PETCOCK QUESTION

[Guest]

WHERE DOE THE VACUUM HOSE OFF THE PETCOCK CONNECT TO. I HAVE A 79 GS 750L BUT WITH A 77 TANK. THERE'S NO FUEL GAUGE. DOES IT GO THE CARBS OR SOMETHING?

[Anonymous]

My experience with an 82 gs850 is vac line from tank goes between #1 & #2 carb. The petcock should have 2 settings, one is pri which doesn't need the vaccume line to flow.

mike

[Ghostgs1]

On my 78 GS1000E, the vacuum comes from the #3 carb. Located at the rear, upper left hand side of the carb. The #2 & #4 carbs have vent lines located in a similar location. My carbs are VM-26"s. Good Riding.

[SqDancerLynn1]

79 is a different animal. You have the VM slide carbs The vacuum hose connection goes to the # 3 carb. Carb # 2&4 are vents

[Anonymous]

sorry about that ... brain fart! it's ok now. Thanks for clearing up the issue!


mike

[Tarbash 27]

OK I HOOKED UP THE VACUUM HOSE FROM THE PETCOCK TO NUMBER 3 CARB. AND IT WORKS. BUT TODAY MY BIKE WAS HESITATING ALOT AND DIDN'T WANT TO MOVE. I NOTICED THAT WHEN THE VACUUM HOSE IS DISCONNECTED, MY BIKE RUNS BETTER, IT IDLES HIGHER, BUT IT HAS A KNOCKING SOUND AND IOT ONLY RUNS ON PRIME. I HAVE IT HOOKED UP THE CORRECT WAY AND THE BIKE IDLES LOWER, DOESN'T KNOCK, AND HESITATES ALOT. IS THERE SOMETHING WRONG WITH THE CARBURETOR OR PETCOCK? I THINK ITS ALSO RUNNING RICHER BECAUSE I CHECKED THE PLUGS AND THEY ARE BLACK. BEFORE I HAD THE VACUUM HOSE HOOKED UP, THEY LOOKED LEAN, DRY REDISH/WHITEISH. WHAT DO I DO?

[Anonymous]

What to do...

#1. Realize that on the net, all-caps means you're SCREAMING.

#2. Pull the vacuum line of the petcock and check for gasoline. Use a syringe and pull a vacuum and see if fuel comes out. Or, if you're really brave and don't mind a mouth full of gas, suck on it. If gas comes out, your petcock diaphram is bad.

#3. Use Search (top of this page, 2nd icon in the list). Type in "petcock and diaphram and leak" without the quotes and read about many others that have had this problem.

My bet is the diaphram is blown. One of the functions of the petcock valve is to stop fuel flow to the carburetors when the engine isn't running. This is desireable because you never want to gravity feed fuel from the tank into the engine when it isn't running. It accomplishes this by use of a vacuum controlled valve built into the petcock body. When the engine is running the vacuum opens the valve and fuel flows. In your case, the diaphram is probably broken and fuel is flowing into the vacuum line flooding the engine and blackening your plugs.

[rustybronco]

Don't know if i can help but did you check to see if there is fuel comeing out of the vacuum port of your petcock? with the petcock not in the prime position hook a hose to the petcock vacuum port and put it into a container, if it leaks... more fuel to the engine and richer looking plugs...there may be other issues but this is all I can offer, hope it helps.

[Tarbash 27]

GAS DOES NOT COME OUT OF THE VACUUM HOSE. WELL I DIDN'T SUCK ON IT LIKE THE OTHER GUY SAID. I HAVE ANOTHER TANK AND I AM GOING TO SWAP OUT PETCOCKS AND SEE WHAT HAPPENS.

[gspaul]

If you use a clear vacumn hose you can see if gas is being sucked through it!

[Tarbash 27]

OK, I GOT THE BIKE TO RUN OK. BUT ONCE AND A WHILE IT WILL HESITATE AND NOT WANT TO MOVE. BUT 90% OF THE TIME IT RUNS FINE

[pasteurized]

Hey Tarbash, you want to do us all a favor and turn off your caps?