Motorcycle Repair: Can dirty carbs cause a fuel leak on a non-running bike?, vent tubes, honda aero

Question
Hi Chris,

I have a pretty significant fuel leak on my '99 Honda Aero 1100. It drips about once every 9-10 seconds or so dead center of the bottom of the bike - just inboard from the kickstand. The fuel filter and pump (both located at the very bottom of the engine cradle) were both soaked so I changed out the filter but the leak is still there. Called the dealer service dept. to find out how much a pump install would be versus doing it myself. The service writer didn't think the pump would be it - said it sounded more like dirty carbs that may overflowing the vent tubes and is just running down the inside and wetting the pump and filter along the way. He's proposing doing a carb cleaning first. I can probably do that myself but wanted to check in here first before tearing them apart or letting them do it.  Does this sound like a plausible possibility?

FYI - there are two more clues that have me REALLY questioning whether or not this service writer is anywhere near the right track.

1) It just started leaking out of the blue while sitting in my garage. The bike was not running and had not run since I winterized it. I live in a cold weather climate and it started right in the middle of a VERY cold spell - making me think perhaps moisture in the fuel may have split a fuel line - but they all appear to be dry. Perhaps moisture may have ruptured the fuel pump casing?

2) It leaks just from gravity. When I closed the fuel shutoff, it leaked for a couple days and stopped. When I re-opened the shutoff, it took a few days, but eventually it started leaking again without the bike running at all. I'd think air pockets in the fuel lines post-pump would prevent the fuel from running UPHILL to the carbs, fill them, and then overflow AROUND the vent tubes - although I realize the laws of physics says a 'head' of fuel can go down through the filter/pump area and then back up to the carbs because they are still below the tank.

Sorry for the long length, but I'm trying to be detailed.

Thanks,

Mark

Answer
Hi Mark.

The service writer is most likely right.  The weather can have a very dramatic effect on the seals in the fuel system.  Fuel, in a bike which has been stored will also leave a residue that we call varnish.
 Varnish will ruin seals and gum up the carbs as well, which means that you will also need a proper carb cleaning as well as either cleaning out or resealing of the tank.
 You will need to do this every year that you leave fuel in the system while the bike is in storage.  There is no additive that you can put in the fuel that actually work as advertised, so don't waste your money on them.
 Just make sure that every drop of fuel in the bike is either burned out of the system or drained and used elsewhere.  Replace the fuel with fresh fuel when you go to ressurect the bike after the winter.

That hose that the service writer mentioned is an overflow drain line.  A seal in the float system has failed and that is the problem, causing the fuel to bypass it and drain the overflow out of the bike.

Good luck and ride safe.
FALCON