Chevelles.com banner

21 - 34 of 34 Posts

·
Registered
Joined
·
499 Posts
I did read that thread just don't remember if anyone figured out what the check ball was supposed to do.

I don't know for sure where I am going with this but thinking out loud.....

With Mike's plan there will be 2 regulators in the system. The internal FCC one is 58 and the TB one is also nominal 58 but if the vacuum is hooked up presumably will vary a bit. Presumably with no vacuum signal the TB reg will be running at 58 so that would be either not hooked up or WOT? With a vacuum signal at say idle it will be lower? Seems like someone here said that FiTech told them they started hooking up the vacuum lines on all of them to improve idle quality so that is why I am thinking vacuum would lower the pressure.

So in theory fuel pressure leaving the FCC will be a steady 58. Any pressure over 58 that is generated by the FCC pump will be dumped back into the FCC before it leaves. If the vacuum is hooked up and it works the way I assume it works lets say at idle it drops the pressure to 45 there should then be some fuel leaving the TB and headed back to the tank. So as long as the TB regulator isn't at max/58 there should be some fuel returning. Most of the time I would guess this would be the case so it should do what we are expecting it to do. You won't spend much time at full throttle, if you did it would be back to factory design which was supposed to work in the first place so it should work for brief periods.
 

·
Registered
Joined
·
325 Posts
I'm not sure that hooking up a return line will work.
The Fi Tech system has three fuel inlet connections at the throttle body, you can use any one of them.
If you remove the plug from one of the inlets and connect the return line to that location. I'm wondering if that would just bleed off the fuel pressure that is generated between the FCC and the throttle body.
 

·
Registered
Joined
·
491 Posts
The Fitech has three inlets and one dedicated return port (which is behind the pressure regulator). The regulator maintains the proper pressure in the TBA.......so no problems using a return.
 

·
Registered
Joined
·
499 Posts
Hooking a return to one of the inlet ports would bleed off most of the fuel pressure. What is being talked about here is hooking up to the return port which is after the built in regulator. I was questioning how much fuel you would get that way and would 2 regulators set pretty close to the same pressure do anything odd? Would they fight each other and cause osculations?
 

·
Registered
Joined
·
43 Posts
I was having FCC venting issues and thought about running a return to the tank from the throttle body. The problem I thought might happen was that the fuel in the command center would be drained faster than the mechanical fuel pump could replenish it ??
Anyway, I disconnected the FCC from the OEM vent system and instead vented it into a return line at the top of the tank...problem solved.
The FCC vent should be labeled a return as a lot of liquid and vapour fuel travels through it when cold or much more so when hot.
 

·
Registered
Joined
·
499 Posts
Interesting theory about not having enough volume from the mechanical/low pressure pump. I had not thought about that. With the specific system in question I don't think there will be that much fuel from the return since there is still the regulator in the FCC but for sure you will be loosing some that way. How much and will it be a problem are good questions. If you didn't have the regulator inside the FCC I could see it being a problem but since it will be dealing with most of the excess fuel I suspect it will be ok. If it wasn't Ok would you upgrade to a higher volume pump? Would that then bring you back to the original problem?
 

·
Registered
Joined
·
798 Posts
I installed a Holley regulator on the fuel inlet line to the FCC before doing this the inlet pressure was 8 to 9 psi and fuel was blowing out the vent.

Turned the pressure down to 3 psi no more issues with venting ran the vent line back to the tank T into the filler line anyway have pulled this line off and left it hanging down while driving and stopped and checked it no fuel venting

FCC runs cooler as well........higher pressure increases heat.....4000 miles on this setup works great.


Works for me anyway



 

·
Registered
Joined
·
68 Posts
Discussion Starter #29
I installed a Holley regulator on the fuel inlet line to the FCC before doing this the inlet pressure was 8 to 9 psi and fuel was blowing out the vent.

Turned the pressure down to 3 psi no more issues with venting ran the vent line back to the tank T into the filler line anyway have pulled this line off and left it hanging down while driving and stopped and checked it no fuel venting

FCC runs cooler as well........higher pressure increases heat.....4000 miles on this setup works great.


Works for me anyway



Cool deal. I think I am going to try this method first and see what happens. Just ordered a regulator. Thanks for the info.
 
  • Like
Reactions: rel3rd

·
Registered
Joined
·
27 Posts
I've had no dramas with my FCC yet, including when driving on 40C (105F) days. I did have two return lines to the tank available to me (original pump return and charcoal canister), so I used both, with a vertical run on one of them where it teed off to hopefully avoid any liquid fuel entering it. No dramas now with about 650 miles on it, however my intention if I do have a problem is just to remove the float arrangement completely, converting the vent line into a return, allowing excess fuel from the mechanical pump to just be pumped back to the tank. I believe this would solve all the heat/boiling fuel/air lock/fuel trapped in the vent line issues.
 

·
Registered
Joined
·
1 Posts
Curious. Read through this entire thread with vested interest. No conclusions.
Did anyone ACTUALLY run the FCC with a return line from the TB?
Can a mechanical pump keep up with a free flowing TB return setup?
Definitely some great ideas here!
 

·
Registered
Joined
·
277 Posts
Curious. Read through this entire thread with vested interest. No conclusions.
Did anyone ACTUALLY run the FCC with a return line from the TB?
Can a mechanical pump keep up with a free flowing TB return setup?
Definitely some great ideas here!
I have seen some users removing the float from the FCC so it never stops flowing and will use the "vent" line as a return. Still deadheading to TB though.

If you want to make it a true sump, then using the return on the TB, and returning to the FCC, not the tank, would be the best option. Similar to how the PowerSurge tank works. I have never had an issue with my PowerSurge, and I run it at PWM of 100. (Walbro 255 pumps don't like PWM)
 

·
Registered
Joined
·
46 Posts
I installed a Holley regulator on the fuel inlet line to the FCC before doing this the inlet pressure was 8 to 9 psi and fuel was blowing out the vent.
I guess I got lucky. I replaced my holley blue pump with the Mr Gasket 12S inline pump. No regulators. I'm seeing 3 to 4 psi at the FCC. The Mr Gasket pump is not quiet, but when compared to the blue pump, the Mr Gasket pump way less noisy.

I purchased my FCC from Jegs, hoping it is of recent manufacture date. For sure I'll take the advice in this thread and figure out a way to get some fresh air onto the FCC or at minimum a heat shield between my radiator and the FCC.
 

·
Registered
Joined
·
277 Posts
Hi all,

So I have a FiTech GoStreet and FCC that I ordered from FiTech long before all the issues came up with the FCC. From how I have read things, it seems the biggest issue is the pump is deadheaded (returnless) and heats up the fuel in the can, causing it to vent fluid and causing all sorts of issues.

I was just thinking, if I ran the high pressure line from the FCC to the TB and then a return line back to the tank (like an external pump setup), in theory this does not deadhead the pump and should keep it cooler, possibly solving the main issue the FCC seems to be having.

Anyone think this would work?
It would work, and you don't need the return pump. It would feed excess on it's own. Also will need to remove the float, and the vent check ball if it's there.

One of our members also just removed the float and checkball, with out doing the throttle body return, so instead of the float closing and stopping fuel from the low pressure side when full, it would just push excess fuel to the tank. So far it's worked.

But I personally would do the throttle body return, but that's also why I went with a RobbMC PowerSurge instead of the FCC. And never have issues like the FCC people do.
 
21 - 34 of 34 Posts
Top