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Fuel Pressure Regulator w/ Return to Help Vapor Lock
#1628220
06/03/14 08:01 PM
06/03/14 08:01 PM
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Joined: Jul 2007
Posts: 1,526
North Carolina
cjskotni
OP
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North Carolina
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Guys, I have a rather lengthy thread going where I am possibly combating a vapor lock situation. I have a 3/8" SS fuel line from the tank to the pump (mechanical). I have already put a thermo-tec sleeve on the line where it runs past the headers which helped but apparently still not enough. I am guessing my next step will be to put in a return line to help keep the fuel cool. My sender has a 1/4" port for a return line which I don't have yet but can plumb in. The only place I can think of to add a return line would be with a fuel pressure regulator. Has anybody done this and can point me in the right direction to which unit will work? Also will this have a good chance of curing this before I dump the money and time into this? I need a fuel pressure regulator that will: - work with a 1/4" return line - work with a mechanical pump that puts out 7-9 psi at idle - be small and unobtrusive as I don't want to have to make my engine bay look like a race car Any pointers or tips or experiences doing this? Thanks!! 
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Re: Fuel Pressure Regulator w/ Return to Help Vapor Lock
[Re: cjskotni]
#1628221
06/03/14 09:06 PM
06/03/14 09:06 PM
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Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
Challenger 1
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Cincinnati, Ohio
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I have loosely followed your other thread. I know you mentioned a coupled different hoses between the tank and the hard line going up to the mechanical pump? I would be very susbitious of a leak there or blockage. It don't take much on the suction side of a pump, it may not leak fluid but it can suck air. Then maybe try a reg airtex pump? I run them and have had good luck with them. Here's a option for a return line. I use a hemi vapor separator bolted to the fuel pump with a #57 orifice in the return line. Been this way since about 2003 and have driven the car hard at hi altitudes and very hi temperatures at hi altitudes and it has never let me down. Non of my stock fuel line was insulated. I drove it wide open for like 5 or more miles at a time out in Bonneville on the salt on a 95 degree days, 3 different years and it never ran out of fuel. Do you know how hard it is to drive 120 MPH for like 5 miles at a time? Anyway here's pictures of my junk. I included a picture of my gas tank connections, simple and sweet, not much chance of sucking air here. If your car model ever came with a hemi, then you can order a pre bent 1/4" return line. Even if your car didn't come with a hemi I would call fine lines and ask them to bend up one for you in 1/4" just like your suction line and it will fit fine I'm betting.   Couple water pump bolts came loose and caused the rust stains. I haven't taken the time yet to pressure wash it off in this photo. Quality Tawan dipstick, no china crap on this motor. lol  I took it to Vegas last July, it was 110° pretty much 24/7. I idled it around for over a hour at time 3 times until I got smart and did my cruising at 6am so at least I could motor around with less traffic. One of many examples of extreme service is all I'm saying. Stock ain't always bad. Good thing my black car has AC otherwise it would be unbearable. 6AM the Vegas "strip" It was all mine, kinda. 
Last edited by Challenger 1; 06/04/14 07:42 PM.
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Re: Fuel Pressure Regulator w/ Return to Help Vapor Lock
[Re: Challenger 1]
#1628222
06/03/14 09:46 PM
06/03/14 09:46 PM
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Joined: Jul 2007
Posts: 1,526
North Carolina
cjskotni
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I am pretty sure I have no leaks between the pump and sender. I replaced the 3/8" line to -6AN braided line with a rubber hose and fuel barb for the pump. I can get the pre-bent 1/4" return line for my car so not an issue there. What I need to know is how/where to plumb that return line into the fuel system near the motor. Does your fuel pump have a return line port on it?? Where did you tap in for your return line? The only way I can see doing this is to add the pressure regulator with the return bypass but I am not sure if those are really designed for what I am trying to do here as they have HUGE ports on them it seems. I can't be the only person here who wants to cure this vapor lock issue without going to an electric pump or something. 
