Podium

Im building a fuel system for my z06. I like the idea of using a factory style pump along with a 2nd external. I read a few guys who ran their 2nd pump constant vs using a hobbs switch. Ive never ran a hobbs switch but I like the thought of a external constantly on vs the hobbs switch. Constant power would also be more clean of an install.

Just looking to the pros and cons before I start buying everything.

Turpid porpoise

You dont want to run the external pump when you dont need it, all that will do is unnecessarily heat your fuel.

inspector12

Turpid Porpoise is correct. All I have seen do that have had the external pumps burn up over time depending on the pump, but most wouldn't make it 6 months. Staged fuel systems work great and don't add any unwanted heat. The fuel regulator should keep the fuel pressure from swinging much if at all when they come on. GL!

junk c5

I have an external Magnafuel 4303 wired to run continuously. Personally I would rather not rely on another component to turn on the fuel pump. To me that's just one more component that could malfunction and not turn my pump on when I need it. I run E85 so I'm not worried about my fuel getting overly warm. I ran a Bosch fuel pump externally for about four seasons and I am on my second season with the magna fuel pump. My car is not a daily driver, more like a weekend warrior.

Podium

Thats how I feel. My car is a daily driver in the summer when its nice out. I will also be on e85. Hoping to run flex fuel on the c5 as well.

inspector12

Yeah cause your not driving your car that much you've had one hold up that long. I know of three people that have gone through two or more of the 4303's. I'm guessing its because of the location doesn't get enough air flow to keep them cool. But hey have at it not trying to tell anyone how to build there cars, just offering what I know has happened to friends and customers cars I've worked on. I am located in Houston,Texas so that could have an effect on how long they've lasted as well. I don't think a Hobbs switch is unreliable as it could fail just as well as the pump IMO. GL!

neverstop

I don't see why one wouldn't run the hobbs. they are about as reliable as it gets.

FourG63 97GST

sorta on topic, any downside to running the external pump on a window switch?
I've never seen that done, ideally on supercharged cars where boost is somewhat rpm related anyway.

inspector12

Not that I can see. I think you could use a WOT switch or window switch how ever you want, what ever you wanted to trigger it with as long as you can verify your not going lean or dropping FP during a pull etc...

junk c5

I've been doing some reading about adding a Hobbs switch to get away from the constant race car sound and what I've seen sounds concerning. From what it sounds like, with just one pump going and the fuel pressure at 43 lbs guys have had problems with the fuel transfer system at that low of fuel pressure. Does anyone have any input on that topic ?

winters97gt

Mine lasted 3 weeks on my C6 from a forum vendor. A1000. Put it on a Hobbs.

Rkreigh

what ecm are you using for e85?

I'm going to try a Haltech S2000 with flex fuel sensor and the computer will control the external pump and has penty of failsafes if either of the pump fails.

I've also heard of backfitting a factory e85 computer and repining and reprogramming to work with the c5 stuff.

broke right now, but $ are coming

trayack

The initial setup on my car was a internal LPE 255 and an external Bosch 044 that ran all the time. That setup literally lasted one day on Drag Week 2014. V2 on the car was an internal 255/340 combo with the 255 as the primary and the 340 coming on via Hobbs at 2psi. That combo ran great with no real issues. I'd do the Drag Week drives on one tank with no fuel stops and still have 1/8th tank left each day. I will say that that after the whole week the primary pump was none too happy with that low fuel level but it still toughed it out.

This winter I pulled both pumps and replaced them with two new Aeromotive 340's. Not expecting any fueling issues if the future. Also, we've swapped cam's and picked up a sizable amount of power. I'd expect 8.9X on 93 pump with the new setup.

- Travis

inspector12

Well you have to change the regulator in the passenger side tank to allow it to transfer at lower pressures. But if you've done that I don't know of a lot of issues with anyone locally. The Fuel system in general on vette's isn't user friendly, but it does work when all is together correctly. I run my current C6 at 40lbs base pressure. Not exactly the same but the function pretty much is. On other C5's setup's I never ran less than 45lbs but never had issues with the transfer. GL don't know if my info offers any help or answers for you, but it is all I have for you lol! GL!

junk c5

Thx. I didn't even know there is a regulator in the passenger side tank. I might have to look into this.

inspector12

Yeah I think the factory one won't transfer under 54psi I'm guessing right now as I can't remember exactly but I'm about 95% that's correct. Fore Innovations makes one and so does Lingenfelter. Fore sends one with there fuel pump modules, and I have an extra one if you need one.

http://www.lingenfelter.com/product/...l#.WPVpbJh1rcs

Patches

Lingenfelter site says this is for the 2003-1/2 and up with the C6 fuel setup. Any application to the C5 platform prior to that?

"The Lingenfelter fuel pressure regulator block off is precision CNC machined from aluminum and then anodized red for added durability.

Designed for Corvette applications:
2005-2007 C6 Corvette LS2 engine
2006-2007 C6 Z06 Corvette LS7 engine
2003 1/2-2004 C5 Corvette LS1 or LS6

Note: General Motors switched the C5 Corvette fuel systems over to the C6 Corvette fuel system design halfway through the 2003 model year. Corvettes with the last 6 digits of the VIN being 114930 or higher were produced November 25, 2002 and later and have the new C6 style fuel system.

This regulator block off should be used in conjunction with the Lingenfelter driver side fuel tank block off fitting."

junk c5

I've got an early C5. 1999 model year.

DOUG @ ECS

If you are worried about a hobbs switch failing then set it up like an airplane and use two. Check them once a year just like an aircraft's annual inspection.

Small price to make your car fly...

inspector12

Well sorry my info doesn't help you. Maybe not able to lower FP on your particular year.