oscs

iTrader: (19)

Made some hits this weekend and even with two 4303 pumps running at the same time I'm not getting 1:1 increase in fuel pressure with boost. The car saw 15-20lbs and hovered around 60psi FP. The car still has the smallish Aeromotive regulator on it. Both pumps have a -10 feed that feeds into a -10 fuel feed line. So -10 to regulator -8 return. I know this isn't optimal but has worked for others.

My question is how on earth with all that Fuel does pressure not rise when i ask it to? Base FP was set to 45 and will maintain so on 1 pump. With both pumps fired up it would hover at 60psi. last Friday at the track we couldn't get the holley to send a signal to the second pump so we just ran both on and adjusted FP to 60psi base.

Also what about setting base pressure back to 45, having one run all the time and then having the second one staged like i originally planed. Anyone think that will allow the smaller regulator to rise like it should?

Thoughts

caMnaro

iTrader: (24)

I think the return port on the regulator is the restriction when both pumps are running at idle.It is probably to small of a port to return all that fuel back, So you have the spring/ball probably turned almost all the way out. Once the engine starts consuming all the fuel and the regulator actually tries to build pressure, the spring doesn't have enough tension to keep it 1:1. I think you are on the right path on running one pump and one boost referenced. Try to unplug one pump and see if the base pressure drops without adjusting the regulator, that should show if it cant keep up with both pumps on.

3 window

iTrader: (1)

Do those pumps have a pressure they are set at from the factory and then you can adjust them as needed, higher or lower? Maybe they're factory set at 60 psi, but you can bump them up. I don't know anything about the manga fuel pumps, but that's the first thing that came to mind.

Mike@Diablosport

iTrader: (2)

I've seen opened up regulators that illustrated the actual size of the return, they are often much smaller than the AN size they are 'advertised' to have externally, I wouldn't be surprised if that's the issue.

JoeNova

2800 HP worth of E85? Why? Guys run 7s on E85 with a single 4303.

How many volts are your pumps running at? Typically, pressure spikes when you have too much fuel and not enough return, not the other way around. Chances are, you've overwhelmed the regulator and it can no longer close the return orifice enough to increase pressure. Your fuel line size is fine, regulators typically only have an opening in the return that flows 60-75% what their AN fittings do.

transam69230

iTrader: (49)

They need check valves for sure!

My two small pumps run all the time, and my 4303 would come on with 4lbs of boost. After I got done making a pass my fuel pressure would drop to 20psi. It would actually do it sometimes mid pull and go super lean.

My system was Y'ed together, I assume you have the pumps Y'ed as well? If you are using a Y , its very likely that one of those pumps is back feeding into the other.

43base at 26lbs I am seeing 70psi of fuel pressure.

stevieturbo

So when you test the system by applying pressure to the reg, does pressure rise as expected ?


And I've yet to see any regulator I've ever tested perfectly match 1:1, they all fall a little short of that especially at higher pressures.

At the end of the day it isnt a worry as long as it always does the same thing.

20psiofevil

I'm running twin 255's on a stock style regulator with 43psi base pressure. -8 feed and return on pump gas around 600rwhp. Have the 2nd pump activated at 6-7psi via a nason sq2 boost switch. 16psi and it hits 59psi on the rail like a champ. I will say this though, the internal pump built in check valve will open up at 73psi according to my bench testing. I just use a basket ball pump with a series of vac lines/hoses to bench test a lot of stuff.

oscs

iTrader: (19)

Correct. I wasn't sure what everyone was missing with the whole return theory. The dual 4303 will not flow anywhere near 2800hp on corn. They are on the ragged edge of 1000whp on E85. My question is this. Do you think it would behave the same way if I staged the second pump?

oscs

iTrader: (19)

The second pump has a check valve

oscs

iTrader: (19)

I haven't tried that Stevie. Most all runs it hovers around 60psi but on one hit (boost spike to 18psi almost instantly) it rose to 70

oscs

iTrader: (19)

What is a good regulator to hold back this much fuel?

Blown06

iTrader: (32)

there is a massive thread on yellowbullet that I created regarding this exact issue. I'll post a link up and that will end this thread and your problems.

Blown06

iTrader: (32)

Alright, here is a link to a monster thread on yb, basically discussing all of the growing pains I had in getting the truck to work. Toward the end is where we really start getting after the 1:1 fuel pressure/boost issue.

http://www.yellowbullet.com/forum/sh...577454&page=14

This is the main thread regarding only the fuel pressure issue. You can see the 9 million things I tried as requested by other members and at the end see that the fix was the big aeromotive regulator.

http://www.yellowbullet.com/forum/sh...ight=regulator

oscs

iTrader: (19)

Your my hero Travis!! BUT when I text your *** you said you did not have rising issues..

Blown06

iTrader: (32)

I must have mis-understood what you where asking. Feel free to call me anytime if you have questions.

RonSSNova

iTrader: (3)

I tested my system by simulating boost to the FPR all the way to 80 psi fuel pressure. Logging both boost (map kpa) and fuel pressure with HPTuners and also measuring boost and fuel pressure with mech gauges.
It was a good test to ensure calibration of the sensors. Especially the MAP as I built it myself.

It stayed 1:1 perfectly.

I have the Holley 1800 pump and matching regulator.

Of course the engine wasn't consuming fuel.....

In real life it stays 1:1 through 15 psi boost. Above that it looses 2 psi of fuel pressure when I'm at 18 psi boost.
I'm reading this as being out of pump as I'm on 60 base pressure E85 pushing ID1000's.
-8 supply and return BTW.

Good to know the Aremotive FPR is very high flow. Might be one in my future.

Ron

Forcefed86

iTrader: (4)

I spoke with maganfuel and they say 1000FWHP is about the limit on a standard 13.5v E85 setup at 70 psi total pressure. Little extra voltage goes a long way I’m told. If you run retardo huge injectors and supply lines you can carry it a little further.

Unless you need more base pressure to carry small injectors the lower the base FP the easier it will be on the pump. 43psi is the standard for a good spray pattern, I see no reason to run higher if you don’t have to.

I run the cheap 4305M Mallory FPR and a single 4303. FP logs show 1:1 almost exactly at 20lbs. My fuel does heat up on 30-40min drives, esp if I run the 12g tank low on hot days. But the added heat has never caused a problem. Pump gets too hot to comfortably touch though, so It’s not a good thing. I can’t imagine running run both pumps.

Your ECU can PWM control that pump easily. That is the best option hands down. PWM one pump and have the other kick on when you need it. It quiets the pump a ton and won’t heat up the fuel. Zbrown’s Holley is PWM controlling his 4303. Shoot him a PM. I’m sure it wouldn’t overrun your current FPR this way either.

http://www.jegs.com/InstallationInst.../650-4305M.pdf

stevieturbo

How hot was your fuel getting ?

And if PWM'ing the pump...may as well just PWM both. Keeps it simple and flow always remains smooth.

coltboostin

Why would that cause it not to rise at the correct rate? A small return orifice would just show as an issue if pressure could not be LOWERED to your target.



To the OP- 2 things

1) Test it with the car not running. Build a little rig so you can pressurize it with an air hose. This will tell you if its a regulator issue, or a SIGNAL issue.

2) Most regulators I have seen do not give a true 1 to 1 rise, even the high dollar ones. If you are not ruining out of fuel, I would not worry about it as long as it rises in a consistent fashion.

3) If you test it and it shows true 1 to 1, make sure you a have a TRUE and dedicated signal line off the source, not off a vacuum block or "T" line. I cant tell you hoe many times I have changed this out of customer cars with FP issues and cured the problem.