Vapor lock 6-pack question/solution

Jeff Erwin

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440 6-pack 71 Charger with the expected vapor lock issue. The solution is to install a fuel-vapor separator, which I purchased a few weeks ago, to replace the fuel filter. I was going to run a fuel line from the return tube of the vapor separator back to the tank, replace the sender unit in the tank with one that has the extra nipple specifically for this. However I noticed that the vapor vent in the center carb attaches to a fuel line that then disappeared under the car. I asked about it here a few weeks and was told it probably just vents onto the ground.
IMG_6502.JPG

I got the car onto my lift today and discovered that the carb vent line goes all the way back to the vapor saver next to the fuel tank. Fine, I suppose the vapor savor is there for that exact reason.
IMG_6501.JPG

IMG_6503.JPG

My question is this: can I just connect the return tube of the vapor separator to this line that would then return said vapor to the 'vapor saver' or do I really have to run a separate fuel line back to the sender to get the vapor lock vapor back into the tank? I have no idea how much 'vapor' is created in the typical vapor lock situation with these engines, but I have to think it isn't a ton. Seems like the vapor savor could handle this fine, but I don't want to be stupid when gas is involved.

Related question about the carb vapor vent. I have seen a few setups where this line is fed into the valve cover along with the fresh air line for the pcv system . Is this an acceptable practice? I am envisioning the engine vacuum sucking fuel out of the center carb for some reason.
 

R413

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No you cannot, it is for vapor. The line out of the separator will have constant liquid fuel anytime the engine is running,
 
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1rustedrt

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had vapor locking on my six pack set up tried the separator and did not help, unleaded will boil out at a lower temp than leaded fuel tried several things, aluminum radiator, thermal spacer, 160 thermostat, high volume water pump , and some other things. the only thing i found that worked was high output 4000 cfm electric fans to cool the engine down and the engine compartment to get the heat out!!! haven't vapor locked since putting in the fans. used flex alite 295 fans. good luck
 

Sixpactogo

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440 6-pack 71 Charger with the expected vapor lock issue. The solution is to install a fuel-vapor separator, which I purchased a few weeks ago, to replace the fuel filter. I was going to run a fuel line from the return tube of the vapor separator back to the tank, replace the sender unit in the tank with one that has the extra nipple specifically for this. However I noticed that the vapor vent in the center carb attaches to a fuel line that then disappeared under the car. I asked about it here a few weeks and was told it probably just vents onto the ground.
View attachment 1286409
I got the car onto my lift today and discovered that the carb vent line goes all the way back to the vapor saver next to the fuel tank. Fine, I suppose the vapor savor is there for that exact reason.
View attachment 1286410
View attachment 1286411
My question is this: can I just connect the return tube of the vapor separator to this line that would then return said vapor to the 'vapor saver' or do I really have to run a separate fuel line back to the sender to get the vapor lock vapor back into the tank? I have no idea how much 'vapor' is created in the typical vapor lock situation with these engines, but I have to think it isn't a ton. Seems like the vapor savor could handle this fine, but I don't want to be stupid when gas is involved.

Related question about the carb vapor vent. I have seen a few setups where this line is fed into the valve cover along with the fresh air line for the pcv system . Is this an acceptable practice? I am envisioning the engine vacuum sucking fuel out of the center carb for some reason.
That vent on the center carb should be hooked to the breather cap as shown in this pic. I've seen a lot of them not hooked to anything at all.

440 Six pack.JPG
 

R413

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The bowl vent hose on the center carb bowl originally did go to the breather cap and than the vapor line was hooked to the breather also. It is to catch the vapors for emissions. That vent can be left open if you want.

Ethanol free gas will help this problem greatly.
 

440 PHIXX

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I put an electric fuel pump on both my 440 Six Pack engines. I used it with the Carter mechanical as per the DC manual. Never a problem. Mine are 1970, so the bowl vent goes to the atmosphere, and the return line goes into the tank.
 

