Intermittent fuel leak

[kiwiaudio]

Lately, I've been noticing the occasional few drops of fuel on the ground on start up when cold. It will quit before I even get out of my driveway and never be seen again sometimes for days.

Today, after the bike had sat for about two weeks, fuel literally poured out from around the right side. Probably lost about a pint before I got her shut down. I immediately pulled the side cover and noticed fuel on the electric lines that I assume go to the sender unit on the inside right of the gas tank?

Everything else, including the rubber fuel lines are dry.

So I start the bike to determine where it is coming from, and ....nothing !!!! No Leak !!!!

This is no more than 5 mins afterward !

 

I shut the bike down at this time and popped the tank lid to see if it is pressurized, and it was not.

 

Is there perhaps a grommet surrounding these wires that is prone to leaking?

I cannot imagine a scenario involving going from a large leak to nothing by only removing the side panel!

Maybe it does not like that side panel huh !!

 

What's going on here ? Anyone ?

[MattP]

I had a similar issue, on-again off-again fuel leak on the right side. On mine, it was the rubber fuel lines aft of the ODs. They had the factory crimp-on clamps. I replaced the small pieces of fuel line and used FI-rated clamps, and that seems to have fixed the issue. I can't really answer as to why it was intermittent, but maybe (in my case) as the bike heated up and pressurized fuel caused the rubber fuel line to swell under the not-so-tight factory clamp, the leak would go away. I don't know. Hope that helps.

[kiwiaudio]

Yes, I'm familiar with that leak as I've had that happen as well Matt. Although that fuel leak was also intermittent, this leak is not in that location. I'm pretty sure the fuel pressure is higher on cold start up, perhaps to facilitate a richer mixture, and that may explain the intermittent part of both scenarios.

 

I've now pulled the tank and everything is dry except the electrical lines (3 smaller 18 ga wires that I assume are the sending unit wires). They are connected to a white plastic plug that I'm thinkin may be the leaking area, but I'm just guessing.

Looking directly at the fuel pump mounting plate, I can see dust around both rubber fuel lines at the connections that would be washed away if either one were squirting gas.

 

While I'm banging this around in my head let me pose a few questions:

 

-Does the tank get pressurized normally? (I've never heard that tell tale air rush when opening the gas cap)

-Would the canister somehow be causing this temporarily?

There was a little moisture in one of the cannister lines when I disconnected it, but it was not gas.

-Is there a right and wrong way to connect the fuel lines? - perhaps they were reversed at some time?

-Perhaps the canister lines were reversed ?

 

It is interesting that this major leak happened on first start up after the longest riding down time I've had this season. Coincidence ?

Then 5 mins later I have no leak at all !

[kiwiaudio]

I know that every fuel leak I've read about on this forum is coming from the quick disconnect/ manifold area, but this leak was pouring down the right front directly onto the header pipes - eeekkk !!! I made a beeline for the fire extinguisher faster than I would have thought myself capable of !!

 

I'm now just standing here looking at my gas tank off the bike, wondering what to do next - I see a few beers in my immediate future !!

[kiwiaudio]

Pulled the pump out and replaced the filter while I was in there. Other than some questionable clamps, I saw nothing unusual. Replaced said clamps and reassembled which is easier said than done !

I bought about 4' of 5/16 fuel line and rigged the tank up off the bike.

Drank a beer and thought about it !

Ignition on and the pump stroked for a few seconds.

Fired up the bike and took a good look at everything.

No Leaks, but I really haven't done anything!

 

I'm tempted to leave the tank off the bike for a while to see if it comes back.

 

Man, intermittent faults are frustrating !

I searched this site for fuel leaks, and although there are a bunch, I don't see any incidence of leaks around the fuel pump plate.

 

Anyone?

[Rx_Mich]

I found a pin-hole leak in my tank on a R1100RT along a seam in the right saddle area above the horn where it slides onto the frame. It would only leak when the fuel was above that level and a ride to heat from the engine causing remaining fuel to expand and put extra pressure on the contents. I would find fuel on the hangar floor but not see any on the tank. You are probably not going to but clean the tank good and then look for a stain. If you need help, there are dyes available to add to the gasoline to make detection easier.

