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Re: Fuel Pressure Regulator w/ Return to Help Vapor Lock
[Re: Cab_Burge]
#1628244
06/04/14 07:54 PM
06/04/14 07:54 PM
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Joined: Jan 2003
Posts: 16,376
dogdays
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,376
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Some of the confusion is due to incorrect terminology.
The VAPOR SEPARATOR is to keep vapor out of the carburetor. That's what the filter with the extra fitting is for. I believe that if one looks up into the smaller tube coming off the filter, one sees a smaller hole (orifice) where the tube connects to the filter body. The return line conducts the vapor and whatever liquid fuel flowing through the orifice, back into the fuel tank. Otherwise, where would it go?
Now on to the back of the car. In 1971, maybe earlier, Federal regulations required new cars to control emissions of fuel evaporating from the gas tank. This is called EVAPORATIVE EMISSIONS CONTROL. It controls evaporative emissions by collecting the vapor that exists in the top of the tank and catching it in either a larger container where the evaporated fuel can condense and run back into the tank, or else into a charcoal canister that is plumbed to the engine intake, so that the evaporated fuel is eventually burned by the engine. This had NOTHING to do with preventing vapor lock, and was not primarily intended to allow the complete filling of the tank. It was a response to a Federal mandate.
My 1972 Nova had the charcoal canister. My 1971 D100 had a simple vent line going to a larger segment of tube, which I think had an overflow that went through the floor.
Starting whenever the Federal mandate went into effect, gas caps were NO LONGER VENTED.
There is nothing about the evaporative emissions control system that harms performance. (Well, maybe it adds a pound or two of extra weight.) Removing it only demonstrates one's ignorance.
R.
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Re: Fuel Pressure Regulator w/ Return to Help Vapor Lock
[Re: dogdays]
#1628245
06/04/14 10:05 PM
06/04/14 10:05 PM
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Joined: Jan 2007
Posts: 7,664
IN
ahy
master
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master
Joined: Jan 2007
Posts: 7,664
IN
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Quote:
Some of the confusion is due to incorrect terminology.
The VAPOR SEPARATOR is to keep vapor out of the carburetor. That's what the filter with the extra fitting is for. I believe that if one looks up into the smaller tube coming off the filter, one sees a smaller hole (orifice) where the tube connects to the filter body. The return line conducts the vapor and whatever liquid fuel flowing through the orifice, back into the fuel tank. Otherwise, where would it go?
Now on to the back of the car. In 1971, maybe earlier, Federal regulations required new cars to control emissions of fuel evaporating from the gas tank. This is called EVAPORATIVE EMISSIONS CONTROL. It controls evaporative emissions by collecting the vapor that exists in the top of the tank and catching it in either a larger container where the evaporated fuel can condense and run back into the tank, or else into a charcoal canister that is plumbed to the engine intake, so that the evaporated fuel is eventually burned by the engine. This had NOTHING to do with preventing vapor lock, and was not primarily intended to allow the complete filling of the tank. It was a response to a Federal mandate.
My 1972 Nova had the charcoal canister. My 1971 D100 had a simple vent line going to a larger segment of tube, which I think had an overflow that went through the floor.
Starting whenever the Federal mandate went into effect, gas caps were NO LONGER VENTED.
There is nothing about the evaporative emissions control system that harms performance. (Well, maybe it adds a pound or two of extra weight.) Removing it only demonstrates one's ignorance.
R.
The 3 prong filter has an orifice so it does not drop fuel pressure too much. Its supposed to be around .050". Running the return back to the 1/4 nipple on the sender should be fine. In normal operation it will simply dump some fuel back in the tank and the circulation will keep things cooler to help prevent vapor lock. If the line gets hot and vapor does form, the separator will direct it back to the tank also. By the time it makes it back, it may cool and turn back to liquid but either way you are at least helping prevent vapor in the engine compartment.
