Aux fuel pumps - not that good! - Page 2 - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

eLeSthree · 06-03-2020, 09:36 AM

Quote:

Originally Posted by Juiced1

It's all in the tuning. The stock FPCM need to be tuned otherwise the pressure will drop. Anytime you add a aux pump on the 5gen tuning is required.

FPCM was tuned by mr D Steck (DSX) himself. There are simply mechanical limits to these systems. Running straight E80, with 950 crank horsepower plus whatever my blower was eating up, the limit was found.

Does Juiced have cars with Aux pumps making over 850whp on E with zero FP drop???? I dont think so.

dookie454 · 06-03-2020, 12:01 PM

Aux Pumps are puller pumps (pulling through lines from the tank), or inline with in tank pumps, both don't work well at higher flow, not because the pumps cant keep up, but because the suction side is the restriction. Whats worse is they can start to cavitate without you knowing, even if pressure is ok. In the case of the Aux pump pulling fuel from the tank, that suction side hose is the restriction. In the case of inline aux pump, the in tank pump is the restriction..once it starts dropping pressure, you start to starve the aux pump.

In tank pumps are pusher pumps, which is what you want, just larger or more of them. They minimize, or remove the suction restriction, since they are submersed, which is key. However with the larger or addition of in-tank pumps, you need to have a way to modulate (slow down) all that pump with dead head system, then run wide open for max HP, this is easier to do with a return style setup.

I know this since I've had many a problem with this, one was a simple remote mount large pump, pulling fuel from a hose going to the tank from the top, to the bottom of the tank. It worked well most of the time but it would start to cavitate during the highest of flow demand.. creating all kinds of weird side effects.

Rem0v3r · 06-03-2020, 03:22 PM

I have elesthrees old aux setup and run 75% ethanol full time.1000cc.. I'm currently building my motor with forged goodness and a tsp turbo stage 2 cam..
I fully intend on finding the limits of this fuel system once my car is back together :-)

JackLS1R1 · 06-08-2020, 06:32 AM

Quote:

Originally Posted by eLeSthree

It was this one.

https://www.lingenfelter.com/product...l#.Xtd5lTpKiUk

I saw more pressure when it kicked in, but the FP still tapered off some. It's not the stock feed line, because many have used that up to 1100whp and beyond. I'm guessing it must have to do with sharing the feed line with the in tank pumps. Maybe there is some type of internal regulation going on inside the tank and pressure bleeds back into the bucket. I dont know, but I gave up and went triples.

Thank you. After posting this I figured the upgrade over the stock aux pump Walbro 255 would be a Bosch 044. This Lingenfelter one is interesting, but expensive.

My FPCM is tuned and still seeing the pressure drop.

I do agree there has to be an issue with that 3rd external pump in the system causing flow disruption issue when using the stock line.

Rem0v3r · 06-23-2020, 06:46 PM

Dont get hung up on fuel pressure too much with the aux pump.. your ecu calculates the pressure delta between the fuel and the air and delivers the correct amount of fuel.. you need a specifically high pressure delta to maintain a good spray patturn..

In short.. stock is 58psi.. if your aux spikes the pressure to 85 and it drops down to 74.. but your only pushing 15psi boost.... it really doesn't matter...

If however you only got 40psi fuel pressure.. you got problems.

98camarozzz · 06-24-2020, 09:15 AM

Quote:

Originally Posted by Juiced1

If you guys are trying to run 850-900rwhp with E85 you need a legit dual or triple in tank set up. We have taking the Squash dual pumps past those numbers but if you're eyeing 1000rwhp on E I'd go with a Fore triple.

Not true. Zl1 here with an aux that I modified. 1088whp currently and rock hard 58psi Bosch 210s and e85.

Ditch the -4 line the kits come with. -8 Y off your regulator to Two -6 lines. Weld -6 bungs onto the front of your rail.

John_C · 06-24-2020, 11:00 PM

I have the same issue.

Car makes 760 rwhp with 13 to 14 psi at 6,800 rpm's and fuel pressure drops.

