Did a search and didn't find what I was looking for -

I have purchased the Holley Terminator EFI system and a new holley fuel tank with the in tank pump

Question #1 - old fuel tank has the fuel supply, and vapor return line fittings for the 2 steel lines that run down passenger side. also has 2 ports that tee into each other and go to the vapor canister. New fuel tank only has the 1 fuel supply line and the 2 ports that tee to the vapor canister - EFI requires a return line so I will need to use one of the vapor lines - does it matter which one? one port is in thank, the other is in the removable plate?

Question #2 - the EFI unit does not have the port/line that comes from the PCV valve and the fuel vapor canister - so do I just eliminate it?

thanks in advance

MD

 

Doesn't the Holley intank pump have a internal regulator? I thought all Holley intank setups did. If so that's why there is no return fitting. You don't need one. Throttle body does not need a return if the fuel pressure is regulated before the fuel gets to it.

 

I'm confused. If you bought the Holley in-tank fuel pump system, you don't need a return line. You probably want to upgrade your fuel line, though, as the original rubber is not rated to hold pressure.

Just to clarify, what Holley system or systems did you buy?

 

It sounds like the OP is attempting to install a aftermarket throttle body EFI system.
And hasn't even the slightest clue how things work, or even what he purchased.
I know that sounds horrible, but it's not all that bad.
there are a few of us on here that have a great deal of experience.
We will help.
First off. There is no such thing as a throttle body that must have a return. The injectors don't care where the pressure is regulated. As long as your running 58-60 PSI they will be happy.
second. How are you running your high pressure line from tank to throttle body?
third. Put up pic's of your setup. You do not want to undo the PCV. The charcoal canister is not necessarily but many live to argue with me.
And finally, if the OP here thinks he will hook up a couple wires, connect a fuel line and it'll purr like a kitten. He's in for a world of hurt.

 

True- they don't care- but-

A return system can react almost instantaneously to sudden fuel demands due to the fact the pumps are running 100% duty cycle with a mechanical pressure regulator down stream of the rails. A returnless system uses the pumps to regulate the pressure and have to "ramp-up" to meet a sudden fuel demand which will always lag behind a return system.
Also in a return system- the fuel is not deadheaded at th engine- which can result in issues white the superheated fuel- like when sitting in traffic.
The reason new cars are using the returnless system is for emissions- not that it's better....

 

Ack. I know you are trying to help but ack ok.

You seem to be mixing and matching fuel systems that have no place in this discussion!
First of all, A TRUE returnless system is a PWM control theory application with a dedicated fuel computer that monitoring fuel pressure and anticipating demand.
This type of control is generally reserved for OEM Direct Injection to my knowledge. Not applicable here.

What fuel systems DO belong in this discussion?
-Vapor regulation
-Port/Throttle body injection

The fuel pump in these type of fuel systems generally runs 100% PWM, e.g. Full voltage all the time "ON" Like any digital switch.
It IS possible to perform a PWM control over a general Carb/EFI application however this is beyond the scope of this discussion and unnecessary for majority of hobby installations.
What really happens is there MUST be a regulator and a return line. ALL Port/EFI engines up until direct have a return line, even those so labelled as "returnless". Yes returnless systems actually have a return line in around the fuel tank area, thus regulation happens near the fuel tank.
Whereever regulation occurs, that is the return line origin, for any non-direct injection + fuel computer applications including some carb. A carb can use a return line regulator or not, it has more options because of low pressure requirement.

For example on my engine I have a Regulator under the hood for V8 MPFI EFI. So I have a return line to the fuel tank. However, I also have a return less fuel rail. My rail is DEAD-HEAD and can vapor lock and all of that, hot fuel sitting in the rail all the time, even though I have a regulator and return line under the hood as well. The RAIL design determines if a return line from the rail is to be used or not. It can always be added to some rails but not all OEM rails can support a return line on the rail directly.

