Author Topic: Carb sync question (Read 2594 times)

Airmotive · « **on:** August 27, 2005, 12:25:49 AM »

Okay, so I've gotten my little $1.50 carb sunc tool all set up. (20 feet of clear tubing looped over the garage door track), and hooked it up to my 1 and 2 carbs.

I removed my fuel tank and ran a tube from the fuel tank to the carbs (actually, to the fuel filter).

I put the fuel petcock on "prime"...no fuel flow.

I put the petcock on "res" and hook the little vacuum tube up to the #4 carb. Crank the engine...it fires up and runs on the residual fuel in the carb bowles....still no fuel flow from the tank. Eventually the engine dies.
I pull the line off the tank...it seems to be under pressure (the line, not the tank). WTF?

The engine has no fuel issues when the tank is hooked up normally...all I did was add an extra 4 feet of tubing between the tank and the fuel filter (and yes, the tank was elevated, no line kinks). The fact that the tube was under pressure has me baffled. As soon as I pulled this fuel line off the tank, gas poured from the petcock. Am I missing some basic fuel system operations here?

BTW...for the 20 seconds the engine was running, I was able to determine that my #1 carb was pulling decidedly more than my #2 carb. I didn't have time to make any adjustments before the engine died, however.

Suggestions?

Blue Skies,
JJ

Red01 · « **Reply #1 on:** August 27, 2005, 12:57:57 AM »

That's strange!

The fuel system is just a basic gravity flow system. the only complexity to it is the vacuum operated petcock, and in PRI, that should be eliminated.

Obviously, if you have the vacuum line off the petcock, you need to plug that source when it isn't hooked up to the tool.

Seems like the only other thing that could go wrong is an obstruction of some kind in the fuel supply hose.

Airmotive · « **Reply #2 on:** August 27, 2005, 02:17:15 AM »

Well....we're all done now. In stead of mounting the fuel tank remotely, I just turned the tank sideways and left it sit...all hooked up but out of my way.

Hooked up my JJ's Tunin'Tube and easliy synched 1 to 2. Then 3 to 4 and finally 2 to 3. Easy as pie.

I suppose i could break out my engineering books and figured out the significance of a pressure difference of 5 inches of water....but I dont care. I turned back to where there was no difference and moved on to the next set.

Got pictures, too. Just have to find a way to post them.

Blue Skies,
JJ

Red01 · « **Reply #3 on:** August 29, 2005, 08:05:09 PM »

Quote from: "Airmotive"

Got pictures, too. Just have to find a way to post them.

Read this thread.