LS swap fuel system

[KennedyHill]

I am currently working on a 5.3 LS swap in my squarebody. I have a question on the fuel system. I think I have what is called the “truck intake.” It’s the big ugly one.

The fuel rail has an inlet and return and I’m assuming it also has a fuel regulator built into the rail. It has a vacuum line going to it from the top of the intake.

Here’s my question: should I use the existing regulator or would it hurt for me to have another aftermarket regulator mounted to the frame?

I was thinking I could run a pressure line to the inlet on the rail and plumb the return side of the rail to the new regulator and send a return from the new regulator to the tank.

 

[SquareRoot]

Use one or the other, not both. The best setup is having the regulator on the return side of the rail. I have aftermarket (Edelbrock PF-4/ Aeromotive) setup and that's the way they say they like it. Check out Aeromotives website, they have some really good info.

 

[Hunter79764]

Yes, run the factory regulator on the rail.
Most people think that the "returnless" style is better because it is newer, it isn't. It just saved GM some money by putting the regulator in the tank on all of the trucks, which is good enough to get them through the warranty period. The regulator should always be as close as possible to the fuel rail to account for any type of system imbalance. The "Corvette regulator/filter" is a decent option if you are stuck doing returnless for some reason, but it really just shortens the length of the return line by the same distance you move the regulator away from the fuel rail. Not a good option if you can avoid it. Vacuum referenced regulator on the rail is also better if you ever boost it, within reason.

 

[KennedyHill]

Yes, run the factory regulator on the rail.
Most people think that the "returnless" style is better because it is newer, it isn't. It just saved GM some money by putting the regulator in the tank on all of the trucks, which is good enough to get them through the warranty period. The regulator should always be as close as possible to the fuel rail to account for any type of system imbalance. The "Corvette regulator/filter" is a decent option if you are stuck doing returnless for some reason, but it really just shortens the length of the return line by the same distance you move the regulator away from the fuel rail. Not a good option if you can avoid it. Vacuum referenced regulator on the rail is also better if you ever boost it, within reason.

Thanks for the advice! After doing a bit more investigation, most people say the factory regulator is the way to go! Good to know. Thank you sir!

 

[Camar068]

I am currently working on a 5.3 LS swap in my squarebody. I have a question on the fuel system. I think I have what is called the “truck intake.” It’s the big ugly one.

The fuel rail has an inlet and return and I’m assuming it also has a fuel regulator built into the rail. It has a vacuum line going to it from the top of the intake.

Here’s my question: should I use the existing regulator or would it hurt for me to have another aftermarket regulator mounted to the frame?

I was thinking I could run a pressure line to the inlet on the rail and plumb the return side of the rail to the new regulator and send a return from the new regulator to the tank.

as much as I hate to say, I wish I had installed an external fuel pump. This way in the future, when in doubt you can get to it easier to swap. Just a thought on where you're at right now. Also put it where you can get to it easily.

I put mine in the tank so "it wasn't so loud" as most say. Had I thought....can you hear the pump run when ur driving down the road?....No.

 

[Hunter79764]

It is sort of a trade off cycle. Pump mounted external makes it easier to mess with wiring and/or change out, but it also makes it more likely to have to mess with wiring or change it. Internal pump is much happier, and should get you 100k miles pretty easy, and for most folks doing a swap, that's a lifetime. Obviously, if you are running a super pump and 25 lbs of boost, no pump will live as long, but in tank will always live longer than external.

 

[TotalyHucked]

as much as I hate to say, I wish I had installed an external fuel pump. This way in the future, when in doubt you can get to it easier to swap. Just a thought on where you're at right now. Also put it where you can get to it easily.

I put mine in the tank so "it wasn't so loud" as most say. Had I thought....can you hear the pump run when ur driving down the road?....No.

No you don't. I see external pumps fail left and right, in tank is the most reliable hands down.

 

[Bextreme04]

Yes, run the factory regulator on the rail.
Most people think that the "returnless" style is better because it is newer, it isn't. It just saved GM some money by putting the regulator in the tank on all of the trucks, which is good enough to get them through the warranty period. The regulator should always be as close as possible to the fuel rail to account for any type of system imbalance. The "Corvette regulator/filter" is a decent option if you are stuck doing returnless for some reason, but it really just shortens the length of the return line by the same distance you move the regulator away from the fuel rail. Not a good option if you can avoid it. Vacuum referenced regulator on the rail is also better if you ever boost it, within reason.

