Question about my fuel set up... And fuel pressure issue(totally confused)

PCD_RS · Nov 13, 2008

My fuel set up for my 96 RS-T is:
12:1 FMU
Aeromotive FPR
340cc injectors
255lph pump
New OEM fuel filter
SAFC

Ok SO... I've been reading up on fuel set ups... The 340cc injectors and AFPR are what I just added to the mix. Now does this look wrong to you guys? I read up on some stuff where if I go bigger injectors I should toss my AFPR and get an SFMU... As of now I have no moolah for an SFMU. Also if I were to invest in an SFMU what brand or kind should I get? I know with the SFMU's you can change out the discs and adjust it for idle fuel pressure. That and I did a whole lot of reading on the 255lph pump... Read that it tops of at 120psi or something like that?? Any tips for my set up would be much appreciated :thumb:

My other problem is with my fuel pressure. Ok so when you turn off your car... Is your fuel pressure supposed to drop to zero? Or slowly go back down to zero? Because I go to start my car and check my under-hood fuel pressure gauge it reads 35-40psi ish. BUT when I go to turn off my car the FP stays at the same pressure it was when I had started it. NOW is fuel pressure supposed to drop to zero when I turn off the car? Or slowly drop down to zero? Because my gauge SO VERY SLOWLY drops back down to zero. No clue what's going on

. Advice here would be awesome too and much appreciated! TIA

rstare · Nov 13, 2008

PCD_RS said:
My fuel set up for my 96 RS-T is:
12:1 FMU
Aeromotive FPR
340cc injectors
255lph pump
New OEM fuel filter
SAFC

Ok SO... I've been reading up on fuel set ups... The 340cc injectors and AFPR are what I just added to the mix. Now does this look wrong to you guys? I read up on some stuff where if I go bigger injectors I should toss my AFPR and get an SFMU... As of now I have no moolah for an SFMU. Also if I were to invest in an SFMU what brand or kind should I get? I know with the SFMU's you can change out the discs and adjust it for idle fuel pressure. That and I did a whole lot of reading on the 255lph pump... Read that it tops of at 120psi or something like that?? Any tips for my set up would be much appreciated

My other problem is with my fuel pressure. Ok so when you turn off your car... Is your fuel pressure supposed to drop to zero? Or slowly go back down to zero? Because I go to start my car and check my under-hood fuel pressure gauge it reads 35-40psi ish. BUT when I go to turn off my car the FP stays at the same pressure it was when I had started it. NOW is fuel pressure supposed to drop to zero when I turn off the car? Or slowly drop down to zero? Because my gauge SO VERY SLOWLY drops back down to zero. No clue what's going on . Advice here would be awesome too and much appreciated! TIA

An adjustable FPR and fmu accomplish the same thing as an sfmu. All an sfmu does is allow you to control idle/static fuel pressure as well as tweak with the rising rate. The problem is your rising rate. Now that you have bigger injectors you don't need a 12:1 rising rate. That's why an sfmu is nice because it allows you to tweak the rising rate anywhere from 2:1 - 7:1.
Now do you just have an AFPR or a RRAFPR? It's very probable that you have a 1:1 Aeromotive AFPR which also raises your fuel pressure according to boost.
Are you still using your stock FPR?
I suggest putting your stock injectors back in and getting an sfmu.
Vortech is the only place that sells them as far as I know.

The 255lph hp pump tops at 140psi, but at 140psi you only get like 4 gallons per hour. 120psi is about the highest pressure you can be at and still get an adequate amount of fuel.

Think I got it all...

96TurboGS · Nov 13, 2008

For the 340cc injectors get something like a used 8:1 fmu of ebay and fine tune it with the safc. 12:1 for those 340's is going to make you pissy rich once you go into boost. As for the fuel pressure dropping rapidly or slowly I think depends on what type of –an/stock line you have. As you stated you do have a new fuel filter along with the walbro so flow shouldn't be a problem unless you have some sort of restriction/kinks in your line. (Just make sure when you cut the car off the pump is off also) If you think about running more then 10 psi then you might want to look into a sfmu, they work miracles; I still use mine eventho im MS. I agree with rstare I wouldn't drive your car with those 340's untill you get the proper regulator.

PCD_RS · Nov 13, 2008

rstare said:
Now do you just have an AFPR or a RRAFPR? It's very probable that you have a 1:1 Aeromotive AFPR which also raises your fuel pressure according to boost.
Are you still using your stock FPR?
I suggest putting your stock injectors back in and getting an sfmu.
Vortech is the only place that sells them as far as I know.

The 255lph hp pump tops at 140psi, but at 140psi you only get like 4 gallons per hour. 120psi is about the highest pressure you can be at and still get an adequate amount of fuel.

Think I got it all...