ID 1300X injectors
DSX Auxilary pump.
DSX Flex sensor
ZL1 in tank pump

Rem0v3r · 06-25-2020, 03:40 PM

I've been kicking around the idea of dual aux pumps..
Keeping it returnless, zl1 pump upto 1kpa my aux pump kicking in till wherever the limit is... then a 3rd pump on a seperate line , check valves, direct feeding aftermarket fuel rails.... cost wise I see it being way cheaper than ditching my current zl1 plus aux for a fore triple and I honestly cant think of a reason why it wouldn't work...

Anyone?

blake-b · 06-25-2020, 03:57 PM

Quote:

Originally Posted by Rem0v3r

I've been kicking around the idea of dual aux pumps..
Keeping it returnless, zl1 pump upto 1kpa my aux pump kicking in till wherever the limit is... then a 3rd pump on a seperate line , check valves, direct feeding aftermarket fuel rails.... cost wise I see it being way cheaper than ditching my current zl1 plus aux for a fore triple and I honestly cant think of a reason why it wouldn't work...

Anyone?

I did exactly this on my ZR1. I realize it isn't apples to apples and the OEM ZR1 pump is a bad mofo.

I added a second Bosch 044. One comes on at 8psi and the other 12psi. I should be in the ballpark of 1050+whp on a fully built 376 with a 2650 blower (2.4 upper; 14% lower).

No fueling issues with that setup.

Here is a post I made on it that might help you
https://www.corvetteforum.com/forums...post1600777660

Rem0v3r · 06-25-2020, 07:27 PM

Quote:

Originally Posted by blake-b

I did exactly this on my ZR1. I realize it isn't apples to apples and the OEM ZR1 pump is a bad mofo.

I added a second Bosch 044. One comes on at 8psi and the other 12psi. I should be in the ballpark of 1050+whp on a fully built 376 with a 2650 blower (2.4 upper; 14% lower).

No fueling issues with that setup.

Here is a post I made on it that might help you
https://www.corvetteforum.com/forums...post1600777660

That's pretty sick bro.. I like where you placed the fuel pumps.. mines a vert so I have mine bolted to a support stiffening rail.. 8an bulkhead fitting in the tank.. I'll probably add another 8an bulkhead to guarantee good delivery.. my zl1 pump starts to lose pressure right at boost cos I'm running e85.. my first aux pump kicks on at 107 kpa .. spikes fuel pressure to 85 then it settles around 72 at 10 ish lbs.. once I find the limit I'll know what to do.. Hobbs switch controlled.

blake-b · 06-25-2020, 07:42 PM

Quote:

Originally Posted by Rem0v3r

That's pretty sick bro.. I like where you placed the fuel pumps.. mines a vert so I have mine bolted to a support stiffening rail.. 8an bulkhead fitting in the tank.. I'll probably add another 8an bulkhead to guarantee good delivery.. my zl1 pump starts to lose pressure right at boost cos I'm running e85.. my first aux pump kicks on at 107 kpa .. spikes fuel pressure to 85 then it settles around 72 at 10 ish lbs.. once I find the limit I'll know what to do.. Hobbs switch controlled.

I run E85 also. Mine were Hobbs switched but I noticed a very short duration (as in you could only see it in logs) where the injector delta pressure was overcome by boost and the injector delta pressure would go into the upper 30s (vertical kpa line to 255kpa and it flatlined there) but would recover. I switched to dual MAP controllers to see if I could overcome it but it didn't. The sudden onset of boost is just too much for the injectors but they catch up. The MAP controllers were a bit faster but there is a still a lag. The next thing I am going to play with is fuel pump minimum duty cycle once I replace the driveshaft because I exploded the front guibo and am waiting on a carbon fiber replacement that eliminates guibos.

Also, I consulted some tuners about the lag and was told it is somewhat normal and probably controlled by a table in HPT we don't have access to. I was also told it is of such short duration it isn't an issue but I am going to play with minimum pump duty cycle out of curiosity.