 

I found it after a ride when I was smelling a little gas so I went inspected the area with a flashlight and saw some moisture in that area. A little dab of "fuel lube" on the seam and it immediately stopped. I cleaned the area with acetone and applied a fiberglass patch. NO MORE LEAK.

 

Other areas I did some preventive maintenance:

1. removed O-ring under gas cap neck attachment to the tank. Found a dirty O-ring and seat. Cleaned seat and put a small coating of fuel lube on the o-ring and re-attached.

2. Anti-fork dive shock had the threaded rod touching the under side of the fuel tank causing visible wear. I cleaned this up, reinforced with a fiberglass patch and put a rubber cap over the rod.

 

Hope that helps, Bob

[Ken H.]

Does the tank get pressurized normally?

No

Would the canister somehow be causing this temporarily?

A plugged fuel vapor recovery system can cause a slight vacuum in the tank, but not pressure.

There was a little moisture in one of the cannister lines when I disconnected it, but it was not gas

Usually a sign that the tank fuel filler rim rainwater drain line and the tank's internal vent line have been connected backward.

Is there a right and wrong way to connect the fuel lines?

Yes, but the bike won't run it the fuel pressure lines are backward.

[kiwiaudio]

Thanks Ken, you've cleared up a few things for me.

 

Quote:

" Usually a sign that the tank fuel filler rim rainwater drain line and the tank's internal vent line have been connected backward. "

 

Is there a hole around the filler neck that is the rainwater drain? If so, then I can blow through this line to determine which is which ? This filler drain line is the one that will go directly to behind the right footpeg then ?

[Stan Walker]

Is there a hole around the filler neck that is the rainwater drain? If so, then I can blow through this line to determine which is which ? This filler drain line is the one that will go directly to behind the right footpeg then ?

 

Yes, yes, and yes.

 

Stan

[kiwiaudio]

Thanks Stan !

[T__]

Mark, the fuel pressure is not higher on cold start as the 1150 doesn’t use an externally controlled pressure regulator..

 

 

I find it difficult to believe you have a leak at the wire pass through or wiring area.. That is a non-pressurized area so you would think it would leak there whether or not it is running or the pump was operating.. It sounds like your leak only shows up with the engine (therefore fuel pump) running?. You would think that would point to a leak in the pressure side of the system..

 

It could be possible to have a very small pin hole leak where the pressure side hose clamps to the outlet fitting & possibly spraying a fine stream of fuel on the wire area (maybe)..

 

You might try spraying the entire tank outlet area including hoses with foot spray powder (will help to find the leak origin) then hooking a My-Ty-Vac (or similar vacuum/pressure pump) to the tank vent.. First try pulling a vacuum then allow it to bleed off as you run the fuel pump & engine.. Then try pressure in the tank through the vent line then run the fuel pump & engine.. It’s possible you have a hose that unseats slightly from vacuum while sitting then leaks for a second or two as the tanks goes positive pressure.. Or even a hose ply separation allowing a small fuel spray out the end plys of the hose at first run up..

 

Another approach would be to pull the tank,, drain the tank of fuel,, plug the hoses (or allow the quick disconnects to do their job).. Then lightly pressurize the tank with compressed air (not too much or you could rupture the tank) then submerge it in water & look for air bubbles.. Air will leak out easier than fuel as it is less dense.. Or pressurize the tank with Freon & use an AC leak detector & sniff for leakage at the hoses & wire pass through..

 

You best find that leak before you have a fire..

 

Twisty

[kiwiaudio]

Thanks for your ideas Bill.

The leak most definitely is on the pressure side of the system as it quit pouring out immediately on shutdown. There was so much fuel coming out I expected to find a hose off completely!

I have to believe it was the pressured hose at the pump plate squirting out at the wires which have a loosely fitting black plastic outer tube. When I pulled the tank, gas came out of this wiring harness tube and nowhere else. Neither the pressure hose or the return hose were extremely tight as both could be turned on their fittings.

I inspected everything in that area and thats all I could find. I could not replicate the leak situation again either, even five mins later!

 

Double FI clamps everywhere for this kid !!

 

I have the tank hooked up off the bike, and I'm going to leave it this way for a while, starting it and testing things until I'm convinced it will not leak again.

I cannot have fuel even dripping down onto my header pipes - Aside from the obvious reason, its Three bucks a gallon !