Ls swap 4.8 fuel question
 

I have 2004 4.8 ls swap runs but not well. I swapped throttle body's and MAF sensors. I replaced intake gaskets new plugs/wires and O2 sensors. Idles not great but does run. Returnless fuel system with the corvette style filter, and pump in tank. I decided to check the fuel pressure again and it pinned my 100 psi gauge. Has anyone else seen this issue with the filter/reg failing? I am sure it's connected correctly..

Re: Ls swap 4.8 fuel question
 

So just to be clear you using a C5 FFR with a return back to the tank? It's some what easy to hook up the inlet and outlet backwards.
Another problem that has come up is cheap C5 FFR's from unknown manufactures that are junk.
I would only use Wix or AC Delco FFR's purchased suppliers you trust. Not Amazon.

Re: Ls swap 4.8 fuel question
 

what fuel pump are you running? Anyting over a 250liter will over power a vette style filter.

and are you sure your gauge is correct?

Have you tuned the ECM at all?

What injectors are you using, is the ECM tuned to them?

obviously fuel psi is a concnern, but, there are more questions needed asnweered

Re: Ls swap 4.8 fuel question
 

Yes I am using the regulator filter with return back to tank. All hoses are new. Tank is new. i thought maybe I mixed up the return and pressure but double checked that. Filter/reg has failed. Yes it's a cheapie..Pins gauge so probably 120ish PSI

Re: Ls swap 4.8 fuel question
 

Fuel pump is the CPP 255LPH kit. Comes with the parts to cut a hole in the tank to add pump to tank

Gauge is new liquid filled I checked with another gauge as I couldn't believe it.

ECM programmed by Brendon at LT1swap.com Injector numbers given to him. he has tuned 4 for me so I trust him.

I will change filter/reg tomorrow, and we''ll see.

Re: Ls swap 4.8 fuel question
 

Haven't used the CPP 255 kit. But I'm guessing it's 255 Walbro fuel pump. I've used them on a number of LS swaps. My 98 Wrangler LS6/4l60E has used one for over 15 years and is still going strong.
Make sure it's a "real" Walbro.
I don't see how the tune will affect the fuel pressure. The injectors may be an issue but you have to get the fuel pressure down to 58 psi at the fuel rail.
What are you running for fuel injectors? Again fuel injectors bought on-line can be a total mess not unlike FFR's.

Re: Ls swap 4.8 fuel question
 

Fuel injectors are stock chevy..in the fuel rail when I bought the engine tranny. this is the 6th LS swap I have done and I have never had this much trouble getting them to run right. Getting another filter tomorrow so we will see..

Re: Ls swap 4.8 fuel question
 

I have read where not all of the filter/regulator type filters are equal. Some cheap ones out there that don't regulate properly.

Re: Ls swap 4.8 fuel question
 

On the used LS engines I've bought I've always sent out the injectors for cleaning and flow check. I know it costs a few bucks but it can save a lot of headaches as you get them running.
Yes there are any number of C5 FFR's made off shore that are junk but folks buy them anyway because they are half the cost of a Wix or AC Delco FFR.

Re: Ls swap 4.8 fuel question
 

Installed new FFR. Fuel pressure is now 59PSI from idle to WOT. Cut apart old filter (of course) and found a tear in the diaphragm.

Re: Ls swap 4.8 fuel question
 

Good to hear you got it sorted out.

Looks like a cool project.

Re: Ls swap 4.8 fuel question
 

agree.. glad things were "a easy fix" ...somewhat. I am having the opposite issue... I am running around 52-55PSI with a "knock off" corvette FP/Reg. I ended up buying a actual WIX BRAND regulator & with your post, I am now going to replace it with the name brand one. I guess I am stubborn (& old fashioned) & still believe that new products should operate correctly! hopefully like you, the filter is my issue...:ito:

Re: Ls swap 4.8 fuel question
 

Normally a chevy guy. But this one kinda fell into my lap. Crown vic swapped it and added the LS 4.8/4L60E..should be a good driver.

Re: Ls swap 4.8 fuel question
 

Glad you got it figured out.
I had the same problem with my 80 Camaro project with a LS3 swap.
Bought two AC Delco? FFR's off a forum I won't name because they were 1/2 the cost. Both were 75-80 psi at the fuel rail. I asked the seller for a refund and I would send them back to him on my nickel. Never heard from him again. He vanished off the forum.

Re: Ls swap 4.8 fuel question
 

I have a brand new regulator with a high output pump and the pressure is at 50 psi using a snap-on gauge. It is giving me no issues but I have some CNC heads to install. I was planning on changing out the regulator to a WIX one to see if I could get the pressure to 56-58 psi.

As consumers we are now product quality control.
My pump came wired backwards and because of this it sucked LOL. Had to drain the fuel and drop the tank all because someone couldn't insert the correct color wires in the right holes.
My guess is it's less expensive to just replace the defects than have a proper quality control department.

Re: Ls swap 4.8 fuel question
 

accelo, agree with you, I believe it is now (has become) cheaper to re-send replacements then to spend "more time" doing QC :(. I had a AC DELCO tank selector switch shipped that actually had no "toggle switch" it was just a the surrounding casing (undamaged sealed box and shipping box was not damaged or looked abused) :cuss: of course I just sent it back and in 2 days I had a "good" replacement in my hands. I think that "millennial thinking along with not my job thinking" is the normal now......

WALL-E here we come!!:dohh:

Re: Ls swap 4.8 fuel question
 

im in the same boat kind of 04 4.8ls swap runs like poo, intake gasets mas flow, system lean codes 53psi at idle, drops to 40 psi with ac delco pump and vette fitler, guess im changingt he filter frist and praying or may change both filter and pump since i got to lift the bd off to get tot he filter

Re: Ls swap 4.8 fuel question''AN UPDATE."
 

Finally got this unit to run correctly.
Chinese harness off ebay the map sensor was wired to 12V instead of 5v should have been pin 47-C1.. Took out the map sensor. Removed harness and checked every wire to make sure they were in the right spots...(if you google ebay LS swap harness lot's of info)
Anyway ran better but still ran like poo. I had already tried the throttle body off my 72 K10 6.0 so I picked up a junkyard intake. Changed it out and voila! runs as it should. The crackhead I bought the motor off must have dropped it on the intake as it had a crack that you couldn't see from the outside. But with a light on the inside it was clearly cracked. Thanks to all for input. Here's another picture.