NightmareTA

iTrader: (20)

Old fuel system was half assed at best, and consisted of twin in tank walbro's into a -8 feed line connected to stock fuel rails with 60 lbs injectors. Had a -6 line "T" off the main feed line and go back to the tank through the stock in-tank 4th gen regulator. This setup "worked" but the pressure was never very consistent and would fluctuate between 65 psi when cold and lately has even been dropping as low as 50 PSI when warm after driving for a bit.

Finally doing it correctly and ordered the following...

-Holley LS fuel rails
-Aeromotive return style regulator capable of supporting an A1000 pump
-Lots of shiny fittings and braided line

My idea is to run a true return style system with a dedicated -6 return line going through the aeromotive regulator and then back to the tank. I plan on using the factory return port on the sending unit in the tank and just removing the stock regulator from it so fuel will free flow through it. Keeping my existing -8 feed line setup as well and just blocking off the "T" part.

Now the only area I'm concerned about is what to do for pumps. Should I keep the twin walbros? Switch to a 340 lph pump? The car used to be pump gas only but I have just added an alky control kit so it will not need quite the pump power anymore. Just trying to simplify my fuel system as much as possible, so any input, tips, past experience, etc please add in!

Oh, and one funny thing I noticed when the pressure had dropped to 50 PSI the other day...

Just for kicks, I unplugged one of the pump relays and observed the pressure drop to 40 PSI. Plugged it back in and then unplugged the other relay and it dropped to 35 PSI....It's odd that it would fluctuate like that between pumps. I'm curious if maybe they are getting weak, or at least one is? Also, I'd think that even just running on one pump at idle, the pressure should of stayed at 58 PSI regardless and not dropped at all?? I'm going to test volts at the relays and see exactly whats going on. The pumps are only 3 years old but I guess they could be shitting the bed already...?

Anyways, thanks ahead of time for any info.

JoeNova

Twin walbros flow more than a single 340, and more than enough for 600 HP. A single walbro 255 when set up properly can support 600 HP on its own.

willizm

iTrader: (10)

Honestly twin 255 pumps will take you to your goals and then some. On e85 I was making 750+whp before switching out my twin 255's and 95lb injectors to twin 340's and FIC2000's. If your staying on 93oct I'd think you got more than enough pump for your goals. Put your money toward your fuel reg/return. You'll max out your 60lb injectors well before your dual 255's.

NightmareTA

iTrader: (20)

Yea the twin walbros have been great for fuel delivery so far. I may have worded it weird, but I was asking about going to a single 340 over the twin 255's since I'll have methanol injection now to help it under boost. Also it's really bugging me that the pumps in there currently seemed so weak when running individually. I haven't dug into it yet, but I'm really hoping to either find that they have low voltage or a rubber fuel line inside the tank split. Going to suck if they are just plain going bad.

Oh, and my end goal for this season is 15 PSI + meth and shooting for mid 6xx rwhp. Nothing crazy but really need to get this fuel system running top notch and issue free.

willizm

iTrader: (10)

That is kinda weird. I ran a hobbs switch and so only one pump would run until the car gets into boost. Even with the one pump and the reg it held a-ok at 50psi. Do you run a hotwire off of the alternator? Wonder if it's a power issue and if you swapped out pumps you could very well still have the issue.

NightmareTA

iTrader: (20)

That hotwire setup is interesting...

I run this exact setup in my car to power the twin pumps and a few other things.

http://www.jegs.com/i/Painless/764/3...FUFufgod2nAA-A

At the moment, the relay banks main power feeds go directly to my battery, and I have one relay per pump, so each has it's own individual power. My battery is in my trunk and I'm not sure how much voltage drop it's experiencing going from the alternator to the battery. I bought a ready to go trunk mount wiring kit off summit so I figured it was adequate enough to transfer the alternators charge to the battery in the back. I should probably test it to check out whats going on.

denmah

iTrader: (2)

i have done 600+ with just a single bosch 044 fuel pump

or twin 255s in the tank, no fancy stuff just wired all the time

or a single 400 in the tank...

no hobb switches or other things.

Boosted Firehawk

iTrader: (11)

NO hobbs?

Just constantly running 2 pumps all the time?
Doesn't that make it run like **** at idle and over fuel?

JoeNova

As long as your pressure is constant, your injectors aren't spraying any extra fuel. The problem most people have with running twin pumps all of the time is keeping the fuel pressure constant.

NightmareTA

iTrader: (20)

First off...as an update to my issue with the fuel pressure, I think I found it. Was screwing around in the garage after work and had the car running for a bit. Shut it down and then turned the key to accessory a few minutes after to roll the window up. Thats when I noticed my fuel pressure gauge prime with the pumps to 60ish PSI, and then immediately fall to around 10-15 PSI the second the pumps stopped. The system is no longer holding pressure, so I either blew out the stock regulator, blew a rubber fuel hose inside the tank, or my pumps are just getting weak. I'm really hoping it's the POS stock regulator, but I'll know in a few days when I tear it apart.

I like the twin walbros I currently have honestly...my main concern was if I'm having another issue since the fuel pressure is so low with just one pump running at a time. If I find the issue, I'll probably keep the twins in there.

Runs great "when" the fuel pressure is consistent. The problem is the stock 4th gen in-tank regulator just isn't up to the task of keeping the fuel pressure consistent between the twin pumps. Before this recent issue arose, I would cruise down the road at an exact 14.5-15.0 AFR, and idle varied between 12.7-14.3 or so. Depended on what the fuel pressure was at the time...idle is where it had the most difficulty staying at a consistent pressure, but thats why I'm redoing the whole thing now. Need a real fuel system.

I don't plan on running a hobbs switch either. Plenty of guys run the twin pumps all the time and there is no downside IMO. If a hobbs switch fails, you think everything's ok until the second you hit boost and you start leaning out. Just too complicated for me...I like simplicity. I have an electric fuel press gauge in the car and I have trained myself to keep a close eye on it. If anything ever looks fishy, I stay out of the gas.

Yea, I like running them both all the time. The consistency is why I'm going to a dedicated return style fuel system now. Should work MUCH better with the right amount of flow now.

skinnies

iTrader: (33)

Stock rails with a regulator before them works just fine for the power you are looking for, we've made 900+ on stock rails and e85. I'd keep it simple, twin 255's, stock lines under the car, put a mallory 4305M regulator just before the rails.

KnightmareLS1

iTrader: (12)

Were you running both theses pumps all the time or using a Hobbs switch?

123quattro

That's just a matter of preference. It wouldn't matter which way you did it.