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Re: Fuel Pressure Regulator w/ Return to Help Vapor Lock
[Re: cjskotni]
#1628223
06/03/14 10:05 PM
06/03/14 10:05 PM
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Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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T at the carb inlet & run it to the reg to one of the "in" ports & cap one of the (2) "out" ports with a NPT plug and run the other "out" port back to the 1/4" nipple on the sending unit. Use a "red" holley low psi reg. If running a holley dual inlet chrome line T at the upstream hose barb end that's where to T and where to add a port to check fuel psi
live every 24 hour block of time like it's your last day on earth
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Re: Fuel Pressure Regulator w/ Return to Help Vapor Lock
[Re: cjskotni]
#1628224
06/03/14 10:18 PM
06/03/14 10:18 PM
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Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
Challenger 1
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Cincinnati, Ohio
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Quote:
I am pretty sure I have no leaks between the pump and sender. I replaced the 3/8" line to -6AN braided line with a rubber hose and fuel barb for the pump.
I can get the pre-bent 1/4" return line for my car so not an issue there. What I need to know is how/where to plumb that return line into the fuel system near the motor. Does your fuel pump have a return line port on it?? Where did you tap in for your return line?
The only way I can see doing this is to add the pressure regulator with the return bypass but I am not sure if those are really designed for what I am trying to do here as they have HUGE ports on them it seems.
I can't be the only person here who wants to cure this vapor lock issue without going to an electric pump or something.
The stock factory hemi vapor separator act's as a filter and a vapor separator and has return nipple on it, on the bottom that goes directly to the return line that is right next to your suction line on the inside frame rail. All factory stock and works well for me with a #40-60 restriction in the return nipple. I run no other filter, just the VS at the fuel pump.
But I really don't think this will solve your problem, it's something else IMO.
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Re: Fuel Pressure Regulator w/ Return to Help Vapor Lock
[Re: Challenger 1]
#1628225
06/03/14 10:25 PM
06/03/14 10:25 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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what carb are you running ??
I am truckless..
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Re: Fuel Pressure Regulator w/ Return to Help Vapor Lock
[Re: 340SHORTY]
#1628226
06/03/14 10:38 PM
06/03/14 10:38 PM
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Joined: Jul 2007
Posts: 1,526
North Carolina
cjskotni
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Quote:
what carb are you running ??
Holley 4150 vacuum secondaries
Quote:
But I really don't think this will solve your problem, it's something else IMO.
What do you think it is? The only other thing I can really imagine would be the pushrod. Are you thinking a worn rod could really cause these exact symptoms?
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Re: Fuel Pressure Regulator w/ Return to Help Vapor Lock
[Re: 340SHORTY]
#1628227
06/03/14 10:43 PM
06/03/14 10:43 PM
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Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
Challenger 1
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Quote:
what carb are you running ??
Me?
If so a 600cfm 1405 eddie on a victorjr340 manifold with a air gap and eddie heads with no heat risers. It's perfect for the desert as it turns out. 
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Re: Fuel Pressure Regulator w/ Return to Help Vapor Lock
[Re: cjskotni]
#1628228
06/03/14 10:47 PM
06/03/14 10:47 PM
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Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
Challenger 1
Too Many Posts
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Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
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Quote:
Quote:
what carb are you running ??
Holley 4150 vacuum secondaries
Quote:
But I really don't think this will solve your problem, it's something else IMO.
What do you think it is? The only other thing I can really imagine would be the pushrod. Are you thinking a worn rod could really cause these exact symptoms?
YES!
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Re: Fuel Pressure Regulator w/ Return to Help Vapor Lock
[Re: 340SHORTY]
#1628230
06/04/14 12:38 AM
06/04/14 12:38 AM
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Joined: Jul 2007
Posts: 1,526
North Carolina
cjskotni
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OP
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North Carolina
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Quote:
No
I havnt seen your other post . Why do you think you are getting vapor lock ?
Can it be heat soak instead?
Already I see 1 problem. You are running a fuel pump that puts out to much pressure for a carbed fuel system. 5PSI is the max for a Holley and E Brokes about 4 PSI is max.