In this 'swap' conversion example there will be a return line somewhere and a regulation origin. I recommend regulator under the hood and a Vacuum Referenced regulator for ANY/ALL Performance applications without hesitation for 25 years. There are nuances for setting up successful fuel system. I Prefer a base fuel system pressure around 38psi. The lower the fuel pressure, the cooler the fuel will run, longer fuel pump lifespan, least wear and tear on fuel system components, and the most fuel the pump could possibly pump is at the lowest possible pressure, so it will not only give more pumping ability it will run cooler and last longer. Since the system needs to be tuned anyways there is no downside to starting off with a least pressure unless the injectors are too small in which case the injectors become the limiting factor with how reliable your fuel system COULD be. In other words jacking up fuel pressure to compensate for TOO SMALL of injectors is not a desirable, or reasonable 'fix' the correct fix is to run the necessary size injectors in the first place to get the fuel supply as reliable as possible. The Wide Open throttle setting for fuel injectors at max I recommend around 40% to 55% Duty cycle max to keep fuel injector drivers cool and allow for optimal injection phase window opportunity. Traditionally a duty cycle of around 80% is acceptable but those that know this offers poor window for WOT fueling onto closed intake valves understand the lost opportunity and fuel leaving the exhaust valve opening more frequently due to pre-overlap spray profiles in the injection phase table due to high duty cycle of an injector. This is a minor variable in the grand scheme but like I said there is nuance to setting up a fuel system for max reliability and engine performance and these are the highest level concepts to become aware of when extracting max efficiency/reliability from a setup you hope to daily driver (many thousands of hours of service not just racing and tearing down frequently).

Lets talk about pump feed and return requirements and ideas.
This sounds like a < 800rwhp installation so 5/16" or AN6 type of lines are good.
I recommend a HARD line for reliability. 5/16" Is fine I use it at 750bhp in daily drivers hard line hose clamped is TRACK LEGAL. For the short stretches between Hard-Line and fuel rail with Braided 6AN.
You can go to the auto store and get a large roll of 5/16" Hard line and a tube shaper/bender kit and make your own if needed. I used rivnuts for suspending it with OEM brackets I sourced from the junkyard.

You COULD use your existing lines if they are quality lines. Be aware of any rusting or bits of debris inside. Existing 5/16" Clean hard line is fine. 3/8" is obviously fine also it wont matter.
You will need 1 line pumping up to a regulation spot.
1 line for return.
And 1 line to the rail if its a dead-head style .
Some rails have a outlet which goes to the regulator, either way there is a regulator before or after the rail somewhere with a return line.

I'm thinking about this problem in terms of it being an antique/classic installation. What I like in those is using existing lines and factory components to support modern hardware. The use of original hardlines if they exist is ideal just be sure they are clean and properly supported away from hot exhaust fixtures and rotating objects etc... protected from the road debris and such.
You'll want to predict future line cutting/changing fittings, leave extra length in the hoses maybe a loop for when you need to cut them in the future.
Run a quality OEM style fuel filter if possible. I Like the one for Nissan 300ZX Twin Turbo 1992~ Its a giant filter supporting 800bhp+ from a 5/16" hose clamp style line. Good filtration I think around 2uM or something, I think its a paper style. You would also desire an easily accessible higher micron filter near the pump say 30uM which is hand-washable stainless or something. And then there is also the filter SOCK on the pump itself. 3 filters is ideal and an OEM style near the rail for the engine is perfect.

Classically the types of modern fuel pump offered for conversion EFI draw more amperage than people seem to expect. You will desire a high quality wiring to support the fuel pump and carefully monitor the voltage at first when everything is as hot as it can get. There is an interplay between the alternator, heating, wiring, amp draw, fuel system, which is difficult to describe briefly but I will try. As the voltage drops due to temperature (of fuel, car, wiring, engine, whatever) Injectors slow down and fuel pump voltage may begin to drop. The pump may further become warm contributing to this. If there is an excessive heating or voltage drop you must correct this before moving on. Do not ignore this potential issue because a large voltage drop can burn up the fuel pump or even start a fire depending on the fusing and wiring. Use a large wire that the pump manufacturer recommends and a proper fuse and dedicated source from the battery somehow, this just a common overlooked issue to mention how important it is.

