1977 gs750 fuel coming out of crank case vent tube

[Nessism]

If the petcock is allowing fuel to flow when set on the Res and On positions, and the engine is not running, that is a problem. Basically your petcock is not doing anything to stop fuel from flowing when the engine is off, thus the float needles are the only thing that is keeping your carbs from overflowing and flooding the crankcase with fuel. Most likely you have a ton of gas in the oil already.

As mike says, the vacuum line should run to the #3 carb (third from left). I don't understand how the vacuum line can T into the fuel line since the tube diameters are significantly different. Some photos would be useful to allow us to understand.

Honestly here, I don't even want to think about this situation any longer and I suggest you don't either. Pull the carbs and go though them fully. Perform a full rebuild using the tutorial on the GSR Homepage (in the Garage tab) and replace the O-rings with a kit from cycleorings.com. Replace the intake boot O-rings. Get new fuel and vacuum lines from a dealership source. Rebuild your petcock or get a new one. Z1 Enterprises sells kits.

And download a factory service manual from either repairmanualclub.com or basscliff's web site.

You can't diagnose a bike with all these monkey rigged parts and unknown condition carbs. Needless to say the gas tank should be clean and free of rust too.

Once you do some of this basic maintenance, they you can try to diagnose problems, if there are any left.

[BassCliff]

Greetings and Salutations!!

Hi Mr. hdcrossbones09,

Your bike is suffering from "30 years old and nobody has taken care of me for a long time"-itis. There are several things you should do, up front, to get your bike back to its former glory. These steps are outlined in the links below. Take no shortcuts and your bike will love you.

Anyway, let me dump a TON if information on you and share some GS lovin'.

I just stopped by to welcome you to the forum in my own, special way.

If there's anything you'd like to know about the Suzuki GS model bikes, and most others actually, you've come to the right place. There's a lot of knowledge and experience here in the community. Come on in and let me say "HOoooowwwDY!"....

Here is your very own magical, mystical, mythical, mind-expanding "mega-welcome". Please take notice of the "Top 10 Common Issues", "Top 15 Tips For GS Happiness", the Carb Rebuild Series, and the Stator Papers. All of these tasks must be addressed in order to have a safe, reliable machine. Now let me roll out the welcome mat for you...



Please click here for your mega-welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!

Thanks for joining us. Keep us informed.

Thank you for your indulgence,

BassCliff

[hdcrossbones09]

maybe this will help you guy help me sort this problem out thanks sooooo much

[hdcrossbones09]

wish i could upload more than 1 at a time

[hdcrossbones09]

post whore

[mike_of_bbg]

You can attach more than one image to a message, they just have to be hosted elsewhere and linked into your post.

[hdcrossbones09]

last 1 unless someone needs something specific sorry thanks

[mike_of_bbg]

last 1 unless someone needs something specific sorry thanks

Yeah that last picture they have the vacuum and fuel ports on the petcock teed together. That is wrong. It should not flow fuel except on "PRI", and if it does the petcock diaphragm is shot and you're getting fuel through the vacuum tee (effectively you're always flowing fuel as on PRI). The needle valves in the carbs are not meant to hold back a constant steady pressure of fuel when not in operation, and are leaking and overflowing into your airbox.

The idea is that the petcock should not flow fuel in the ON position unless the diaphragm is getting vacuum (because the engine is running) via the vacuum port on carb #3 (that's carb #2 BTW on the 80-82 CV carbs, not that you care).

The vacuum port should be connected to the hose coming off of #3 carb. The hoses from #2 and #4 are vent hoses and the ends should be left in a relatively turbulence-free area. Where is the hose from #3 leading now? I hope it is at least plugged.

OEM replacement petcocks still appear to be available for $75-$100.

[chuck hahn]

Call me immmediately i PMed you my number..

[Big T]

Go back and read thru BassCliffs site on posting pictures and repairs, especially the 10 things


That's one seriously messed up bike, I wonder what else the PO did that's just completely wrong?

Get some new fuel line from the T to the petcock, run the hose on #3 to the petcock and see what happens

Have you checked your oil level? Does your oil smell like gas?

[BassCliff]

Hi,

Have a look at this:

Where Do These Hoses Go?

Your carbs are the VM style so the vacuum port on the petcock will attach to the #3 carb, to a nipple on the top/rear of the carb (not the #2 like on the CV style carbs). Each of your carbs will have a drain hose. The fuel line runs to the "T" between the #2 and #3 carbs.

I'll bet there's gas in your oil. You'd better change it.


Thank you for your indulgence,

BassCliff

[hdcrossbones09]

I can't find the vacuum port between the carbs that runs to the petcock

[chuck hahn]

ON the LEFT side of carb 3 sticks out at an angle just above and to the right of the fuel tee in the center..... kinda in the middle of the carb body.

[Big T]

Right next to the fuel T