Diagnose Fuel Leak

[Thrud]

I've got a fuel leak in the carb bank of my 2000 Interstate.  I think it's somewhere in the area of the #5 carburetor (right side rear).  Drips profusely with the engine running.  No leaks with the engine off.  Could it be loose fuel line or bad seals in fuel rail?  Stuck float?  However, the bike idles just fine.

Can I attempt to diagnose the problem with the engine running with the bike's tank removed and supplying a temporary gas supply using an auxiliary fuel tank, such as those from Motion Pro?  Do I have to remove more than the bike's tank to get at the problem?  If yes, what about running the engine without the air box and filter?  Can this cause damage if run only a few minutes?

Thanks,

Steve

[F6BANGER]

Do the cheapest easiest thing first. Get a bright flashlight and look up under the tank between the carbs while its running. Maybe you will see where the leak is coming from. You will prolly have to eventually pull the tank to replace things.

[sandy]

If you have a hand held Mity Vac, apply a vacuum to the tubing on #6 intake. This will open the petcock. If it's leaking, it's probably the float valve is stuck open. When the engine is off, the vaccuum loss shuts the petcock.

[salty1]

Remove the seat, pull the tank, hook up a temporary fuel source and allow gas to flow without starting the bike. Get that bright flash light and see where the gas is coming from. It could be a fuel rail leak and it may stop after a day or two when the Oring(s) are saturated with gas and swell. I know this is a little more involved but doable. Keep us posted.

[whitestroke]

If you don't have a Mighty Vac, it just takes a light suction with your mouth and simultaneously push something in the tube.  I used a dowel punch, to keep fuel flowing with tank on.

And it won't hurt a thing to run the bike with the air-box off.  Just be careful nothing goes down intake.

[junior]

mine was doing the same except it was #4 it had sat dry forseveral months and when i fired her up it was leaking out of the vent on #4 carb it  healed itself after the nipple on the needle sofened up and i gave the tank a dose of ATF just to help lube the system

[Thrud]

I forgot to mention that I had fired up the bike for the first time since I put it away for Winter early last December.  Maybe the seals in the fuel system or one of the carb bowl float needles are dry or stuck.  I will let it sit overnight and try again today.  I'll report back.

[junior]

a light tap in the carbs will help set the needles on the floats and if the foats are stuck this will help free them up. mind you it doesnt take much, lust a few light hits with the handle 

[Thrud]

Okay, I started the bike this morning after letting it sit overnight.  No fuel leak whatsoever!  What gives?  Could it have been a stuck float needle or dry seals, or both?  I didn't touch any of the fuel system.

Steve

[junior]

there is a little rubber nippe on the float needle, that could have been dry, like i saud mine did the same thing this spring. thats why i put about 1/2 pt of ATF into my gas. and i also do it for summer storage for the snowblower

[salty1]

You may have had a fuel rail leaking. Glad it sealed.    Gas makes that old rubber swell. In your cas, that saves you a lot of work.