Pressure test your fuel system when it is finished. There are two things to do in this way. First is place the car is a low flow environment (Like a garage) no wind and run the fuel system alone with the engine turned off. Just apply power to the fuel pump relay or use the EFI software to enable the pump so it just runs for a minute or two, them smell around all fuel fittings for leaking fuel.
You may also wish to watch the behavior of the fuel pressure but the regulators these days are all so wildly different sometimes they hold and sometimes they do not, and sometimes the pump checkvalve doesn't hold, it just depends. That is why I prefer the smell test for a fuel system leaking test.

_-- venting --- ___
The importance of venting properly and canister on the vehicle is to reduce the fuel smell of the vehicle, preventing gasoline vapors from being released around the car engine and fuel tank. It also assists with the filtering of incoming air to the fuel tank and checkvalving of pressure and vacuum of the fuel tank. The fuel tank pressure must not become much negative and it must not become too positive either. As air enters the fuel tank it will bring water so never leave high content alcohol fuel in the fuel tank for extended periods unless you fully sealed and check valved the fuel tank against atmospheric water intrusion. It isn't quite that simple but that is most of it.

Your EFI computer should have a needed output to control the EVAP solenoids necessary to drive the Vapor system like factory or nearly so.
You could examine the diagram and find places for improvements maybe using more modern solenoids or a modern canister from a newer vehicle.
You may wish to look into modern controllers for such a vapor control system.
Although it may be a pain the vapor control system is integral and dare I say essential for a complete fuel system installation

 

Bullshit. All the above.
seriously. The Holley system and the FiTech systems are modeled after GM Delphi systems. They are designed to run at 58 PSI. period.
The charcoal canister is all about fumes in your garage. 30 years without one. And no fumes!
Some things are correct above.
Yes there is a return. If it's in your tank like most Holley systems. Then it's in your tank. Just like a Harley Davidson motorcycle.
If it's just outside your tank, like a GM LS. Then there it is. But the point is you do NOT need a return from the throttle body unless you do not have a pressure regulator anywhere else.
Who does that?
These systems run the fuel pump at 100 percent, 100 percent of the time.
The Holley system and all its base maps are designed around 58 PSI fuel pressure.
Changing that thinking there will be a slight change in fuel temp would be far more effort than it's worth.
So,
To the above.
BULLSHIT

 

Oh, and the typical pump required for this system should pull about 9amps. Running. Full load. Yes, everyone should consider the extra electrical draw of EFI. but it's less than half that of electric cooling fans.

 

Funny the Admin of Holley EFI is in agreement with my method and setting up practices
https://forums.holley.com/forum/holl...418#post391418

You obviously do not have enough experience with EFI systems to be making those judgements. NO fresh installation with ANY base maps is going to run 100% perfectly they ALL need tuning. Therefore it is just as easy to start off with the correct fuel system pressure than to rely on 'popular belief' syndrome where you just blindly copy and tell everyone to do the same thing that everybody else is doing without thinking about WHY. WHY do you think they supply 60PSI for chevrolet cars without turbochargers but only 44PSI for Nissan skyline, Toyota Supra, etc... performance high output cars? WHY do you tune an engine and HOW do you tune an engine properly and what does it mean to tune an engine? It means the same thing as engineering anything else - you select for optimal ranges giving thought to SAFETY, RELIABILITY first if needed. I could go on but I have a feeling its deaf ears

 

Since the Holley Terminator term covers both TBI and control of LS-style fuel rail and direct injector systems, hopefully the OP gets back to us.

If you feel the need for a fuel pressure regulator mounted at the end of the fuel rail with a return, you can do that. This is how, say, the Buick 3800 engine handles the regulator. For example, this:

https://www.lsxconcepts.com/products...mbing-kit-copy

C5s have a fuel pressure regulator with a return that sits near the engine, but the engine still sees 58 psi. There are several EFI installs on this Forum that use that method. You get the same benefit of the return line that most stock C3 systems give you (can only get vapor lock in the last few feet).

