I have an intercooled procharger p1sc kit and i can't get more than 41 psi in the fuel rail. The fuel pressure regulator won't produce any more reatriction on the return line when it is under boost. I was wondering if anyone else ran into this problem??? I am not using the supplied FMU, I have 42# injectors and a 90mm L maf. Any suggestions will be helpful.
Thanks
-Frankie

 

It sounds like your fuel pressure regulator is doing what it is designed to do. That FMU is designed to increase your fuel pressure at boost. There are adjustable fuel pressure regulators that can achieve higher pressures, but you don't indicate whether you're using one of these. However, an adjustable fuel pressure regulator will provide the same amount of pressure and has no way to recognize boost, only vacuum for lower load operation. You should not need any more fuel pressure with the right injector sizing, a properly calibrated MAF transfer function in the PCM and a fuel pump capable of providing fuel to the injectors.

 

41psi is a lot if your running 42# injectors, who is doing the tuning?

 

what fuel pump(s) are you running??


how much HP are you making??

 

Fuel pressure should be 39 psi with vac line off and plugged.

 

ok to answer all of your ?'s i have 42# injectors, the fuel pump that comes with the procharger kit. The people that are tuning my truck do a lot of pulling trucks, dirt track cars, drag cars, they are called Full Boar Enterprises, they are in Dodgeville WI if anyone knows them. I don't know how much HP yet bcause i don't have my belt on (i don't want to boost an untuned motor). I was told by the guy doing the tuning that he couldn't get enough fuel because there was a limit on the PCM that only allowed him to tune up to 66# or something like that, of air through the MAF, so he was running out of injector to work with. Also the fuel pressure only goes up until vac is gone once boost comes it doesn't rise, the guy doing tuning told me that Fuel Press. should rise 1 psi with every1 psi of boost added. He is researching and tryig to figure it out because he has never done a 5.4 but he said that the 4.6 works as prviously stated, the fuel press rises 1 psi with each 1 psi of boost. any suggestons welcome
Thanks
-Frankie

 

as far as i know he wasn't WOT on any of the pulls but i got a quick glance at his computer and i saw 387 at about 3000rpm and i have a 125 psi inline pump and the stock pump as well.
-Frankie

 

I don't think 387 hp @ 3k rpm is realistic.

 

Someone correct me if I'm wrong ,but doesnt the stock kit come with the in-line pump and an FMU?
The FMU is designed to increase the pressure of the (STOCK) injectors.
Now that you have 42# injectors and 90mm MAF you need to put a 255lph pump in your tank and get rid of the in-line pump and the FMU!
I believe your tuner will have no problem tuning it then.

I run 16 to 18 PSI and Iv never seen my fuel pressure go above 45 PSI!

Phil

 

it's not, unless he's pullied for around 40#...



is the truck running lean with the boost-a-pump??

I ran mine with the ATI boost-a-pump and fuel mods but it's not advisable

 

Get rid of the ATI Booster pump and put a 255LPH pump in the tank. If he still says he's running out of fuel at that point then pull the truck out of there, because he clearly doesn't know how to tune it then.

 

Ok so the 255 lph pump, will it make my fuel press. higher? how much does one cost?? are u using the FMU?? and does your fuel press. rise as the boost does??, because mine does not.

 

yeah i didn't get to look at the compter for more than a few seconds so i dunno if those #'s are right or not but i was pulling 6 psi of boost. i dunno we'll find out soon enough.

 

This is the cheepest place Iv seen to get the pump.
http://treperformance.com/i-788624-f...1997-2002.html
1 255lph pump,42# injectors,90mm MAF will support 450,480RWHP! With NO FMU.
The FMU is only for when you don't have the fuel mods.(then you need it) but you have the fuel mods. You just need to add the bigger pump and eliminate the FMU and in-line pump.

No,,my pressure dose not go up with boost. And I run two 255lph pumps and 60# injectors.
My pressure runs between 32 and 38 PSI. The highest Iv ever seen it was around 42psi.

Phil

 

it may have been torque... which would be about right