72RoadrunnerGTX

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Reviewing your previous description, are you sure it’s a fuel line vapor lock issue? Have you tried a heat soak start with the air cleaner removed? The fuel tank vent line from the fuel tank separator you indicated is connected directly the center carb enclosed bowl vent valve nipple could simply be flooding the air cleaner with fuel tank vapor, with the three bowls contributing, would make for a very over-rich hot start condition.

As mentioned, for a correctly plumed ’71 evaporative recovery system, both the bowl vent line and the fuel tank line need to be plumbed to their correct nipple on the 3-nipple breather cap. Designed to have these at rest fuel vapors collected/stored in the crankcase for later purging through the PCV on start-up.


’71 V-code should have had a ¼” return hardline from the factory, along with the 3’/8’ fuel and the 5/16” tank vent line, it was removed?
Fuel lines2.jpg
 
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davek

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its the gas,I had to siphon some gas out of the tank and got a mouth full and it didnt even phase me. Gas today is CRAP.
 

Carcinogen

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Usually the problem is the mechanical fuel pump getting hot, try eliminating it and going with electric pump along with pressure regulator with fuel return so fuel don't dead head and build heat.
 

Jeff Erwin

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Reviewing your previous description, are you sure it’s a fuel line vapor lock issue? Have you tried a heat soak start with the air cleaner removed? The fuel tank vent line from the fuel tank separator you indicated is connected directly the center carb enclosed bowl vent valve nipple could simply be flooding the air cleaner with fuel tank vapor, with the three bowls contributing, would make for a very over-rich hot start condition.

As mentioned, for a correctly plumed ’71 evaporative recovery system, both the bowl vent line and the fuel tank line need to be plumbed to their correct nipple on the 3-nipple breather cap. Designed to have these at rest fuel vapors collected/stored in the crankcase for later purging through the PCV on start-up.


’71 V-code should have had a ¼” return hardline from the factory, along with the 3’/8’ fuel and the 5/16” tank vent line, it was removed?
View attachment 1286573
Sadly the car wasn't an original V code, engine was swapped in the 90's. Originally a 383.
 

Jeff Erwin

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Reviewing your previous description, are you sure it’s a fuel line vapor lock issue? Have you tried a heat soak start with the air cleaner removed? The fuel tank vent line from the fuel tank separator you indicated is connected directly the center carb enclosed bowl vent valve nipple could simply be flooding the air cleaner with fuel tank vapor, with the three bowls contributing, would make for a very over-rich hot start condition.

As mentioned, for a correctly plumed ’71 evaporative recovery system, both the bowl vent line and the fuel tank line need to be plumbed to their correct nipple on the 3-nipple breather cap. Designed to have these at rest fuel vapors collected/stored in the crankcase for later purging through the PCV on start-up.


’71 V-code should have had a ¼” return hardline from the factory, along with the 3’/8’ fuel and the 5/16” tank vent line, it was removed?
View attachment 1286573
Pretty sure it's a vapor lock issue. The engine will start after a heat soak , I suspect using the gas in the bowl as it will run for about 30 seconds then die. Hard crank start after that, then runs fine.
 

Jeff Erwin

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Reviewing your previous description, are you sure it’s a fuel line vapor lock issue? Have you tried a heat soak start with the air cleaner removed? The fuel tank vent line from the fuel tank separator you indicated is connected directly the center carb enclosed bowl vent valve nipple could simply be flooding the air cleaner with fuel tank vapor, with the three bowls contributing, would make for a very over-rich hot start condition.

As mentioned, for a correctly plumed ’71 evaporative recovery system, both the bowl vent line and the fuel tank line need to be plumbed to their correct nipple on the 3-nipple breather cap. Designed to have these at rest fuel vapors collected/stored in the crankcase for later purging through the PCV on start-up.


’71 V-code should have had a ¼” return hardline from the factory, along with the 3’/8’ fuel and the 5/16” tank vent line, it was removed?
View attachment 1286573
What is this diagram from?
 