The Holley system in-tank system spits out 58 PSI with no (external to the fuel tank) return. Like a 1-wire alternator, it is simple to implement, but not without drawbacks.

 

Just to be clear 60psi of fuel pressure is a travesty and should never happen to a performance vehicle anywhere in the world.

There is absolutely NO advantage for a performance vehicle to run that kind of pressure. ZERO advantages and MANY disadvantages.

Factory love to jack the pressure way up for the same reason that fuel injector manufacturers like Fuel Injector Clinic like it: It makes their fuel injectors look larger on paper.

thats why factories love 60psi and that is why aftermarket systems run 60psi out of the gate. Not for performance. Not for reliability. Not because it makes anything easier.
Just to make the injectors look larger so they can rate their systems for more power.

60psi sacrifices YOUR fuel system longevity and YOUR fuel pump flow rate and YOUR fuel system efficiency just so they can sell you a higherHP system on paper.

 

True, all new systems need tuning in every way. Which is why I already warned the owner it's not just a matter of connecting a couple wires and hooking up a fuel line.
I dyno tune fuel injection systems for a living. 6 days a week, and have been working with Delphi style systems since 2002 and other systems since 1994.
So your correct. I have little experience.
As It was stated before you came along. Fuel pressure could drop if the regulator was placed further from the throttle body. Perhaps this is true. But because the pump in these systems is running 100 percent of the time. This drop I have found to be unmeasurable. If your AFR's drop from 13.8 to 14.0 for a millisecond. No one will ever notice and no carburetor anywhere could ever be better.
Truthfully I don't care what Nissan does. In this case with a amateur installer. Keeping things within the design and readily available parts would be paramount.
The Holley system is designed to be run at 58 PSI. There intank pump with untank regulator is setup for 58 PSI. there base maps are certainly not perfect. But they are at least a starting point for the beginner.
Changing pressure would throw things way,way out.
Causing no trouble for someone custom mapping on a dyno. But wouldn't be at all helpful for our novice.
Yes sir, you can tell me I haven't a clue. That's OK.
Tomorrow morning at work I'll keep doing what I do.
And that's working with Delphi based fuel injection.

 

The C5, LS filter / regulator is at the rear of the car. Not near the engine.
Your correct. This system is clearly unreliable. Look how many LS systems are running all over the world.
Yes. I can lower pressure, and put in larger injectors to compensate. Or, not.

 

Thanks! For most LS-swaps into C3s I've seen (and many other classics) that filter/regulator ends up on the frame rail next to the engine. Not for the C5 itself, it seems.

I'm not sure the OP is willing to redesign the fuel system of the car. I suspect a solution that lets him bolt on things made to an existing standard (58 psi, for example), will get him on the road faster.

 

Exactly. That's the point I'm trying to drive home.
KISS.
Keep It Simple Stupid

 

GM vehicles run the 58 PSI system. As does Harley Davidson. These parts are readily available. Thus aftermarket companies run these systems with readily available parts. As per longevity. I'm thinking that the OEM's do think about that at least to a degree.
As a professional mechanic. I do not see many fuel pump failures. So, yes I have to think the OEM's might be on at least an OK track.
Nothing is perfect.
But let's give our novice advice he can reasonably work with.

 

Experience is meaningless. People learn at difference rates.

I have 25 years of experience and been doing this longer than you have. So there is also that. But like I said it is meaningless.

You SHOULD care what Nissan is doing. And Toyota. And all the others. In order to build a winning product and assemble a winning team you must ALWAYS be looking for information about what the other guys are doing.
There is only ONE grand design for an internal combustion engine design which is optimal and ALL manufacturers are working their way to the same end result eventually, ALL of the combustion chambers are beginning to resemble each other as ALL of the block stress design and so forth. To close your eyes what other people are doing is going to leave you behind, in the dust, as is evidence here you have been left in the dirt failing to ascend the knowledge tree to the ultimate design strategy. Failure to educate yourself in the optimal fluid pumping strategy. And make no mistake - air is a fluid. You've overlooked a set of massive universal rules which pertain to oil , air, water, fuel, that have to do with pressure and intended supply features. But I Digress! Lets not get into fluid mechanics just yet. You know that thing that I teach at university level.