Here is the post for some good, long bedtime reading: https://board.moparts.org/ubbthreads/show...e=0#Post8075157
I always heard Holleys like 7psi but I do agree my pressure is borderline high.
When you say 'heat soak' that is a form of vapor lock, right? As in residual heat boils the fuel in the lines/bowls causing it to flood the motor and/or lose pressure? I can see this being part of the problem but this car will cut off/sputter during cruising which would not be heat soak.
I'd just like to see somebody chime in with a similar problem and what they did to diagnose and fix it....
BTW, I ordered a new pushrod from Mancini. I will pull my rod this weekend if I have the time and measure it to see if it has any wear.
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Re: Fuel Pressure Regulator w/ Return to Help Vapor Lock
[Re: Cab_Burge]
#1628234
06/04/14 05:36 PM
06/04/14 05:36 PM
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Joined: Jul 2007
Posts: 1,526
North Carolina
cjskotni
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Quote:
Quote:
Challenger1 is right on the money. The vapor separator is designed to provide a return to the tank. MY 70 Cuda 318 came a return connected to the separator.
Mopar started addressing the vapor lock problems back in the mid 1960s on the street hemi cars and other Hi Po models with the fuel filter vapor return lines. My wifes 1986 Ram 250 van has a 318 in it with this fuel filter  You can buy them at almost any parts house, buy one and try it mounted between the fuel pump and the carb. 
Does anybody have a part number or application I can use to find this particular filter?
I am also confused as to the difference between a 'vapor line' and a 'return line'. They are not the same thing, right?
I have a vapor seperator directly in front and above my fuel tank but that connected to the VAPOR LINE which would go the charcoal canister. Wasn't this used to contain fuel vapor from the tank and allow the motor to suck these in an burn them instead fo just venting to the air? You wouldn't want liquid fuel returning on this line as the tank could then not vent?? My car had a vapor line/canister which is long gone now.
My car did not have a FUEL RETURN LINE as far as I know. My sender only had a single 5/16" nipple for the fuel line. Therefore nowhere to connect a return as far as I know. That being said the sender I have in there now does have a 1/4" nipple for a return line so I should be good. I just want to clarify that when you reference a 'vapor seperator/flilter', you mean that black box and NOT the seperator back by the tank for venting...
The only issue I can see with this filter you are suggesting is that I run a 3/8" fuel line and my fuel hose is now going to be a size too large. Do they make these filters with 3/8" nipples for the in/out and 1/4" for the return?
Thanks!
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Re: Fuel Pressure Regulator w/ Return to Help Vapor Lock
[Re: cjskotni]
#1628235
06/04/14 05:50 PM
06/04/14 05:50 PM
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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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I made my own return fitting by using some brass fittings and a carb jet. I was told to locate the return fitting as high up on the fuel line as possible, then route back to the tank. I had these pieces laying around so once I was done, I started out testing with a couple of jet sizes and I ended up with a .052 jet as the oriface size for the return.
I took the brass barb fitting and tapped the inside for a 1/8npt thread. Then I took a 1/8npt plug and drilled/tapped it for a Holley style fuel jet. I started with a #60 and the idle psi was around 6.5psi. Then I swapped in a #52 jet and the idle psi went up to about 6-3/4psi or so. My electric fuel pump is rated at 7psi and I do not have a return regulator. (If I remmber correctly, the QF carbs are rated at 7-7.5psi at idle).
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]
#1628236
06/04/14 06:03 PM
06/04/14 06:03 PM
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Joined: Jul 2007
Posts: 1,526
North Carolina
cjskotni
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Quote:
I made my own return fitting by using some brass fittings and a carb jet. I was told to locate the return fitting as high up on the fuel line as possible, then route back to the tank. I had these pieces laying around so once I was done, I started out testing with a couple of jet sizes and I ended up with a .052 jet as the oriface size for the return.
I took the brass barb fitting and tapped the inside for a 1/8npt thread. Then I took a 1/8npt plug and drilled/tapped it for a Holley style fuel jet. I started with a #60 and the idle psi was around 6.5psi. Then I swapped in a #52 jet and the idle psi went up to about 6-3/4psi or so. My electric fuel pump is rated at 7psi and I do not have a return regulator. (If I remmber correctly, the QF carbs are rated at 7-7.5psi at idle).
