carb leak, vacuum port???

zach0 · 10-31-2001, 05:30 PM

Strange, I had gas coming through my lower vacuum port for my pcv valve. adjusted fuel bowl down and it seems to have stopped. Is there a bigger problem?? Brand new carb holley 6something cfm. Rear vacuum port behind the chocke.

PKRWUD · 10-31-2001, 06:49 PM

Your secondary float level was too high, or your secondary needle and seat were stuck open. Probably the float. Either case would permit too much fuel to enter the secondary bowl, raising the level higher than the boosters in the secondaries. By gravity, this would force the extra fuel to trickle out of the boosters and down to the secondary throttle plates, where it would seep by the throttle plates and into the engine, causing a rough, "jumpy" idle and a rich condition. The vacuum port you are referring to gets it's vacuum from directly underneath the secondary throttle plates, which would make access to that hose by the excess fuel pretty direct. The only thing is, there should be vacuum sucking everything OUT of that hose, not into it. Now, when you initially punch the gas, your vacuum will drop to zero, allowing the fuel to enter the hose, but that should reverse it's direction as soon as you back off the throttle and create vacuum again. The only way that wouldn't suck the fuel from the hose is if the hose is either plugged (clogged or installed backwards PCV valve) or you don't have a source for air to enter the crankcase to equalize the PCV system. Lowering the float level will prevent the gas from entering the line, but you still have a problem with your PCV system. Tell me how all the hoses are routed.

Take care,
-Chris

------------------
Retired Moderator
MustangNet

My site: Peckerwoods Pit Stop

My teams site: Jim Porter Racing

RACECAR spelled backwards is RACECAR

HEY !!! Are you ASE Certified ??? If you are, ask me about iATN.

10-31-2001, 05:30 PM	#1
zach0 Registered Member Join Date: Apr 2001 Location: Hampton, Virginia Posts: 227	carb leak, vacuum port??? Strange, I had gas coming through my lower vacuum port for my pcv valve. adjusted fuel bowl down and it seems to have stopped. Is there a bigger problem?? Brand new carb holley 6something cfm. Rear vacuum port behind the chocke.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Vacuum leak??	daccrow86	Classic Mustangs	4	10-20-2003 10:25 AM
Can't Find Vacuum (or some kind of) leak	Rog5.0	Windsor Power	1	04-13-2003 10:57 PM
tricks to find vacuum leak	fiveohpatrol	Windsor Power	5	10-03-2002 06:15 PM
Vacuum Leak After Transmission Rebuild	diablopony	Classic Mustangs	4	06-17-2001 07:15 PM
carb guys vacuum??	89LXCarb	Windsor Power	3	02-09-2001 01:26 PM

10-31-2001, 06:49 PM	#2
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	Your secondary float level was too high, or your secondary needle and seat were stuck open. Probably the float. Either case would permit too much fuel to enter the secondary bowl, raising the level higher than the boosters in the secondaries. By gravity, this would force the extra fuel to trickle out of the boosters and down to the secondary throttle plates, where it would seep by the throttle plates and into the engine, causing a rough, "jumpy" idle and a rich condition. The vacuum port you are referring to gets it's vacuum from directly underneath the secondary throttle plates, which would make access to that hose by the excess fuel pretty direct. The only thing is, there should be vacuum sucking everything OUT of that hose, not into it. Now, when you initially punch the gas, your vacuum will drop to zero, allowing the fuel to enter the hose, but that should reverse it's direction as soon as you back off the throttle and create vacuum again. The only way that wouldn't suck the fuel from the hose is if the hose is either plugged (clogged or installed backwards PCV valve) or you don't have a source for air to enter the crankcase to equalize the PCV system. Lowering the float level will prevent the gas from entering the line, but you still have a problem with your PCV system. Tell me how all the hoses are routed. Take care, -Chris ------------------ Retired Moderator MustangNet My site: Peckerwoods Pit Stop My teams site: Jim Porter Racing RACECAR spelled backwards is RACECAR HEY !!! Are you ASE Certified ??? If you are, ask me about iATN.