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Gas pouring out the carb vent line

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I go to start my DRZ this spring after sitting all winter, and gas is pouring out of the carb overflow. Only when running or cranking, so the vacuum petcock is working. OK, figured the carb got funky.

 

Pulled the carb out and apart, and it was spotless inside. Zero gunk, dirt, nothing. Needle and seat look perfect.

 

Put it back together, and upon initial startup is pissed gas for a second and quit. Rode it around a bit and it was fine. That was two weeks ago.

 

Go to run it last night, same shit, pissing gas.

 

'03 DRZ400 S, stock CV carb. 6,500 miles.

 

I notice the float is all plastic. Is there a possibility that either its age, or the Ethanol in the fuel, or whatever, has caused the float to get tight on the pivot pin and make it not move correclty?

 

Other thoughts? It's always had Stabil in the fuel over the winter, but not a drained carb.

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It could be a few things:

  • o-ring on needle valve seat (leaking)
  • damaged needle valve and/or seat (sides), causing the needle valve to bind and not properly open/close
  • damaged needle valve tip (rubber)
  • damaged float (cracked/pinhole),  causing it to sink and keep the needle valve/seat open
  • float level too heigh
Edited by bmwpowere36m3
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It could be a few things:

  • o-ring on needle valve seat (leaking)
  • damaged needle valve and/or seat (sides), causing the needle valve to bind and not properly open/close
  • damaged needle valve tip (rubber)
  • damaged float (cracked/pinhole),  causing it to sink and keep the needle valve/seat open
  • float level too heigh

 

 

Yea, shoulda done a search first, lol, read about the oring going bad. If nobody has ever had the float get tight in the pivot pin, I'm thinking maybe the oring is it, but I'm questioning why it didn't piss fuel after I put the carb back together and ran it, but then started leaking again last night. Needle moves in the seat great, blow test was as it should be, rubber on needle looked great. Float had zero fuel on the inside.

 

I guess I'll pull it apart again and check the seat oring.

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for a quick temptorary fix you can hit the carb body with a hammer handle or screw driver handle to jar the float loose.

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If it is leaking after you run it then the petcock is going bad or already there. Think about it. Only after it has been sitting does it leak. So gas is flowing from the tank. Petcock or something in the float/float needle assembly is allowing the fuel to flow. I would also check your oil for fuel contamination. The petcocks sometimes weep when they are going out. From a hole in the petcock vacuum mechanism or through the fuel line to the carb.

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When you leave gas in your carb during storage the float valve (needle) is constantly pressing against the seat.  This will eventually cause it to leak.  Float valve (needle) could visually look ok but may not be.  Moose Racing offers a complete rebuild kit cheaper than a 'needle & seat' from dealer.   :thumbsup:

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Took it all back apart last night. The oring around the needle seat was still soft and pliable, but looks like it could possibly be leaking, the bore in the carb body around the oring had some hard crud in it where the oring sits. And while my eyes aint what they used to be, the orng may have some flats on the O.D. Cleaned that all out real good, and will try and find an oring today. And some new bowl screws, lol.

 

I'll bench test it before putting it back in the bike this time.

 

With bike not running, the only way it'll leak is with the petcock on "Prime", so that tells me it's not the petcock?

 

Thanks for the info on Moose offering a rebuild kit, $60 for a Zuke needle and seat chaps my ass, lol.

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