Badmonkey

iTrader: (9)

Ok, here is my situation. My fuel pressure drops steadily from 53 psi all the way down to 22 psi, if I am at 3/4 to 7/8 throttle with about 5-8 inches of vaccuum. When I go to WOT, the aux fuel pump kicks in and it runs fine. Is there an adjustment for when the aux pump kicks in according to the TPS or is it just based on vaccuum/boost? Shouldn't my stock fuel pump supply enough fuel while not boosting. Do I need to buy an aftermarket fuel pump?

2nd question: If I go with larger injectors and the Walbro pump, do I have to get the return fuel system? I am sure that this all would take care of my pressure problem, however, I don't want to go with the return fuel system, unless I absolutely have to. Thanks for all the expert help.

Badmonkey

iTrader: (9)

C'mon, somebody has got to know what is going on here, please!!!

SR20DEN

iTrader: (2)

You don't have to go with a return fuel system. If you simply and correctly upgraded the returnless fuel system your problems would be solved. A returnless system is better for keeping fuel temperatures down. The Walbro alone should be sufficient.

overZealous1

iTrader: (27)

i am having similar issues with mine. it is not a fuel delivery problem on mine though. and my pressure only drops maybe 5 pounds not down to 22!!! i am surprised yours would make any power at all or run at 22psi. most pressure regulators adjust fuel pressure lightly from a vacuum source (less pressure at high vacuum and more pressure at little vacuum or boost) i am not sure if the Z uses this type of regulator yet as i have not checked but i do have alot of experience building fuel systems for v-8's and those are prodominately used.
is it a problem you have had since your procharger install or progressed after?
when i mash it i have watched my fuel pressure jump to 80+ psi with the aeromotive fmu. that fmu is only using boost to gauge it's turn on point and believe it does not use any reference for vacuum (someone correct me if i am wrong) did you have the car tuned in or just go with the original settings that were in the instructions?

Badmonkey

iTrader: (9)

I don't think the problem was there prior to my S/C installation. The car ran as advertised. I actually feel the car bog down now when the PSI drops to 22-24. I had the car dyno tuned when the installation was done.

SR20DEN, Will the Walbro be fine to run my 440 injectors with a TS reflash? My goal is to get rid of the FMU all together.

Sharif@Forged

iTrader: (92)

Badmoney, are you running the Aeromoetive FMU and with the booster pump voltage sliders? If so...you should be able to increase fuel pressure voltage at the preset points. Sounds like it just needs some tuning...unless I am missing something.

One thing I will say is the FMU included with the ProCharger kit is a horrible setup...and can be dangerous...I cant stress that enough. 100+psi of fuel pressure running through stock injectors as anything buy ideal, and the voltage adjustment points on the Aeromotive FMU included with the ProCharger kit are far too crude...you have very limited resolution in terms of dialing in fuel.

I know you don't want a return fuel system, but its the best and safest way to go. Return fuel system, and boost dependant rising rate FPR, and Walbro 255. My guess is that you wont even have to add any additional fuel at all with this setup....if running 440cc injectors. Hell, even stock injectors might work OK with the return setup....without any extra fuel. Base fuel pressure can be set to 52psi, and then 1:1 increase as boost rises. So around 60psi of pressure at max boost..assuming you are running 8psi. And your fuel pressure will always be a steady 52psi at idle and cruise....or whatever you choose to set it at.

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