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Thinking Through a Fuel Leak


Guest coffeebrake

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Guest coffeebrake

Before I buy parts and pull the carbs, I'm thinking through a fuel leak to make sure I'm understanding it right.

My '86 VFR700 has begun leaking a lot of fuel when it's running. It seems to be coming from the rear left carb. I'm assuming this is a float needle gone bad.

The petcock has always leaked, I installed an in-line on/off valve that I can reach through the fairing. But I never turn it "off" unless I'm pulling the tank. I relied on the float needles to stop the flow of fuel.

Well, I think at least one float needle is leaking and the only reason it hasn't hydrolocked is because it has a fuel pump instead of gravity feed.

Does this sound right? If it was a float bowl gasket, it would seep all the time, right? But this pours fuel only when the engine is running. The oil doesn't smell like fuel, thank goodness.

I'm also puzzled at the sudden nature of the leak. It went from a slight fuel smell one day, to dripping fuel all over the running engine the next.

Any ideas? I don't mind working on the carbs, goodness knows I've been through them over and over while resurrecting this wreck. I'd just like to wrap my head around the problem and have all the parts ready and waiting when I pull it apart. I love riding this bike and don't want to have it offline any longer than it has to be.

I really appreciate anyone's advice/experience.

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Good call, I did check the fuel line with the bike on the lift and running. The fuel line is dry, it's not leaking. The bottom of the back left carb, though, is pouring fuel.

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  • Member Contributer

sounds like a stuck float, tap it with a hammer or something, The rubber tips of the needle valve will get worn after so many years, does she run a little rich also??

good luck

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The plugs looked pretty good, so not too rich if at all.

Wow these float needles are quite spendy. I wonder if there's a cheaper alternative....

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I'll check 'em out, thanks!

Honda wants to sell the valve needle with a new seat. I was just gonna polish the seat and put in a new needle.

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It's in the fuel rail. The rear fuel rail is POURING fuel when the bike is running. I hope I am lucky enough that the o-rings in my Harbor Freight kit will fit. Otherwise, I'll have to order from Honda.

I miss riding my VFR so much....I have other bikes, but they're not VFRs....

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Hi CB....How ya doin? I had this same problem with my VF500F. I got a set of o-rings for the bowls and fuel tees from Jamie Daugherty. Included were a set of allen head bowl screws, good deal. Might want to check the tees carefully, they tend to get cracked with age. If the tees are cracked/damaged, aluminum replacements are available from Billy Carr:

Billy Carr billycarrjr@earthlink.net

20706 State Hwy. 19

Canton, TX 75103

http://www.daughertymotorsports.com/Modifiedshock.html

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Hi Creaky, great to meet you in GA recently!

Thanks VERY MUCH for the info, I'm still hoping I get off easy. Also have a rack of parts carbs though I doubt the fuel rail is intact.

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Hah, fuel line after all. Was about to break the carbs off the rack and finally saw a cracked line. I've replaced it and hooked the carbs back up to the fuel pump, and no fuel is coming out when the starter motor is turning (and the fuel pump is operating, with fuel in the line. So I'm hoping to re-install and ride tomorrow.

I'll just take the float bowl gaskets I ordered and put them aside for later, as a float bowl leak won't deadline the bike like this line did.

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