Fuel Pressure Help PLEASE!!

[dan0617]

ECS Vortech Si kit, 11.5 psi boost at 6100 rpm auto shift point. L99 with stock cam, LT headers, catless mid pipes.

Fuel system is ZL1 pump, ADM FPCM, and -6an fuel crossover line. Ted Jannetty tuned for FPCM. Fuel is 10 to 12% ethanol 93 octane.

I had in 52 lb ZR1 injectors. Fuel pressure jumped up at 4000 rpms as commanded, then fell quickly down to about 51 psi at about 5200 rpms, then stayed there till redline (6300 rpms).

Ted said I needed to upgrade to a twin pump setup. Andy said it is likely dropping because the injectors were nearly maxed out, and anything over 80% duty cycle makes it very hard to maintain fuel pressure. Matt at FSP kind of thought Andy was right and ID-850's would fix it. I know the twin pump would give plenty but I'd still be nearly maxed on injectors, so I thought I'd change them out.

Well, below is the new datalog. Ted is just beginning the tuning so it is rich (AFR in the high 9's and low 10's the whole way) but the fuel pressure is still dropping down. It now goes up as commanded at 4000 rpms, then prettymuch steadily drops down to about 51 psi. Staying higher for longer with the larger injectors, but still steadily trails down. Analog1 is the wideband, yellow line is fuel pressure (take number times 3 for kpa). Frame is at 6100 rpms.



Why does everyone say the ID-850, ZL1 pump, ADM FPCM combo holds pressure to 650 rwhp when mine is less than 550 rwhp and pressure is still falling down???? Anyone have any idea what I can do short of changing to a dual pump setup? Andy, if there are other parameters that can be entered that will help me other than what Ted would already have, please send them to Ted for me! I have all the money out that I can put out right now, no twin pump in my future.Already bought ECS kit, fuel pump, control module, tune fee, headers, mid pipes and 2800 converter this winter. I want to be done spending for many years.
I realize I have plenty of injector and am plenty rich still so it is getting enough fuel, but why is the pressure dropping still???

I should add, this is a fairly high boost setup....11.5 psi at 6100 rpms. I ran it out to 6300 rpm redline once and saw 12.4 psi. Won't be going that high ever again as I always auto shift. I added the wideband into the datalog stream so Ted can dial it in right on but on the safe side. I've always been a believer of running the boost up higher than most to make the power but keep the AFR and timing on the safer side.

I also have nitrous on the car and hoped to work up to a 50 or 75 shot. I will for sure have to start very low and watch the fuel pressure and AFR. Since it is trailing off now I'm not sure if a small shot of nitrous will make it trail off more and the injectors will make up for it, or if fuel pressure will nose dive. Time will tell I guess.

Should also add, Andy, Matt at FSP and Ted have all been great with putting this setup together and giving me advice. Ted put the tune very close and on the safe side to begin tuning in on the first try.

[2012REDSS]

Mine does the same and I'm at 12 psi at 6200. My afr looked great on the dyno but I'm sure I'm pushing the limits of the 66lb inj that vortech supplies and the zl pump even with the adm Fpcm. Ted also tuned my car. Is the general consensus that the zl pump and adm Fpcm is good for 650 hp on manual cars?

[dan0617]

Thank you for the reply, Guess I'm not the only one.

I am an auto and don't know for sure what my RWHP is, the standard Vortech Si trim at 10 psi is like 525 RWHP on an auto. Since I'm at 11.5 I'm guessing I'm pushing 550 rwhp. I figured that would be like 600 if it were a manual.

Maybe it is just maxed out. Wonder how much a BAP would help?

Is the fuel pressure shown (take the number times 3, that is kpa, it's about 51 psi) is that what is in the rail, or is that already figuring on the boost (as in, is my effective pressure at the injector tip 51 psi, or do I take the 51 and subtract 11.5 due to the pressure in the intake??)

Does it matter alot that fuel pressure is slowly declining since I now have plenty of injector to open up more as the fuel pressure declines?

Wonder how bad it will be when I hit a 50 or 75 shot in the future?

I'm just full of questions and hope someone can answer some of them for me.

[2012REDSS]

From what I've read the fuel pressure is read at or close to the tank however there was a thread not to long ago saying fuel pressure was measured at the rail and was almost dead on with the reading from the obd2 port. That's about the extent of my knowledge but I'll be watching to see what others post.