Where did you put this fitting? Also, that brings up another question is that if I do add this filter/seperator, it is just acting like a tee in the fuel line. Won't this 1/4" return line cause a signicant drop in fuel pressure to the carb unless you do restrict it (like with the jets)??
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Re: Fuel Pressure Regulator w/ Return to Help Vapor Lock
[Re: Steve Bryant]
#1628238
06/04/14 06:12 PM
06/04/14 06:12 PM
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Joined: Jul 2007
Posts: 1,526
North Carolina
cjskotni
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Quote:
On my Barracuda, the fuel pickup only had one line as your does that ran to the front of the car into the fuel pump. The fuel pump connected to the vapor separator which had one 5/16 line that ran up to the carb and one 1/4 line that ran to the back of the car and to the canister up in the trunk recess. In my setup, my gas tank has four lines that ran into a canister filter in the rear and one line ran up front to the vapor canister. I ripped all that and removed the vapor canister up front, removed the 1/4 return line and put a check valve on the open line that ran into the trunk recess. When I go to connect mine back up, I will buy a new vapor filter up front and I will run a new 1/4 line back to the trunk recess into that hose where I added a check valve.
I do not have part numbers but YearOne has replacements for all the parts I have mentioned and that is where I will get mine when I decide to run a new return.
If you run the fuel return line to the vapor seperator by the tank, how will your tank vent? Wouldn't you start getting a vaccum lock situation as your tank will not be able to pull in air to displace the gas your pump removes from it???
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Re: Fuel Pressure Regulator w/ Return to Help Vapor Lock
[Re: Steve Bryant]
#1628239
06/04/14 06:30 PM
06/04/14 06:30 PM
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Joined: Feb 2005
Posts: 28,312
Cincinnati, Ohio
Challenger 1
Too Many Posts
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Cincinnati, Ohio
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Quote:
On my Barracuda, the fuel pickup only had one line as your does that ran to the front of the car into the fuel pump. The fuel pump connected to the vapor separator which had one 5/16 line that ran up to the carb and one 1/4 line that ran to the back of the car and to the canister up in the trunk recess. In my setup, my gas tank has four lines that ran into a canister filter in the rear and one line ran up front to the vapor canister. I ripped all that and removed the vapor canister up front, removed the 1/4 return line and put a check valve on the open line that ran into the trunk recess. When I go to connect mine back up, I will buy a new vapor filter up front and I will run a new 1/4 line back to the trunk recess into that hose where I added a check valve.
I do not have part numbers but YearOne has replacements for all the parts I have mentioned and that is where I will get mine when I decide to run a new return.
Like Cab said above, only the hemi and 440/6paks got the vapor separator up front on the fuel pump and the return line to the sending unit. Now all aftermarket sending units have the return nipple. The return line was not very common on mopars. But it can be used and is the best way to run a return line on any motor and on most cars.
The vent separator in back(which has a different purpose than the one in front)was setup to join four vent hoses into one container where the fumes/liquid could separate/drain back into the tank. The four vent lines insures that the tank is vented even when it is full and the car is not parked level. The rear separator also insures that gas won't run out of your tank on the ground if it's parked full out of level.
The vent separator in the rear has a line that runs up front to the engine compartment up on top of the motor.(It's important to end on top of the motor because it's higher than the tank) Then gas and fumes will never spill out or be smelled in a closed garage.
There's nothing wrong or anything that can be improved from the factory venting. So I highly recommend to run the entire factory vent setup for your car model. This venting that I'm talking about has nothing to do with the fuel pump or the front mounted vapor separator.
The only thing I could see doing away with is the charcoal canister up front. So instead of terminating the vent line to it, you connect it to the breather on the valve cover just like they did it in 1971. My 71 is setup like that and it's always inside and I never smell gas.
I've replaced entire fuel systems here lately on 2 cars.
Last edited by Challenger 1; 06/04/14 07:05 PM.
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