Vicfreg 771 Report post Posted January 6, 2018 Larry, great question on the vapor state. Vapor pockets that are in the form of gas entrapped in liquid are compressible, so until the pressure on the FCC side gets high enough to collapse the vapor pocket, or the pressure of the vapor pocket gets above 0.32 psi, the loop seal won't clear. Based on your descriptions, I think the simple answer is that, in your case, you have some vapor build up in the FCC vent line. This is why you see that "spitting" into your filler neck. (Kinda like when you first hook up a garden hose, it spits air and water until all the air is pushed out). My guess as to why this is happening after you shut the car off is that as the fuel in the FCC vent line cools down, the vapor pockets collapse, and you get this "chugging" or "spitting" effect until the loop seal is clear. At any rate, I am glad it works! There is lot of literature on the boiling point of gasoline. It varies with the chemical composition, temperature and pressure. At atmospheric pressure, I have seen evidence/videos of gas boiling around 160 degrees F. (If you are into Chemical Engineering, you can google what is called the "True Boiling Point" for Petrol and read for the next year about distillation curves.... good luck....) Thanks for the info. I will be installing my system over the next few month, and will post details on my 1970 Convertible Thread, and some higher level details on this thread. . Quote Share this post Link to post Share on other sites
Topless69GT 28 Report post Posted January 13, 2018 I was involved with this post when it started. When I installed my FiTech EFI I was not going to run a return line. I ended up running the return line to the filler neck after reading posts, most notably the one from Larryc94.Just wanted to update what I ended up doing. Quote Share this post Link to post Share on other sites
larryc94 38 Report post Posted January 13, 2018 I'm glad I had a little influence on you and maybe saved a vintage Mustang becoming a fireball. You'll sleep better Quote Share this post Link to post Share on other sites
Shep69 149 Report post Posted January 13, 2018 On 1/6/2018 at 6:23 AM, larryc94 said: Those are some calculations, I know it just works. BTW what happens when the gas is in a vapor state! I know the fuel in the CC has had to been boiling at some point. It get hot under hood, no a/c and can feel the heat inside cabin but has never affected anything The command centre is a good idea in theory but it has issues. Most people who are using them end up doing this mod to help with the boiling issue. I went on my first real run today and covered 100 Km. It was pretty hot , around 37c . I had the A/C on the whole time and the FiTech performed flawlessly . Love It. Quote Share this post Link to post Share on other sites
Shep69 149 Report post Posted January 13, 2018 To the guys who have put the return line back to the filler neck , how did you connect the fuel line to the neck. Any pics . Quote Share this post Link to post Share on other sites
larryc94 38 Report post Posted January 13, 2018 Drilled and tapped neck 1/8 npt x 1/4 barbed fitting Quote Share this post Link to post Share on other sites
Shep69 149 Report post Posted January 13, 2018 5 hours ago, larryc94 said: Drilled and tapped neck 1/8 npt x 1/4 barbed fitting The filler neck is pretty thin Larryc94 . Did you have to put a nut on the inside ? Also did you use any sealer. Thanks Mark. Quote Share this post Link to post Share on other sites
larryc94 38 Report post Posted January 13, 2018 It's thicker than you think, used some teflon tape and taper of npt seals fine. Never seen any stains or leaks in 2 years. The problem is you can't have anything protrude it won't fit the opening. You could build a bead of weld to drill and tap. You mite have file the rear panel opening 1 Shep69 reacted to this Quote Share this post Link to post Share on other sites
Vicfreg 771 Report post Posted January 13, 2018 Shep thanks for the pic. I am headed toward the drill and tap project. I have a couple filler necks, worst case I will drill and have a bung welded on it. Quote Share this post Link to post Share on other sites
Vicfreg 771 Report post Posted January 13, 2018 Interesting video as well. Not planning on doing that until I give it a try in stock configuration. Quote Share this post Link to post Share on other sites
larryc94 38 Report post Posted January 13, 2018 My CC has been trouble free that I started to worry I might problems. So this summer I took it apart to check for problems others have reported. Looked for excessive assembly grease, debris, sock folded or too close to the bottom and loose fuel hose clamps on the pump. I found nothing wrong. put it back together and made sure I had towing coverage on my ins. Still running stock configuration, but I do have the revised vent with no check ball just the bronze screen Quote Share this post Link to post Share on other sites
RPM 1,190 Report post Posted January 13, 2018 3 hours ago, larryc94 said: My CC has been trouble free that I started to worry I might problems. So this summer I took it apart to check for problems others have reported. Wow. Your unit is trouble free and you take it apart to see if it has issues others are having? You are much more energetic than me young man. 1 Shep69 reacted to this Quote Share this post Link to post Share on other sites