Rem0v3r · 06-25-2020, 07:53 PM

Quote:

Originally Posted by blake-b

I run E85 also. Mine were Hobbs switched but I noticed a very short duration (as in you could only see it in logs) where the injector delta pressure was overcome by boost and the injector delta pressure would go into the upper 30s (vertical kpa line to 255kpa and it flatlined there) but would recover. I switched to dual MAP controllers to see if I could overcome it but it didn't. The sudden onset of boost is just too much for the injectors but they catch up. The MAP controllers were a bit faster but there is a still a lag. The next thing I am going to play with is fuel pump minimum duty cycle once I replace the driveshaft because I exploded the front guibo and am waiting on a carbon fiber replacement that eliminates guibos.

Also, I consulted some tuners about the lag and was told it is somewhat normal and probably controlled by a table in HPT we don't have access to. I was also told it is of such short duration it isn't an issue but I am going to play with minimum pump duty cycle out of curiosity.

Hmm.. interesting.. so your saying that you get a dip in fuel pressure before the pumps kick on or your pumps are kicking on and super spiking the fuel pressure..

I haven't seen anything like that happen in my logs.. I'm curious to see if your duel pumps are freaking out your fscm because they're hitting it quickly with a lot of force before it has time to react.

I'm measuring delta pressure in kpa not psi.. seen it go as high as 550 but never below 400

blake-b · 06-25-2020, 08:15 PM

I get a dip in both injector delta pressure and fuel pressure. The injector delta pressure is what the injectors see. My understanding is the fpcm doesn't react as quick as the boost comes on and lags just a bit before it jacks up the fuel pressure to overcome the boost. That being said, my MAP readings in the log below were quirkly. As in the MAP was spiking up and down during WOT but the car was pulling strong. I have replaced the MAP sensor during this downtime and won't know until I get it running again if that was the issue. I hope it is because otherwise, I have to chase down a wiring issue (yay).

Here is a screenshot. You can see pressures dropping when I go WOT. This is the run where the guibo broke. I noticed the fuel pressure and inj delta pressure being funny and I don't know what caused that behavior at that point. I know both pumps still work because the MAP controller has a test button and I tested both.

The bottom log picture is typical of the drop when going WOT. The DS broke right after the WOT throttle run in the 2nd pic. Well, probably during but didn't manifest itself until I stopped for a stop sign and the pulled away from it.

Rem0v3r · 06-25-2020, 08:39 PM

Ok.. so your injector delta pressure is dropping because your fuel pressure is dropping momentarily... I'd suggest logging your electrical current readings.. I'm going to hazard a guess to say that the 2 pumps kicking on at the same time is causing a large drain on your electrical system and messing with (something..ecu fscm..fuel pump etc).. fuelnpumps draw a lot of amps to run..

Try just 1 pump at a time and see if it goes away. Just my 2 cents.

06-24-2020, 11:00 PM	#21
John_C LSx FTW!!! Drives: 2010 Camaro 2SS RS Join Date: Jan 2017 Location: TN Posts: 767	I have the same issue. Car makes 760 rwhp with 13 to 14 psi at 6,800 rpm's and fuel pressure drops. ID 1300X injectors DSX Auxilary pump. DSX Flex sensor ZL1 in tank pump __________________ 2010 2SS RS A6 781rwhp on E85 Stage 2 ProCharger D1X Circle D 3400 Triple Disc Kooks Jet Hot Headers Kooks Full 3in exhaust Trick Flow GenX 255's Polished PAC .660's & Ti-retainers TSP VVT 3.2 cam kit w/DoD Delete Smith Bro's Trunnion kit AEM X-Series OBDII Widebands FIC ID1300x Injectors GM ZL1 High Output Fuel Pump DSX Tuning Flex Sensor DSX Auxiliary Fuel System Tim King Stage 4 Max Effort CTSV 6L90 DSS 1 piece aluminum driveshaft JRE 6L80E / 6L90E Dipstick NGK Iridium IX spark plugs #7 heat range Mighty Mouse Camaro 5 Wild w/-12an and Billet Black HP Tuners VCM Suite

