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'86 Honda Fourtrax 350 4x4 Fuel system question

5836 Views 5 Replies 3 Participants Last post by  retro
New member here, first post. I found the forum searching for my problem, but didn't exactly find the issue I'm having. I have two '86 Honda 350 4x4's that are in great shape. I just rebuilt the carburetor on one of them and it runs great. Problem is that now when it is running, gas is coming out of the vent line from the lower back side of the fuel pump, and squirting out where it ends up in the headlight. The line has a tee in it and it also extends back to the rear brake drum. A side question is, why does the brake drum need a vent? I can pull the line off at the brake drum and the gas then runs out there instead of squirting out in the headlight. I wonder why the gas isn't running out in the brake drum with the line connected? Clogged maybe? Could anything with the carburetor rebuild have anything to do with this problem? Seems like a fuel pump issue and I really don't see how it could be caused by the carburetor rebuild, but it is a strange coincidence if it has nothing to do with the carburetor. Any help would be greatly appreciated.

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The vent line that is squirting fuel runs from the rear brake drum up to the fuel pump, has a tee that attaches to the fuel pump, and then extends up into the headlight. The vent lines on the carb extend up the other side of the machine into the headlight and down out the bottom of the machine to drain an overflowing bowl.
The fuel pump vent is not supposed to be tee'd into the brake vents. See the beginning chapter in the service manual for proper hoses and vents routing.

It sounds like the fuel pump (diaphragm) is leaking though, if gas comes out of the vent. OEM pumps are the only ones that work too, so its gonna be a bit costly to replace that. Hope to see your pics soon...
Yeah, OEM can be had for about $128:

Those vent hoses will need to be run up behind the headlight area separately, as Honda began to do in both '87 models. Did you get the fuel cleaned out of the brakes yet?
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