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Fuel Leak

Pete Wrigley

Pete Wrigley

Forum Apprentice
Past Site Supporter
My 1980 GS750L started leaking fuel. I walked out into garage and there was a puddle of fuel on the floor. It appeared to be leaking from the ignition cover. Without doing an extensive inspection I believe the fuel is leaking from the carb bowls. I had notice a small leak from them last month after a very short ride around the block. The bike is new to me and I was told the carburetors had been rebuilt. I'm thinking the petcock is not doing its job and allowing fuel down into the carbs, it overflows, finds it's way down to the ignition cover and drips out the weep hole in the bottom. Bike is on it's center stand. I placed a pan underneath to catch drips. I welcome any thoughts on this. :smug:
 
For one thing, make sure your petcock shuts off the flow of fuel when the engine is turned off. And don't leave your petcock on the prime position.

Secondly, needless to say you need to pinpoint the source of leakage. The most common reason is because of a blocked or worn out float valve in one or more of the carbs. There is a carb rebuild tutorial linked in my signature which may help you.

Lastly, never trust anything the previous owner says about the maintenance status of your bike. Learn for yourself.
 
You didnt leave the petcock in PRIme position did you?
If so, that is your problem.

THe carb float needles cant be expected to complelty shut off gas flow, so the auto petcock provides that function (but cant if you leave in PRIme position).
Pull/pry the big line off the petcock, see if the petcock is shutting completly off.

Other concern: Might now be gas in your crankcase oil.

>>Later note:
Oh, an L.
Some of those petcocks dont have a lever. . . . . not sure which do or dont.
 
Last edited:
Yes, an "L" with no lever. vertical slot=Prime, horizontal =Run. yes? if so... then I was in prime. I set it to run using a very narrow flathead screwdriver. The bike is in for the winter and I plan on replacing all fluids before riding next year.
 
Still can't imagine anybody would ever design such a (don't want to say STUPID but can't think of a better word) pet cock. Mine had the PRI kind'f at a diagonal location, neither vertical nor horizontal, just had to guess at it. Thankfully it only lasted a yr. or so.
 
Pete Wrigley said:
Yup, That's it.
Click to expand...

The service manual describes how that petcock functions.

With the slot in the prime position a pulse of vacuum from the engine pulls the internal diaphragm open, and a check valve holds it open until the slot is turned back to the run position.
 
Last edited:
This forum is so great. I appreciate all the help guys. From the little I've read so far the reason for this type of petcock has something to do with the bike having a fuel gauge. I'm not sure of all the technical detail behind it. Can I just leave it in the "run" position?
 
Nessism said:
The service manual describes how that petcock functions.

With the slot in the prime position a pulse of vacuum from the engine pulls the internal diaphragm open, and a check valve holds it open until the slot is turned back to the run position.
Click to expand...


That's interesting. I would have figured it to operate the same as others. Turn to PRIme and fuel flows. I'd be the one to try and prime the bowls while putting my gear on and then hit the start button. This makes me even more thankful for the later model G design.




Pete Wrigley said:
This forum is so great. I appreciate all the help guys. From the little I've read so far the reason for this type of petcock has something to do with the bike having a fuel gauge. I'm not sure of all the technical detail behind it. Can I just leave it in the "run" position?
Click to expand...

Redman said:
You didnt leave the petcock in PRIme position did you?
If so, that is your problem.

THe carb float needles cant be expected to complelty shut off gas flow, so the auto petcock provides that function (but cant if you leave in PRIme position).
Pull/pry the big line off the petcock, see if the petcock is shutting completly off.

Other concern: Might now be gas in your crankcase oil.

>>Later note:
Oh, an L.
Some of those petcocks dont have a lever. . . . . not sure which do or dont.
Click to expand...
 
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