06-25-2020, 08:15 PM	#27
blake-b Drives: 2009 ZR1 Join Date: May 2010 Location: KCMO Posts: 3,205	I get a dip in both injector delta pressure and fuel pressure. The injector delta pressure is what the injectors see. My understanding is the fpcm doesn't react as quick as the boost comes on and lags just a bit before it jacks up the fuel pressure to overcome the boost. That being said, my MAP readings in the log below were quirkly. As in the MAP was spiking up and down during WOT but the car was pulling strong. I have replaced the MAP sensor during this downtime and won't know until I get it running again if that was the issue. I hope it is because otherwise, I have to chase down a wiring issue (yay). Here is a screenshot. You can see pressures dropping when I go WOT. This is the run where the guibo broke. I noticed the fuel pressure and inj delta pressure being funny and I don't know what caused that behavior at that point. I know both pumps still work because the MAP controller has a test button and I tested both. The bottom log picture is typical of the drop when going WOT. The DS broke right after the WOT throttle run in the 2nd pic. Well, probably during but didn't manifest itself until I stopped for a stop sign and the pulled away from it. Attached Images Last edited by blake-b; 06-25-2020 at 08:24 PM. Reason: Messed up sequence of events in log

06-03-2020, 12:01 PM	#16
dookie454 Drives: 2010 Camaro 2SS LS3 Join Date: May 2012 Location: Michigan Posts: 143	Aux Pumps are puller pumps (pulling through lines from the tank), or inline with in tank pumps, both don't work well at higher flow, not because the pumps cant keep up, but because the suction side is the restriction. Whats worse is they can start to cavitate without you knowing, even if pressure is ok. In the case of the Aux pump pulling fuel from the tank, that suction side hose is the restriction. In the case of inline aux pump, the in tank pump is the restriction..once it starts dropping pressure, you start to starve the aux pump. In tank pumps are pusher pumps, which is what you want, just larger or more of them. They minimize, or remove the suction restriction, since they are submersed, which is key. However with the larger or addition of in-tank pumps, you need to have a way to modulate (slow down) all that pump with dead head system, then run wide open for max HP, this is easier to do with a return style setup. I know this since I've had many a problem with this, one was a simple remote mount large pump, pulling fuel from a hose going to the tank from the top, to the bottom of the tank. It worked well most of the time but it would start to cavitate during the highest of flow demand.. creating all kinds of weird side effects.

06-03-2020, 03:22 PM	#17
Rem0v3r Drives: 2013 ss2 vert l99 Join Date: Apr 2017 Location: South florida Posts: 150	I have elesthrees old aux setup and run 75% ethanol full time.1000cc.. I'm currently building my motor with forged goodness and a tsp turbo stage 2 cam.. I fully intend on finding the limits of this fuel system once my car is back together :-)

06-23-2020, 06:46 PM	#19
Rem0v3r Drives: 2013 ss2 vert l99 Join Date: Apr 2017 Location: South florida Posts: 150	Dont get hung up on fuel pressure too much with the aux pump.. your ecu calculates the pressure delta between the fuel and the air and delivers the correct amount of fuel.. you need a specifically high pressure delta to maintain a good spray patturn.. In short.. stock is 58psi.. if your aux spikes the pressure to 85 and it drops down to 74.. but your only pushing 15psi boost.... it really doesn't matter... If however you only got 40psi fuel pressure.. you got problems.

06-25-2020, 03:40 PM	#22
Rem0v3r Drives: 2013 ss2 vert l99 Join Date: Apr 2017 Location: South florida Posts: 150	I've been kicking around the idea of dual aux pumps.. Keeping it returnless, zl1 pump upto 1kpa my aux pump kicking in till wherever the limit is... then a 3rd pump on a seperate line , check valves, direct feeding aftermarket fuel rails.... cost wise I see it being way cheaper than ditching my current zl1 plus aux for a fore triple and I honestly cant think of a reason why it wouldn't work... Anyone?

06-25-2020, 08:39 PM	#28
Rem0v3r Drives: 2013 ss2 vert l99 Join Date: Apr 2017 Location: South florida Posts: 150	Ok.. so your injector delta pressure is dropping because your fuel pressure is dropping momentarily... I'd suggest logging your electrical current readings.. I'm going to hazard a guess to say that the 2 pumps kicking on at the same time is causing a large drain on your electrical system and messing with (something..ecu fscm..fuel pump etc).. fuelnpumps draw a lot of amps to run.. Try just 1 pump at a time and see if it goes away. Just my 2 cents.