Well sorry but you really do not. The Holley EFI has a self-tuning algorithm that novices rely on heavily. And there is a simple box which requests system fuel pressure. You simply put the correct fuel pressure into that simple box and walaa your precious "BASE MAP" is now suitable for use with any pressure. You seem to not understand this very basic tenant of EFI. And then suggesting that a dyno would be needed and 'custom mapping' - NOW its my turn to call bullshit. Absolute rubbish. The EFI contains self-learning Wideband oxygen sensor tuning efforts that will do the same thing on or off a dyno. Its up to the end-user to adjust those constraints and targets for their application and then finnesse the open loop basemap to achieve a smooth operation which blends with the closed loop which contains targets and a leash for future anticipated situations.

The amount of effort required in this way is THE SAME no matter what the starting fuel pressure is. rofl


What? You mumbled something.
Heres quick history. Back before auto-tuning was a thing, you know in the late 90's when widebands were just becoming affordable at a hobby level, there was no such thing as a auto-tuning software yet. Holley was EFI infancy. All we had was closed loop, nothing to tune the fuel map directly for us making changes while we drive.

So I imagined and invented one myself. My software is a sort of grandfather to modern day holley EFI auto-tuning algorithm which does the same thing 20 years later.
https://www.thirdgen.org/forums/dfi-...der-950-a.html

In 2003 I was doing something with an EFI computer on a level that you cannot currently perceive of, in a realm that you aren't even aware exists. Like the majority of 'car people' you are not the engineer who designed the EFI computer or its software and because of that missing information you are forced to rely on what other people tell you, and what the manufacturer recommends. Which is fine; your recommendation blends with everyone else so you look 'sane' and anything else looks 'wrong'. Which is why I am taking the time to correct you here now.

Just because something is different or new does not make it 'BULLSHIT'. If you are not an engineer with a sound logical mathematical reasoning for why your pumping fluid design or somebody else's is flawed then you should not speak at all. You should not assume that the manufacturer's recommendations for car parts is the only way or even the best way to use them. Lots of people buy car parts then modify those car parts as needed. It is not uncommon to modify a part you purchase for a performance vehicle. In this way we examine all modifications: Does it make sense. Does it have any draw backs. Does it etc... Don't simply immediately jump up and say "ITS BULLSHIT BECAUSE I'VE NEVER HEARD OF IT BEFORE'.

 

Agreed!

Does the EFI system come with an external (to the tank) regulator with a return line? Did Holley suggest that combination of parts, and if so, did they offer a suggestion?

You certainly don't want to eliminate the PCV. The single plane Holley intake I'm using has a bung at the back (not shown), that I'll use in a pinch. If the TBI TB doesn't have a port, does your intake? Perhaps use a catch can, too.

https://www.holley.com/products/engi.../parts/300-137

 

first off, thanks for all the responses. I figured out last night after posting this the "fuel system installation" chapter in the manual is the last chapter after the tuning section - weird spot for it. I had stopped reading the installation manual when I got to the tuning section thinking I was finished with the installation section.....

The kit comes with a bulkhead connection and parts to add a return line to the tank so that answers my question #1.

For question #2 - the Terminator throttle body has 2 full manifold vacuum ports - so I assume 1 for the brake booster and 1 for the PCV?

i feel I know what I am getting myself into with this project (we will see - lol). First project with EFI so learning as I go. I got the car pretty gutted at the moment doing a full suspension upgrade, differential rebuild, and trying to get the AC going again among a long list of other minor repairs and upgrades, so this will help with installing the fuel lines, harness, etc that is need for this to be done correctly.

 

Good on ya! Keep moving forward. Sorry for the bullshit in your thread. Keep it simple. It'll run great. Don't try to reinvent the wheel.
Cheers!