fuel regulator question with fel pro

[Otto J]

do you still run a boost line to your fuel regulator when running the speed pro ecm? do i really need to run fuel pressures as high a 70-80 psi anymore?i believe the ecm should be able to supply the fuel
thanks OJP

 

[TurboTR]

Yes you should still run the hose to the regulator. If you really need a delta P of 80 psi to get the fuel your engine requires then you probably also need larger injectors.

TurboTR

 

[Otto J]

i think that my return line might be to small i have a dbl pumper and under boost it wants to be that high no matter what i do, i am running 83 # injectors but a stock turbo,my lt70 should be here next week
thanks

 

[tazgn]

Yes, You would need to run the pressure line to the regulator. That line is there to maintain the differential pressure required across the fuel injector. In other words if you had 25 psi boost and fuel pressure of 40 psi, that's the same as only having 15 psi of fuel pressure with the engine at idle (ignoring vacuum). The injectors are designed to work at that low of diff pressure across them. But I know what you are talking about with the double pumper and the return line and uncontrolled pressure when the second pump kicks on. I had the exact same problem, and ran for over a year with the second pump disabled because of it. I just put new fuel supply (-10) and return (-8) lines on the car and the CAS sheetmetal and his dual port regulator. No problems now. I really think it was the old regulator not the return line, but I can't be sure.

Derrick

P.S. I need your e-mail address to send the 83# programs to you.

 

[TurboTR]

I've been running a double pumper for several years too, and the solution for most people is to just stage the 2nd pump so it only comes on at higher loads.

TurboTR

 

[Otto J]

what i was going try was trigering it with the third gear switch in the tranny, it is probably not need until 3rd gear anyway,
me email address is KILLERV6BUICK@aol.com
thanks Otto

 

[vtec4gs]

not sure if this helps, but on some of the hondas that I tune, the turbo kits came with boost sensitive regulators jsut to accomodate more fuel on boost with stock injectors, the minute I installed aftermarket management and larger injectors I changed regulator to non boost senstive, i.e Paxton or Aeromotive so it does not increase pressure on boost, so more fuel is accomodated via increased PW.


Greg

 

[Craig Smith]

With the FAST system, you have to have a boost-referenced FP regulator. If you don't have one, you essentially are changing the flow rate of the injectors as manifold pressure varies. The ECU doesn't know this and calculates an injector pulsewidth on the assumption that the injectors are flowing XX lb/hr of fuel. IMHO, if XX changes to YY under boost, you engine could be KIA and then you are SOL.

 

[Otto J]

thanks for the feedback craig. it is an awesome system, i am just hving problems returning the fuel when my second pump kicks in, i will be adding a larger return line to fix that problem
Otto

 

[TurboTR]

Well rather than go to that trouble, you can probably just adjust your Hobbes to come on at about 20 psi boost or so, and likely solve the whole problem.

turboTR

 

[Otto J]

do you know where i can get an adjustable hobbs switch.mine i dont believe is adjustable
thanks Otto

 

[TurboTR]

Look for a rubber plug down in the snout of the switch. If there, lift it out and see if there's a hex head adjuster down inside. A Mityvac "Turbo Test" handheld pump makes a nice, adjustable pressure source to set it. In the GN app a single 307/340 seems able to safely support about 123-124 mph or so through the stock lines and filter, so it seems reasonable to set the 2nd one to come on at the boost level that would give you about 116-118 mph or so. That way you're only asking the single pump to cover you to about 118 mph, which it will easily do. And by that time the fuel volume into the engine is high enough that the return line has plenty of room to spare for the 2nd pump to come on

IME the double pumper setup with the stock lines and fresh filter will go at least in the mid 130's mph with no observed delivery issues. Probably not an ideal feed and filter setup at that level, but it will do it with no volume falloff at the end. And that's the whole point really, supply adequate fuel volume to the engine.

Otherwise, I think NAPA may even sell Hobbes switches. There's also a website for Hobbes. Or ask Jack to get you one

JMO. YMMV.

TurboTR

 

[Otto J]

thanks guys for the help will check the switch