It has more to do with flex fuel and pump design. The newer stuff is PWM controlled and doesn't have a "regulator" at all. It is a returnless system that uses a fuel pump control module, PWM, and a fuel pressure sensor to keep the inlet pressure where it wants it at all times. My 2011 Suburban has 240k miles on it and never had a problem. I don't know that I have ever heard of anyone having them fail like the late GMT-400 trucks and early LS trucks with a return line system had all the time. You pretty regularly hear about them losing pumps or regulators. Mine runs 45PSI during most regimes because it is flex fuel and has the bigger injectors to support that. If I run E85, it will bump it up to 56-58PSI automatically. It is the same fuel pump module and controller that is used in the CTS-V, so if I ever slap a supercharger on it... no changes necessary. It is actually a more expensive system than the return line system, but it became cheaper for GM to do because they could basically use the same module in everything and then just adjust the programming for the specific application.


I would personnaly run an EP381 pump in an 87 TBI sending unit. Plumb your lines just like a stock 87 Truck. Use the stock regulator.

If you want adjustable FPR, you need to block off the regulator in the rail and then just plumb in the aftermarket regulator to the return line.

ICT Billet makes a nice plug for this: https://www.ictbillet.com/fuel-pres...s-plug-for-ls-truck-intake-manifold-rail.html

This plug also fits the L29 Gen VI 454 fuel rail and lets you delete that garbage FPR that is always failing in them. I'm running one on my swap L29 with an external aeromotive adjustable FPR.

 

[Hunter79764]

It has more to do with flex fuel and pump design. The newer stuff is PWM controlled and doesn't have a "regulator" at all. It is a returnless system that uses a fuel pump control module, PWM, and a fuel pressure sensor to keep the inlet pressure where it wants it at all times. My 2011 Suburban has 240k miles on it and never had a problem. I don't know that I have ever heard of anyone having them fail like the late GMT-400 trucks and early LS trucks with a return line system had all the time. You pretty regularly hear about them losing pumps or regulators. Mine runs 45PSI during most regimes because it is flex fuel and has the bigger injectors to support that. If I run E85, it will bump it up to 56-58PSI automatically. It is the same fuel pump module and controller that is used in the CTS-V, so if I ever slap a supercharger on it... no changes necessary. It is actually a more expensive system than the return line system, but it became cheaper for GM to do because they could basically use the same module in everything and then just adjust the programming for the specific application.

On the newer stuff, you're right, they are much smarter and you gain a lot of flexibility. The earlier returnless was more what I was referring to, where the fuel pump module had a regulator built in, and the "return line" was about 6" and part of the assembly, never leaving the tank. 58 psi left the sending unit, and that was the last place there was control.
I think the PWM stuff has a fuel pressure sensor that can adjust the pump to make sure it has the right pressure for the situation. In that sense, it is essentially an electronic regulator at the rail.

I've replaced a number of in tank fuel pumps, older ones (80's and early 90's) we did preemptively at around 100k, the 2000's stuff has gone ~250k no problem for me, usually replaced for a tangential reason like gauge failure or leaks. I did have a suspected regulator fail on our old 2001 at about 300k, but it might have ended up being a dirty fuel filter? It was 10 years ago, memory is fuzzy, but I know I bought one. I don't have any experience on the newest gen stuff, at least not yet.

 

[Camar068]

No you don't. I see external pumps fail left and right, in tank is the most reliable hands down.

Thanks for the reminder. Been a while since I've thought about why I went in tank.

@KennedyHill don't want you to miss this reminder for me.

 

[Camar068]

No you don't. I see external pumps fail left and right, in tank is the most reliable hands down.

What make/model pump are dependable these days? I put in the ACDelco EP381 and they want $160+ for it now.

[edit] this was added to a 87 burb sender/tank

Little hijack, sorry OP, but it's for your benefit as well.

 

[TotalyHucked]

What make/model pump are dependable these days? I put in the ACDelco EP381 and they want $160+ for it now.

[edit] this was added to a 87 burb sender/tank

Little hijack, sorry OP, but it's for your benefit as well.

My tuner swears by the EP381 but I have a Walboro 255 in mine now. I had 4 EPs fail but I eventually found that the little plastic piece in my pickup sock was coming apart and sending shrapnel through them, so it wasn't their fault. But I've always used Walboro in the past in anything I put a pump in and they've all been great. Just make sure you're getting a genuine Walboro, there's alot of ripoffs out there. I'll see if I can find the link to where I bought mine, my tuner sent it to me and they promise genuine pumps