As far as I know 2003 was the return style fuel system.

 

yeh your right. I just did some surfing. My bad. i mistook 2 instances as '03's. '04 is when GM decided to screw everybody.

Sorry for the bad info. Ugh.

 

at least you can get an in-tank fuel pump for those w/o issues...

 

Found this info on Summit Racings site about the Vortech FMU...

"Increase fuel pressure according to boost.
These Vortech Standard Fuel Management Units are designed for use on multi-point fuel injected engines. They are secondary fuel regulators that install in series with a stock regulator on the return line to the fuel tank. The units increase fuel pressure in proportion to boost pressure (assuming that the pump being utilized has sufficient pressure and flow to deliver the fuel required). "

By using one of these we should be able to tune the truck so that it will run almost "stock" fuel ratio when not under boost for maximum MPG but, have all the fuel it needs during boost, right?

 

That is exactly what the ATI ProCharger FMU did as well...

 

Guys, FMU are considered a bandaid approach to add fuel mechanical while in boost mostly for motors with computer that can't be tuned. They increase fuel pressure per pound of boost so that the injector squirts more fuel for the same amount of opening time. They really make the fuel pump work HARD. Think about this, A 10:1 fmu is increasing fuel pressure 10 psi for every 1 psi of boost. So at 6 psi of boost, that 60 psi of fuel pressure . Add that to the 58 psi it's already at and your fuel pressure is now 118 psi . Think if your running 10 psi of boost . Do you really want to run that much fuel pressure, when you can easily get better results with tuning the computer to add fuel like its supposed to? I messed around with FMU's on a 2.8 TBI S-10 I turboed. It was a pain to tune, because I had to "bleed" boost pressure to the fmu to try to get the fuel pressure where it needed to be to get the fuel right for boost. Most tuners will not even mess with a FMU if the is a viable option for tuning like are trucks have with EFILive and HPTuners.

All you really need is a vac/boost vef fuel pressure reg that will raise fuel pressure 1:1 like what these truck came with from the factory until 04, so the injectors think they are still squirting in to 1 atmosphere. The return-less fuel system is a little harder to tune and won't go as far on injectors, as the return style, but it still works, just have to upgrade to 60's sooner .

 

Again, don't worry about an aftermarket FPR until you need to change fuel rails imo. Don't, by any means, use an FMU -- get the correct sized fuel pump imo.


This is exactly what the stock FPR does for you on a return style truck. No add-ons needed.

 

oh... I see... Now i understand...