should this work the same for a hellcat/ 535LPH pump?

 

Hey guys,

I know this thread isn't exactly current, but Im hoping to do this swap with the 525 pump as well because my factory flex fuel pump just went out. I have the 525 pump in hand (truck will have turbo very soon.) and Id love to not have to buy a $300 OEM Flex pump to use it only for a few weeks.

My 2007 NNBS does not have an FPCM, do I also need to run my new -8an feed line, fuel rails, inline fuel filter and fuel pressure regulator at this time? Or will the truck adjust voltage to adjust the fuel pressure on its own?

 

I don't know this, but if you in fact don't have a FPCM, I believe the ECM has the capability to duty cycle the fuel pump. It has duty cycle tables in my 2011 L9H 6.2 Denali, but they don't look like they were really "tuned" of course since mine has a FPCM. I would think the ECM could also sense fuel pressure from a pressure sensor wired to it as well, so then it could determine the correct duty cycle to run the pump. That is the same thing we are doing here we are swapping pumps and the FPCM in theory should use the fuel pressure sensor to find a new optimal duty cycle with this new higher flow (assuming higher current draw pump) which would mine once you put the higher flow one in the duty cycle should automatically go lower.

Not sure if its in your OS, but under the "system" tab in HP Tuners there should be a "Minimum Fuel System Voltage" table, which has on the row axis has some unnamed random values from like 0 to 70 something, which I am assuming this is just some undefined unit of fuel flow like the other tables use. The column axis is intake air temp (no idea why they choose to base it off IAT but the stock values don't change with IAT anyway). The values in the table are voltage values that the ECM will try to target when at the fuel flow rate. So when there is high flow demand on the pump the ECM should boost the voltage output on the alternator. I've tested it and it works on my truck, but it has a limit of around 15 volts so you can't get much out of it. Problem is when I boost the voltage on mine something else in the FPCM makes the stock pump duty cycle go down again and cancel any "gains" out.

I think people go way overboard and blow a bunch of money on all these fancy looking braided stainless lines and fittings, I don't think there needed unless you are running and extreme amount of power.

 

I was wondering how the OP connected his pump to the grey part inlet that has the o-ring over it as well. They are all different sizes:





How is your barb fitting holding up? I guess its brass? I am paranoid I am going to do something like that and put my pump back in and think its ok, but then over time something unexpected happends and fails or cracks or something or leaks and then I get stranded unexpectedly.

 

So I ended up trying to do something like this and after trying to get it back in the bucket and get the venturi line thing back in I just gave up and decided I would just go no straps holding the pump in at all:


So it seemed to be secure once everything was stuffed back in the bucket and the plastic snapped together, minimal rattleling, but I just couldn't figure out a better way to get the awkward shape pump secured in the bucket.

I think I am still more worried about the fuel line coming off the small little boss (the one Mean Green Z28 threaded a brass compression fitting onto with a nipple, which is probably what I should have done as well). I just heated up my corrugated hose and put a little chamfer on it and pushed the hose up on the boss as hard as I could, then put a stainless steel hose clamp over it and tightened it as hard as I could as well, which could be over tightened:



So when I went to drop my modified bucket and hat back in the tank, I realized my top bosses that hold the metal sliding rail things were broken. When I bought the truck I thought it had a bad fuel pump and when I took the fuel pump out I found it sideways laying on the bottom of the tank and nothing holding the bucket to the hat besides the electrical wires. The truck was hit from behind in the trailer hitch so all the impact went straight to the frame and apparently straight through the frame to the hat on the fuel pump assembly and jerked it so much it snapped the plastic bosses off. I imagine it was probably worst case scenario where the tank was almost empty and the bucket was full of fuel so it had a lot of inertia and the cheap plastic couldn't take the load. So I bought a brand new GM/Bosch assembly and dropped it in. The one I modified above is my original old one:


So after all this work I wasn't going to let this defeat me, so I put one of the metal sleeve rail things in a third unused boss, and I drilled out the broken one and heated it up a little with my heat gun and put the other metal sleeve/rail thing in it and tapped it in as best I could with a hammer:


So it seemed to be somewhat sturdy, maybe not as stiff as the new stock one I bought. I am still extremely paranoid its going to break off or the fuel hose line is going to slip off the plastic boss since it doesn't have any barbs on it. The fuel line hose seemed to be on there pretty good as well and you couldn't pull it off by hand. If these plastic bosses break holding the sleeve/rail things that's one thing, I think the truck would still run it just might die in certain situations like at idle (that is how it behaved when I first bought it when the bucket had broke off from the hat and was laying sideways in the tank). So I could at least maybe still get home.

If however, the fuel line slips of the plastic boss I am definitely screwed since it won't pump and I will lose pressure instantly. I guess I can always try and keep thinking of something better and pull the bed and pull the pump out and fix it again.

But still bad news, when I logged it, it didn't seem to have any more fuel pressure than with the stock pump. I am hoping it just needs to learn the trims. For whatever reason the actual fuel pressure is clearly 25 psi under the desired fuel pressure but the pump just won't command more duty cycle to make it meet demand.

 

I just read the tune file on a 2013 Sierra Denali and it came up as calibrated 13-15 CTS-V from the factory. I didn't read the FSCM itself because I'm
just getting started on having the ECU tuned with a file from Magnuson but I expect I won't have to touch anything in the tune as far as FSCM tuning. Correct me if I'm wrong.

 

Mine does the same thing, I think that is normal just because maybe that's the platform HP Tuners started off to get support for the FSCMs. I believe they are a very similar controller to what's in the CTS-V's. Unfortunately we can't write the entire calibration, which is what we need to be able to do to get the "hidden" better stuff that the CTSV/ZR1/ZL1 calibrations have.

 

Curious on where you got the larger gauge wire fuel hat fitting and wire from? Is it an oem part or a aftermarket part

 

An excellent company called Racetronix.

wire you need is
https://www.racetronix.biz/p/in-tank...css-8/itwh-029

Bulkhead connector, I had bought the wrong size so I ended up using the stock one, which has some pretty robust wire attached (not removable it's soldered in) the stock wire seems larger diameter than what Walbro pumps have on them so not really sure you would need the larger bulkhead connector upgrade. I had researched the stock Bosch pump and from what I found is that it's current draw is in the ballpark of the Walbro.
With that said I bought the 028 bulkhead connector part number and it was the wrong diameter, I think I needed the 027 part number:
https://www.racetronix.biz/p/connect...80-150/rcs-027

 

mannn, I’ve already got a heavy shopping cart built up from there for this project lol I’ll try a 027 and update if it fits. Thanks bud