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Re: Fuel Pressure Regulator w/ Return to Help Vapor Lock
[Re: ahy]
#1628246
06/04/14 10:16 PM
06/04/14 10:16 PM
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Joined: Jul 2007
Posts: 1,526
North Carolina
cjskotni
OP
pro stock
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OP
pro stock
Joined: Jul 2007
Posts: 1,526
North Carolina
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If I got something like this:  Does it have 3/8" nipples for the in/out so it will work well with my fuel line? Also, how does this thing bolt to the engine so it doesn't bounce around? Or do I need this style since my car is a 73? 
Last edited by cjskotni; 06/04/14 10:18 PM.
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Re: Fuel Pressure Regulator w/ Return to Help Vapor Lock
[Re: cjskotni]
#1628247
06/04/14 10:29 PM
06/04/14 10:29 PM
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Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
Challenger 1
Too Many Posts
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Too Many Posts
Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
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Quote:
If I got something like this:
Does it have 3/8" nipples for the in/out so it will work well with my fuel line? Also, how does this thing bolt to the engine so it doesn't bounce around?
That's the hot ticket, be sure there is a restriction for the return. No you can't use 3/8".
5/16" is the correct outlet size with a 3/8 inlet on the fuel pump. That how the fuel pump works best.
Everyone is hung up on 3/8, you don't need 3/8 from the pump to the carb. Even 3-2s or a hemi screaming at full song, as evidence of this filter/separator is only supplied by 5/16. It's a short run and 5/16" is more than enough.
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Re: Fuel Pressure Regulator w/ Return to Help Vapor Lock
[Re: cjskotni]
#1628248
06/05/14 06:50 AM
06/05/14 06:50 AM
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Joined: May 2008
Posts: 5,399
Aurora, Colorado
451Mopar
master
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master
Joined: May 2008
Posts: 5,399
Aurora, Colorado
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I used the Carter performance pump, and Hemi vapor separator, and did not have any fuel problems.
The reproduction vapor separator is expensive, I think $50, but it is setup for 3/8" lines. The fuel filters with vapor port I think are 5/16" fuel line, but only cost a few bucks. Really, you could just add a "T" to the fuel line before the carb, and install a restriction in the line that returns to the tank. You just want to maintain a minimum steady flow of fuel through the fuel pump and lines.
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Re: Fuel Pressure Regulator w/ Return to Help Vapor Lock
[Re: 451Mopar]
#1628249
06/05/14 08:32 AM
06/05/14 08:32 AM
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Joined: Jan 2003
Posts: 5,444
Indiana
YO7_A66
master
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master
Joined: Jan 2003
Posts: 5,444
Indiana
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"" Really, you could just add a "T" to the fuel line before the carb, and install a restriction in the line that returns to the tank. You just want to maintain a minimum steady flow of fuel through the fuel pump and lines""
The brass fitting that I shown in my previous reply is in this "T". 3/8" in and 3/8" out and I can adjust the flow back to the tank with a simple jet change. It is not stock but it flows well.
1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
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Re: Fuel Pressure Regulator w/ Return to Help Vapor Lock
[Re: YO7_A66]
#1628250
06/07/14 03:57 PM
06/07/14 03:57 PM
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Joined: Jul 2007
Posts: 1,526
North Carolina
cjskotni
OP
pro stock
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OP
pro stock
Joined: Jul 2007
Posts: 1,526
North Carolina
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Well I pulled the fuel pump and checked the push rod and compared it to the new rod I just got from Mancini. The rod is the exact same length as the new one with no wear I can discern. I am guessing a worn rod isn't my issue. :-( If this isn't vapor lock, I am open to suggestions on what else to check... As far as the hemi/440-6 setup, how did the factory hook all that up? Was there a hard line from the pump outlet to the vapor separator inlet? Did you just use a barb on the outlet and run rubber line to the separator? Where does that little tab on the vapor separator mount on the engine? Thanks! 
