Recently my 2001 F4i has started pouring gas out of the left side while running. It runs down the vent lines and over the water pump, the flow seems to increase when I give it throttle. The strange part is that it doesn't leak when the bike is not running, and it only does it once every 5 or so times I start it. Today I re-adjusted the manual cam chain tensioner and tore it down, there's no signs of any leaks, everything still looks old and dirty, nothing has been washed clean from fuel and all the hoses and lines seem tight. I started the bike several times and let it run while doing my adjustments and it didn't leak a drop. Put it all back together, wheeled it out of the garage and fired it up. It started leaking almost immediately. It's done this to me 3 times now. I rode it probably 300 miles between the first time it happened and the second time with no issues. Everytime it happens I'm too pissed off to start taking it apart while it's running to catch it in the act. Any help would be appreciated.

 

You need to pinpoint where it's leaking from, my guess would be the FPR, since you said the left side. Check there first

 

I'll have to see if I can get it to leak. It never does it when I need it too, so I can never find exactly where it's leaking. The fuel evaporates by the time I can get it apart and there's no evidence of a fuel leak from anywhere. It's incredibly frustrating.

 

pull the tank, run the pump constantly (jumper it?) and wiggle and pull on hoses, poke injectors, etc. you'll find it. don't wait for it to find you while the bike is stationary, you need to move stuff around to help find it.

i'd guess return line broken or clamp loose

maybe one of the tank vents/overflow tubes too, try a full tank of gas and lift and move the tank to see what happens.

for safety, you need to stop riding and running the bike immediately until it is found.

if the leak worsens and it's truly near the engine, and a small engine fire happens, it'll probably melt more stuff, making the leak huge, then you will turn into a human fireball.

seen it happen before

 

Thanks, I didn't even think about jumpering the fuel pump. I stopped riding it after the second time it happened. The first time was a smaller amount so I thought maybe some was running out of a vent line somewhere because it wasn't constant. This issue is on the back burner for now. I low sided my dads bike going around a traffic circle on Sunday. Minor injuries (thank god for proper gear) but my riding season is done for this year I think. Time to rebuild.

 

Get a leak test kit. It's got a fluid that you put in the fuel (just a little) and a UV light and goggles. The source of the leak becomes instantly apparent.

Disclaimer: I know you can add the stuff to oil. Not 100% sure it's compatible with fuel but there seems to be several hits on Google about doing it with fuel, so it seems OK.