Those running stock fuel pumps...
 

Hey guys, just thought I'd let you know about my recent "holy crap" moment! I am running the Maggie TVS 2300 (3.8 pulley) with LT headers, high-flow cats, CAI Inc intake and Borla S-Type exhaust. THANK GOD I have the master (Mr Jannetty) tuning my car. I noticed some slight "surging" the other day at very light throttle. While I didn't think too much about it, I contacted Ted and he asked me to send him a data log so he could fix whatever was going on. I took my lap top, went for a cruise and sent him a low speed and a high speed data log (SCT) so he could take a look. I am only running around 6.5 lbs of boost with this 3.8 pulley and I am (as the title says) running the stock fuel pump. Ted immediately noticed that I am running dangerously LEAN once I get above 4500 rpm!!! NOT GOOD. This is nothing that he can tune for since my stock pump is simply NOT keeping up. Also keep in mind that my AFR is right where it is supposed to be (11.5:1). This is where I was missing it! I assumed that just because my AFR was dead on that my fuel pressure must be good? UMMMM, NOPE!! My poor LS9 injectors had to work near their peak (duty cycle) just to keep up. Thank God I didn't hurt anything! Needless to say, my ZL1 fuel pump and ADM controller are already on the way. I just thought that I'd share in case anyone else out there is in my situation. This is still a learning experience for me, but between this forum and Ted, I feel like I'll get 'er dialed in.

Thanks guys!

If your AFR is 11.5 how are you running lean?

My fuel pump was not keeping up with the proper pressure, so it forced my LS9 injectors to work overtime! I'm far from an expert on the topic, but when Ted tells me that I'm running "dangerously low fuel pressure", I gotta listen! ;)

What was the fuel pressure and injector duty cycle?

I can only tell you the fuel pressure that the SCT data log showed. I'm not sure what the unit of measure is but according to Ted, its supposed to be holding steady at around 130. I was falling into the 70's at rpm's above 4500!!! He said that my duty cycle was close to maxed out but I didn't ask the exact percentage? To be honest, it really didn't matter to me at this point. I quickly ordered my new ZL1 pump and ADM controller.

Ted just told me to multiply my 133 number by 3 to get my kpa reading. 400 kpa equals approx 43.5 psi. When my numbers fell off to 77. That was around 19.5 psi. Not good!!

I am also trying to grasp the concept of a good AFR and being able to maintain a good AFR with low pressure. I run nitrous on a stock fuel pump so I need to know this. OP can you post more info if you get it on how this is possible?

The only thing that I have found out about my situation is that my low fuel pressure was forcing my injectors to work near their peak duty cycle. Once I install my ZL1 fuel pump and ADM controller, my injector duty cycle will come back down. You might want to contact Jannetty directly for your situation. I don't pretend to be an expert guys, I just wanted to make you aware of the potential dangers of our stock fuel pump on FI cars. I was under the impression that my stock fuel pump would easily be able to keep up at my HP level. That was not the case!

Didn't need the ADM component, but you have it already... Swap out injectors now and turn up the boost haha!

The ADM controller gives Ted more freedom to 'play' and after what just happened, seems like cheap insurance? Oh, and I am installing my 3.6 pulley. Gotta make the most of the situation, right? Hopefully I can manage a mid 11's in a few weeks at the track. That would make me very happy. Simple pleasures. ;)

How much HP can the ZL1 pump handle?

Im at 600rwhp on a mustang dyno probably around 650 on a dynojet, with zl1 pump and adm fpcm

Confused, if afr is 11.5 throughout the run, how can that be lean? I understand if the fuel pressure drops, the injector duty cycle would need to increase. Why wasn't this seen when you 1st had the car tuned? Or did you load a canned tune or have a different shop tune it? Surging at only light throttle sounds like something else since, I would think, the stock fuel pump should be able to keep up under light load. So, not sure if the surging would be due to fuel pressure. Quite possible surging is a tune problem and that the fuel pressure was observed to be dropping as well. 133kpa should be at idle on sct livelink2, multiply by 3 and then convert to psi. 400kpa=58psi. So 70kpa, 210kpa=30psi.

I have been over 600 rwhp for 7,000 hard miles without any issues this summer, and I don't use a ADM controller with my ZL1 pump. Car runs great.

I suppose if the duty cycle of the injector is maxed out, the fuel system would be dangerously lean? Again, far from an expert here guys. I just wanted to alert some of you of the potential issues with the stock pump. My advice would be to connect with Jannetty about your specific situation if you think you "might" be running lean? The "surging" really had nothing to do with running lean as I have plenty of fuel pressure under 4K rpm, it was the initial reason that I sent Ted my data logs, which turned out to be a good thing I did!

I am not an expert either I am not sure that lean is the correct word but what I think OP is getting at is that his AF reading although was good and "safe" his fuel pump was maxed out so much that he was losing fuel pressure and his injector duty had to increase a lot to keep up and causing a potential unsafe situation thus causing him to go with the ZL1 set up. Me also being fairly nube to this and learning think there is more than just AF to consider when building/tuning a car and wanting to be safe presssure is just another one of these items that you should consider. Please if this is incorrect correct me I take no offence to learning and being corrected.

Ted told me that the ZL1 pump should be able to safely handle around 650 rwhp when I asked him the other day.

Not exactly sure where you are getting this kpa to psi conversion from? I have attached the conversion chart the I received from Ted. 400 kpa equals 43.4 psi according to this chart.

I am also a little confused on how the conversion works as the normal conversion for kpa to psi is different from above. It is what Badbubba posted if you just do math but maybe there other others factors when you deal with car fuel pressure, not sure how the above chart reads.

The Chart seems to show the conversion from kpa (eg map) to psi incorporating the usual barometric pressure of open air (100kpa or 15psi or 1 bar)

Geez, I feel like a nerd now:bonk:

What he said!!! All is I know is the chart came from Jannetty, and I know better than to question the master. HA!

So the chart is subtracting 1bar, 14.5 psi. Thus stating that the 58 psi is absolute pressure and not gauge pressure. I disagree that this chart is for our application. If a mechanical fuel pressure gauge is attached to the fuel rail, it displays around 60 psi iirc. I bench tested and set my fuel pressure safety switch for 45psi gauge pressure. If the chart is correct, I would never be able to activate my N2O. Or am I missing something? The chart doesn't represent your 6.5psi boost "pushing back" on the injector fuel pressure either. Just trying to understand.

That chart is for boost reference.
Fuel pressure is different. You don't deduct 14.5 psi or 1 bar or 100 kpa from what you see.
In fuel pressure what you see is what you have. 3 bar is 43.5 psi. 4 bar is 58 psi.

Yep.

A properly programmed ZL1 fuel pump controller / ADM is necessary to get the maximum efficiency from a ZL1 pump installed in a non ZL1 Camaro.

:pop2:

This is what Jannetty said as well.