[Chris82xx]

That was gonna be my question to you, was if you were running a BAP. It would help out a bit. Before I switched over to a twin pump, I was running a stock pump, BAP, and 65lb injectors at 684rwhp. Keep in mind though that the NOVI 1500 is equivalent to a T-trim. If somehow you can find bigger injectors on here for a good price, grab them. Those in combination would help significantly.

[dan0617]

Originally Posted by Chris82xx

That was gonna be my question to you, was if you were running a BAP. It would help out a bit. Before I switched over to a twin pump, I was running a stock pump, BAP, and 65lb injectors at 684rwhp. Keep in mind though that the NOVI 1500 is equivalent to a T-trim. If somehow you can find bigger injectors on here for a good price, grab them. Those in combination would help significantly.

I'm already running ID-850's.

At 684 rwhp was your fuel pressure dropping down?

[Chris82xx]

Not that I know of. What was happening with my was that at WOT, I was maxing out the pump and injectors. Pretty much starving for fuel. I would do the BAP. It's not costly, and it will help you out. There was a car that ran a BAP with the ZL1 with the 850's and he was making nearly 800.

[dan0617]

If I try that, what works best with the ZL1 pump and ADM FPCM, the Kenne Bell boost a pump, or the MSD fuel pump voltage booster?

[Chris82xx]

I had the Kenne Bell. My personal opinion, it's comparing apples to oranges. The reason I had the KB, is because that is what was sold with the kit. No one on here really complains about either one of them, so get the one that has the better deal on it.

[Iam Broke]

Originally Posted by dan0617

If I try that, what works best with the ZL1 pump and ADM FPCM, the Kenne Bell boost a pump, or the MSD fuel pump voltage booster?

The MSD FP booster from JRE. Support the sponsors.

[realsquash]

FYI the fuel pressure is not measured at the rails, the sensor is located next to the fuel tank. In reality that doesn't make much difference in what pressure you see at that sensor and what you should see at the rails on the stock setup. There's only one fuel pressure sensor on the car from the factory.

The ZL1 pump is a 255 lph one vs. 190 lph on the SS IIRC. Not much of a difference but if you're running at the limit just a little bit can make all the difference.

[VanquisherSS]

Originally Posted by dan0617

Wonder how bad it will be when I hit a 50 or 75 shot in the future?

I'm just full of questions and hope someone can answer some of them for me.

We'll my setup will be very similar to yours but I have meth injection, smaller injectors, and I will be spraying 100shot. ECS is finishing my car up now I'll let you know how it goes. My car is a 6 speed but it should give you an idea.

[dan0617]

Well, as Ted works the tune and I datalog, things are getting much better. Below is a new snipit. Did a full WOT pull from 25 mph to 133 mph. Fuel pressure stayed way up, 63 psi or over!!!

I'm assuming it is because it was so rich, we leaned it out and pressure is fine, even though we are still at upper 10's on the AFR. About 11.2 is what we are looking for since I run 10 to 12% ethanol. I'm amazed that leaning it out from upper 9's AFR made so much difference on the fuel pressure. That, and boost came down from 11.6 to about 11.1 due to being 50 degrees out instead of 40.

Ted is still working on a couple little things but tune is close. AFR is pretty steady in upper 10's, just a touch of knock retard here and there, etc. Car pulls HARD up top. I'm very happy at this point. Hoping Ted will bump my WOT shift point up from 6100 to 6200. He is the man for quick tune changes and getting it dialed in with only a few datalogs and tune attempts.

The fairly flat tan line on the datalog is the AFR. I have a firewire cable set up to my Innovate LC-1 so we can see AFR on the datalogs.

[JANNETTYRACING]

Fuel pressure is a product of what the fuel pump can put out VS what the engine is Consuming.

This is why as we reduce the fuel consumption (AFR) the fuel pressure rises.

This Shows How Close to Max the ZL-1 Pump Really is, There is Little room for Error.

Also I an not Surprised the ID850 injectors Improved the fuel pressure, I have seen this many times and have posted about it.

Here is Why!

With larger injectors, you have More Close time between injector events which in turn allows the pump to catch up a little.

I still recommend the Twin pumps over 550 RWHP Auto and 600 RWHP Manual.

The ZL-1, MSD, ADM Combo costs just as much and is only Slightly better than the Stock pump, like 50-75 RWHP.

Ted.