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Re: Fuel Pressure Regulator w/ Return to Help Vapor Lock
[Re: Challenger 1]
#1628252
06/07/14 08:44 PM
06/07/14 08:44 PM
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Joined: Jul 2007
Posts: 1,526
North Carolina
cjskotni
OP
pro stock
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OP
pro stock
Joined: Jul 2007
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North Carolina
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Thanks for the pictures! I ordered the return line, vapor separator, and a hemi fuel pump (3/8" inlet). I am going to ditch the Holley just in case that is the issue. Is this going to be a pretty sure way to fix this vapor lock issue? Is there anything else I need to do to help this or will the return line pretty much get rid of it? Thanks!
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Re: Fuel Pressure Regulator w/ Return to Help Vapor Lock
[Re: cjskotni]
#1628253
06/11/14 08:25 AM
06/11/14 08:25 AM
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Joined: Jul 2007
Posts: 1,526
North Carolina
cjskotni
OP
pro stock
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OP
pro stock
Joined: Jul 2007
Posts: 1,526
North Carolina
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I should have some of the parts creeping in here soon... Do I need/should I use any type of fuel filter between the separator and the carburetor? Will this separator be enough to strain the fuel and keep the carb from getting trash in it? I also thought of why the 73+ style VS has the funky bracket as those years originally had the passenger side exit on the WP housing. I am guessing this would interfere with the placement of the VS right on the pump there. Luckily I switched to the driver's side WP housing on mine years ago to make it easier to find an aluminum radiator that would work. If this doesn't fix this stalling issue, I think I am going to  this car and collect insurance money! 
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Re: Fuel Pressure Regulator w/ Return to Help Vapor Lock
[Re: cjskotni]
#1628255
06/11/14 03:02 PM
06/11/14 03:02 PM
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Joined: Feb 2003
Posts: 1,142
Tucson, AZ
cruzin
super stock
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super stock
Joined: Feb 2003
Posts: 1,142
Tucson, AZ
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I'm a little late to the party however, if your hood clearance permits, consider adding a carb spacer/insulator.
Another simple solution is "T" off of the rear, secondary carb feed line. This added outlet coming off the carb feed line can then either be ran back to the 1/4" port on the sending unit or use a fuel filter with an added port such as Fram filter G3499 and run the return to the filter. If you run it back to the tank, this provides a loop or circulating fuel system.
Last edited by cruzin; 06/11/14 03:03 PM.
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Re: Fuel Pressure Regulator w/ Return to Help Vapor Lock
[Re: cjskotni]
#1628258
06/11/14 10:06 PM
06/11/14 10:06 PM
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Joined: Aug 2003
Posts: 12,291
Kent, Wa
340SHORTY
Truck Nut
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Truck Nut
Joined: Aug 2003
Posts: 12,291
Kent, Wa
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having a dual inlet carb makes it easy to fab an inexpensive return line. dont try to reinvent the wheel.
I am truckless..
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Re: Fuel Pressure Regulator w/ Return to Help Vapor Lock
[Re: cjskotni]
#1628259
06/12/14 12:01 AM
06/12/14 12:01 AM
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Joined: Dec 2007
Posts: 18,157
Mass
DAYCLONA
I Live Here
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I Live Here
Joined: Dec 2007
Posts: 18,157
Mass
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Quote:
Quote:
Did you ever check to see if fuel is drippling in the secondary venturis while the car is ideling after a few minutes?
I have not as I pulled the pump to check the push rod and the car is laid up now until I get this fuel system put back together. Why am I checking for this?
Your chasing a lot of "ghosts" looking for the one that's causing your fuel woes, I'm trying to steer you towards the basics, so that you can eliminate them from your list....based on the descriptions of your fuel woes, a leaking rear (secondary) float/needle assy can cause a car to run ragged at low speed cruise conditions, or stall at idle/low speed conditions, and result in troublesome restarts after stalling due to the excess fuel conditions, it can be perceived as a no fuel situation, when in actuality the engine is flooded, simple test, with the engine idling, give it a few revs, then let it idle, check the rear/secondary venturis with your finger if they are wet with gas, or you can see visible signs of gas dripping from them, or the air bleeds, you may have a "sunk" float, or bad /dirty needle assy
Mike
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