise it looks the same

From your photo in post #4, it looks like your hoses are correct on the carb side, fuel to the T between 2 and 3 and vacuum off the side of #3.

I can't say that I've seen a petcock dump fuel as you describe, but with 40 year old parts, anything is possible

Replace the petcock
 
Bill,

a couple of things that will benefit members who are trying to help you:

1. Go here - for the BassCliff site, full of information and tutorials http://members.dslextreme.com/users/bikecliff/
2. Go back to My Profile (at the top of the main forum page) then About Me and edit your signature to include your 1979 GS 550E. That way, we don't have to ask you what bike you're talking about.
 
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