6PKRTSE

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Not sure why you guys are having vapor lock issues. My sixpack car has no separator on it and I have never had any vapor lock issues with it when driving in the 32 years I have owned it. Even after idling for hours in Woodward Dream Cruise or Telegraph cruise traffic here in the Motor City. The only time that I have had vapor lock type issues is when my fuel pump push rods wore out enough that they were too short and pumping enough fuel on a couple of other cars I once owned.
 

Jeff Erwin

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Not sure why you guys are having vapor lock issues. My sixpack car has no separator on it and I have never had any vapor lock issues with it when driving in the 32 years I have owned it. Even after idling for hours in Woodward Dream Cruise or Telegraph cruise traffic here in the Motor City. The only time that I have had vapor lock type issues is when my fuel pump push rods wore out enough that they were too short and pumping enough fuel on a couple of other cars I once owned.

Lucky maybe? I know the 440 6-pack V code cars had a vapor separator and return line to the tank installed at the factory so there must have been an issue with that specific configuration. Is your car a factory 440 6-pack? Year? I would be interested in knowing why there isn't a return line if it is. My Charger isn't an original 440 6-pack so it doesn't have the 3rd fuel line (fuel, vapor from the center carb to the vapor tank next to the gas tank and line from the vapor separator back to the fuel sender).
 

72RoadrunnerGTX

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(fuel, vapor from the center carb to the vapor tank next to the gas tank and line from the vapor separator back to the fuel sender).
To be clear, for the federal ’71 and California ’70-71 ECS system, the fuel tank vent line in not intended to be directly connected the enclosed fuel bowl vent valve nipple. Both of these vent lines are connected to the 3-nipple breather cap.
 

6PKRTSE

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To be clear, for the federal ’71 and California ’70-71 ECS system, the fuel tank vent line in not intended to be directly connected the enclosed fuel bowl vent valve nipple. Both of these vent lines are connected to the 3-nipple breather cap.
One of my 70 Charger's is a factory California "so called" emissions car and it is all still on the car with the 3 nipple breather.

100_1698.jpg
 

Jeff Erwin

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To be clear, for the federal ’71 and California ’70-71 ECS system, the fuel tank vent line in not intended to be directly connected the enclosed fuel bowl vent valve nipple. Both of these vent lines are connected to the 3-nipple breather cap.

Yeah, I'm in the process of fixing that now. When done the 3-nipple cap will have the fuel bowl vent from the center carb, the line from the vapor canister next to the fuel tank and the air line from the air filter. Right now it's all messed up, the carb vent line is going to the vapor canister. Not sure if all this will affect performance.
 

72RoadrunnerGTX

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A correctly plumed and intact ECS system will not have any detrimental effects on performance. The ’71-early ’72 fuel tank vapor separator tended to be prone to pin holes from rust as a result from its location in the left rear wheel well, would leak fuel and/or fuel vapors.

As mentioned, with the fuel tank vapor separator directly plumbed to the fuel bowl vent valve, I would expect high levels of fuel vapors collecting in the air cleaner at rest and hot start issues.
 

Jeff Erwin

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A correctly plumed and intact ECS system will not have any detrimental effects on performance. The ’71-early ’72 fuel tank vapor separator tended to be prone to pin holes from rust as a result from its location in the left rear wheel well, would leak fuel and/or fuel vapors.

As mentioned, with the fuel tank vapor separator directly plumbed to the fuel bowl vent valve, I would expect high levels of fuel vapors collecting in the air cleaner at rest and hot start issues.

Well, that might explain the loud POP when I turn the engine off after driving and the hot start issues...
I can't figure out what the people that worked on this engine before my ownership were thinking plumbing the output of the vapor separator to the output of the float bowl. Both want a mild vacuum to pull vapors, connecting them together doesn't make sense. All parts ordered to fix this, have to run a vapor return line from the new vapor separator back to the tank and put a 3-nipple valve cover vent in.

You're in Shoreline. I'm out in Woodinville. You going to the big Duval car show next weekend?
 

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