Intermittent fuel leak

[Anonymous]

I found there is an intermittent fuel leak on my 1980 GS1100E. After running the bike for maybe 20 kilometers (about 12 miles), there will be gas dripping on the left side exhaust just below the gear mechanism and also running along the bottom of the left side of the swingarm.

The first time I saw this, I was in the middle of nowhere so I rode home at brisk pace (have fire extinguisher there). The leak was minor at this point and stopped before I could find where the gas was coming from.

Today, I installed new gas line from tank to filter to as one piece looked suspect. I check for gas at about 5 K, all OK. At 20 K, gas was leaking again. It stopped shortly after I got off the bike. It was not leaking when I got home shortly after that.

Any ideas on what could be causing this?

Patrick


It will not leak when warming up or for the first few Ks. It seems to stop leaking when engine shut down. It does not leak continually.

I mounted tank remotely this afternoon and tried to find the leak. No luck. I am thinking the leak is caused by the expansion of something when the engine first warms up.

[Anonymous]

When my stock fuel petcock began leaking internally (holed diaphram allowing fuel to be pulled into number two intake via the vacuum line) I was getting raw fuel coming out the number two exhaust. Raw fuel was blowing out the seam where the exhaust pipe meets the muffler assembly under the left side of the engine. That might be the source of the fuel you're finding? To test for this condition, I thoroughly pinched off the vacuum line between the petcock and the number two intake (I used locking needlenose pliers) then started and rode the bike with the petcock on prime - no more flooding. The petcock can be rebuilt (parts $20 US), replaced with OEM or pattern part ($60 to $90 US), or replaced with Pingel or other aftermarket petcock. I chose a new Suzuki part and I expect another 21 years service out of it. This bad diaphram problem is extremely common. Good luck.

[Anonymous]

fuel leak

Al

Thanks for the advice. I will try to check this when the rain stops (he says jokingly). One thing I was thinking last night is that it might be my in-line fuel filter acting up. It is made from a rigid clear plastic and I suspected that the heat cycling may have caused the seams to leak at times (I have a new one-piece opaque filter that will replace the suspect unit - again, when the rain stops).

Thanks again for the suggestion.

Patrick

ps Did you get the new petcock from a local dealer or from the US?

[Jay B]

Sounds like gas may be getting into the carb vent tube. They vent back in that area.

[Anonymous]

I had a similar problem and I will have to agree with patrikobrien. I replaced the petcock and no more leak. I also have a similar filter as what you are describing(clear). This was on my 850.

[Anonymous]

Hi Jay: I have the two over-flow lines routed back above the side covers together with the tank vent line. I had wrapped them in towel to find any evidence of fuel venting from them (they were all clean). They were one of the first things I thought of too. Please let me know if you are referring to another line.

Hi Tankman: Thanks for the input. Did you ever find a problem with the hard plastic filter leaking?

The intermittent nature of the leak kind of puzzles me. I hope to get at it tomorrow (rain or shine, cause winter is coming soon).

Thanks for the feedback. It is much appreciated.

Patrick

[Anonymous]

pennzoil

I found gas in the suction line from the petcock when I installed a loop of clear Nalgene tubing in the circuit. I checked the petcock diaphram material and it looked in good shape. I put it on prime and blocked off the suction line.

I also replaced the fuel filter with a one-piece opaque unit as I suspected gas was leaking from the rigid plastic two piece filter I installed last year.

Gas was still leaking today when I took the bike out for a 20K ride (I wanted to duplicate the condition where I found the leak before). The amount of fuel leaking appeared to be less.

One thing I had done prior to the fuel leak showing up was to add a gas additive made by Pennzoil intended for fuel system cleanup. This may have been a case of my curiosity getting the better of me.

I drained the remaining fuel and replaced with fresh gas tonight. I may get the chance to take those carbs off again if the leak continues.

Thanks again for the advice in trying to track the cause of this down.


Patrick