Fuel Pressure ?????

NeedaSY

Go Ahead N Go
What should my round about fuel pressure be??
Stock injectors
Ultimate Chip
Walbro Fuel Pump

Its set now at 39psi Can I safly bump it up some or am i good?
 

dgoodhue

BuSTeD 4.3
Re: Fuel Pressure ?????

It's just a six said:
What is your air/fuel ratio?
Should look into getting a wideband O2 meter.

What he said, what does the scan tool say, any knock retard? Typically the stock injector ultimates run between 45-50psi of FP with the vacuum line off.
 
Re: Fuel Pressure ?????

Ok, call me stupid but....
It seems that there is a WIDE range of suggested FP settings.
I am more confused now after reading 20-30 posts than I was when I logged in.
Sunday is a tuning session for me and I'd like to have an experienced opinion so I have a starting point. Definately don't want to waste a day of tuning and find out later that I should have had a little more pressure.

I have 50# inj (flow matched at 43.8? see pic) with stock turbo, 3bar and boost up to about 18lbs.
JS originally told me 42lbs. with my bin but it ran so rich it wasn't even funny. I have two black spots on my garage door to prove it. I then turned it down to 35lbs and it seemed much better but lacking at higher rpm's. I know much of it will be in the tune, but where do I start? Should I set it (with vac off) at the flow rate of 43.8 and tune from there?

Thanks in advance guys, 'm hoping Sunday will be a success.
 

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NeedaSY

Go Ahead N Go
Re: Fuel Pressure ?????

Well gauges were my next in line parts for my truck intell my cell phone bill hit $200. But once i get that on there i guess i can answer my own question.

By the way what vaccum line we talkin here cause i already dont have EGR solenoid and a Block off plate.
 

TYTILIDIE

METH HEAD
Re: Fuel Pressure ?????

What Ive noticed is that if I have the FP set low it will lack at high RPM and will idle rough. I think that with it turned up higher it will atomize better and you give you much better running conditions. When I first got my truck running with the current mods, I had it set at 40. I had no top end and was running very rich at idle and lean up top. I bumped it up to 50 and noticed a huge improvement. I then turned up boost and ended up being at 60psi with 02's at 910 and idle loooked great. Ild say go up before down.
 

cvcsmkr

Donating Member
Re: Fuel Pressure ?????

ill just give you my experience.
ultimate, stock injectors, my fuel press about 50#'s

ostrich, 50#, my fuel press 42#'s, (this is what hood said he runs with a sim build)
so i have been with that, and i can tune my afrs to anything.

your are going to have to find a happy medium, good idle and enough fuel up top to avoid the knock.

i HAD to switch to ostrich: with just 15 psi of boost, pte44, 50lbers, ultimate, 50psi of fuel press, i was still to lean up top.
 
Re: Fuel Pressure ?????

Thanks guys...
I'm running the ostrich and should be able to tune it to where I need it but it looks like I'll need it at least 40. I did notice a little more knock with the lower pressure so I'll set it to the Flow Rate of the inj. of about 44 and wish for the best.
 

NeedaSY

Go Ahead N Go
Re: Fuel Pressure ?????

So then i should try it set at 50psi and see what my ocome is i know that you can put to mu psi throgh an injector and cause it to fail so i geuss i can try it and see what happens.
 
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