Black Jack fuel leak

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Guff
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Black Jack fuel leak

Post by Guff »

My black Jack is leaking fuel. I've replaced the petcock and full line/filter. That didn't seem to do anything long term. Before I replaced those items, there was fuel in the air box. Any suggestions?

Thanks
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eggsalad
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Re: Black Jack fuel leak

Post by eggsalad »

Has this been going on for some time? Did you add fuel recently? Here's a lesson I learned the hard way:

Never fuel your scooter when it's on the side stand; always use the center stand. The bike needs to be level so you can accurately judge how much fuel is in the tank. Only fill your tank to within 2-3 inches of the filler hole, never more.

If the tank gets overfilled, liquid fuel will get into the evaporative emissions system. This system is designed to only handle fuel vapors - not liquid fuel. By overfilling the tank, the EVAP canister gets full of fuel. Then it's got to go somewhere. Under normal operations, the evaporative emissions system takes the fuel vapors that have evaporated off the liquid gasoline in the tank and feeds those vapors into the air intake system to be burned by the engine. So if liquid gasoline gets into the system, guess where it goes? Into the airbox. But that little hose can only pass so much liquid gasoline, and the EVAP canister still has more. So it leaks out.

If you haven't added fuel recently, you still might want to make sure your EVAP system is functioning properly.
scootERIK
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Re: Black Jack fuel leak

Post by scootERIK »

I would take a look at the float needle. All it takes is a little debris or wear and it won't fully close. If it doesn't close you can end up with gas in the airbox and on the ground.
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Guff
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Re: Black Jack fuel leak

Post by Guff »

I have recently gassed it up. I will be more aware and also inspect the float needle. Thanks for the tips.
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heyitsomid
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Re: Black Jack fuel leak

Post by heyitsomid »

I’ve gone through two gas tanks on my blackjack. The leak was at the base of the tank where the fuel line gets screwed on. The first time it happened I was riding full out through the hills and the mechanic was like this never happens. The next month I was back and they did the second replacement for free. Anyway for me I think it was caused by vibrational fatigue of the metal at that joint. Similar to how if you bend a paper clip really fast the paper clip more easily snaps apart.
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