Shep69 149 Report post Posted January 14, 2018 4 hours ago, Vicfreg said: Shep thanks for the pic. I am headed toward the drill and tap project. I have a couple filler necks, worst case I will drill and have a bung welded on it. Like Larry said ,once you weld anything to the filler good luck getting it through the hole In the tail panel . Quote Share this post Link to post Share on other sites
larryc94 38 Report post Posted January 14, 2018 21 minutes ago, RPM said: Wow. Your unit is trouble free and you take it apart to see if it has issues others are having? You are much more energetic than me young man. Have been down the road of "leave well enough alone" and question myself why I didn't 1 RPM reacted to this Quote Share this post Link to post Share on other sites
Shep69 149 Report post Posted January 14, 2018 Another thing I did the other day was to put a relay on fuel pump circuit. FiTech says you don’t need one but I had a hidden switch in line for security and the switch was getting pretty warm. The pump only draws about 7 amps so I thought it would be ok but just to be on the safe side I installed the relay. For those using the CC you need a special solid state relay so you can adjust the pump speed. Quote Share this post Link to post Share on other sites
ray1970 88 Report post Posted January 14, 2018 I also installed a relay to the CC unit but it was to stop the melting of wires at the throttle body main connecter and the burning out of the main board. Done both in the past..... Currently waiting for its return from the forth vacation to the great state of California. 4 week turn around at the least....... Quote Share this post Link to post Share on other sites
larryc94 38 Report post Posted January 14, 2018 7 minutes ago, ray1970 said: I also installed a relay to the CC unit but it was to stop the melting of wires at the throttle body main connecter and the burning out of the main board. Done both in the past..... Currently waiting for its return from the forth vacation to the great state of California. 4 week turn around at the least....... I keep checking for the melted connector and can't find any signs at all. My terminal's are fine and it is 2 yrs so past warranty Quote Share this post Link to post Share on other sites
Vicfreg 771 Report post Posted January 15, 2018 Larry, is the revised vent something you did, or did FiTech change their design? Ray, which connector is melting, the one with the orange and red wire? Quote Share this post Link to post Share on other sites
larryc94 38 Report post Posted January 15, 2018 Fitech revised the design, they were using a check ball and it was getting jammed and not venting. I think it was a poor design by only letting gas or vapor out. But creating vacuum if it needed to draw air in the CC If you look down the vent and see a bronze filter it's the update On the redesigned harness and connector your right about the red and orange wires were larger terminals in a separate plug with larger gauge wire Quote Share this post Link to post Share on other sites
Vicfreg 771 Report post Posted January 16, 2018 Hi Larry. Thanks for the info. My FCC has the vacuum line port on the top, so it is the latest version, I believe. I do have the 2 plug power harness and a separate 4 wire harness with the signal wires. My power harness has at least 14awg wires. Quote Share this post Link to post Share on other sites
larryc94 38 Report post Posted January 16, 2018 27 minutes ago, Vicfreg said: Hi Larry. Thanks for the info. My FCC has the vacuum line port on the top, so it is the latest version, I believe. I do have the 2 plug power harness and a separate 4 wire harness with the signal wires. My power harness has at least 14awg wires. They all have a vacuum port on the regulator, it's only maybe in the past year there know saying to hook it up to a vacuum source Quote Share this post Link to post Share on other sites
Vicfreg 771 Report post Posted January 16, 2018 Wow, interesting... Sounds like we all are the R&D platform for this product. But, I am going to give it a try. Quote Share this post Link to post Share on other sites
larryc94 38 Report post Posted January 17, 2018 26 minutes ago, Vicfreg said: Wow, interesting... Sounds like we all are the R&D platform for this product. But, I am going to give it a try. Most of stuff we are. A great company like MDL has figured out in there 69-70 hydraulic kit they changed the bore size of the master because reports of not enough throw. I have the early kit (about 3yrs old) and it's struggle to get enough throw, I have enough but had to maximize every adjustment Quote Share this post Link to post Share on other sites
Vicfreg 771 Report post Posted January 17, 2018 Oh, I have not picked my master cylinder yet, so I am very interested in some details. Quote Share this post Link to post Share on other sites
larryc94 38 Report post Posted January 17, 2018 5 minutes ago, Vicfreg said: Oh, I have not picked my master cylinder yet, so I am very interested in some details. I don't have the details of the sizes and I don't think they list them in the description on there site (this is for the clutch) Quote Share this post Link to post Share on other sites