I have an Aeromotive 1:1 FPR and I am not using my stock FPR anymore, it's already in the land fill as we speak or scrap yard.
I still have my stock injectors, but if I do that would I still be able to use the Aero FPR and 12:1 FMU with the stockers in? I have re-built the bottom end with 8.8:1 comp and Eagle rods. But I still only have my 5lb spring for my external WG. Just thought I'd add that info in. I was planning on running 8-10lbs but I don't think I will yet until I have more influx of cash. That and the SFMU will have to wait a while. So just wondering if it is still able to run stock injectors with the Aero FPR and 12:1 FMU?? If not then shoot dang I'm screwed until I have money. :mad:

96TurboGS said:
For the 340cc injectors get something like a used 8:1 fmu of ebay and fine tune it with the safc. 12:1 for those 340s is going to make you pissy rich once you go into boost.

Like pissy rich as in detonation rich :barf:

?? Or just pissy rich?

Thanks guys for the replies!

96TurboGS · Nov 13, 2008

Rich as in too much fuel. When you run 12:1 on stock injectors I wouldn't run above 8 psi, because the strain on the stock injectors is too much. It's doable but you wouldn't want something like a stuck open injector. If you're going to get the boost bug and run above 8 psi; upgrade the injectors. A fuel pump rewire wouldn't hurt...

PCD_RS · Nov 13, 2008

96TurboGS said:
Rich as in too much fuel. When you run 12:1 on stock injectors I wouldnt run above 8 psi, because the strain on the stock injectors is too much. Its doable but you wouldnt want something like a stuck open injector. If youre going to get the boost bug and run above 8 psi; upgrade the injectors. A fuel pump rewire wouldnt hurt..

Ok fuel pump rewire... By that what do you mean? I have read some stuff about it, but am not too entirely sure by re-wiring it means..?

rstare · Nov 13, 2008

PCD_RS said:
I have an Aeromotive 1:1 FPR and I am not using my stock FPR anymore, it's already in the land fill as we speak or scrap yard.
I still have my stock injectors, but if I do that would I still be able to use the Aero FPR and 12:1 FMU with the stockers in? I have re-built the bottom end with 8.8:1 comp and Eagle rods. But I still only have my 5lb spring for my external WG. Just thought I'd add that info in. I was planning on running 8-10lbs but I don't think I will yet until I have more influx of cash. That and the SFMU will have to wait a while. So just wondering if it is still able to run stock injectors with the Aero FPR and 12:1 FMU?? If not then shoot dang I'm screwed until I have money.

Like pissy rich as in detonation rich ?? Or just pissy rich?

Thanks guys for the replies!

It would seem that if you got your idle fuel pressure to about 50psi then you could run the RRAFPR and the 12:1 fmu, with your stock injectors. But, don't quote me if you can't. I'm not sure having how having two rising rate regulators will affect your setup. I would try it.
Dentonation comes from being too lean usually.
Lean = less fuel
Rich = more fuel
Stoichiometric = 14.7:1

Edit: Here's the pump re-wire.
2GNT.com - Fuel_Pump_Re-wire

96TurboGS · Nov 13, 2008

http://www.dsmtuners.com/forums/art...14-2g-fuel-pump-rewire-pictorial-diagram.html

Before doing any of that make sure you get your ignition/fuel probs worked out.

Do you have any CEL's?

PCD_RS · Nov 13, 2008

rstare said:
It would seem that if you got your idle fuel pressure to about 50psi then you could run the RRAFPR and the 12:1 fmu, with your stock injectors. But, don't quote me if you can't. I'm not sure having how having two rising rate regulators will affect your setup. I would try it.
Dentonation comes from being too lean usually.
Lean = less fuel
Rich = more fuel
Stoichiometric = 14.7:1

Ok, so I'm gonna throw stockers back in with the AFPR and FMU and see what I can do there.

I know what lean and rich are... But I thought I remember reading something about detonation at being too rich too?? Correct me if I'm wrong.

96TurboGS said:
Do you have any CEL's?

I do have a CEL, but last time I checked it was for a bad 02 sensor on my downpipe 'cause I ran seafoam through it once and I think it killed it ish.

96TurboGS · Nov 15, 2008

Read up: Engine knocking - Wikipedia, the free encyclopedia

If you haven't got it scanned since you got the timing done, you might want to do so.

PCD_RS · Nov 16, 2008

I got it scanned... And it didn't find any codes.. And no CEL anymore, which is weird. So I don't know. Guess I should replace the downpipe 02 sensor since it was detroyed by seafoam when I ran it through when it was N/T.

rstare · Nov 18, 2008

Detonation is when you get mulitiple flame fronts (rather then the one you get during normal combustion) then they colliding and cause massive pressure spikes which will break things.
Dentonation originates from excessive cylinder heat.
If you want to know the extents of it you can pm me.

rstare · Nov 19, 2008

I just saw you have a wideband.
When you start your car and its cold, what is your AFR?

4UH8ERS · Nov 19, 2008

There is no need to run both the aeromotive 1:1 and the 12:1 fmu. Your set-up is rather simple and your complicating things. For now, just install the stock injectors and the 12:1 fmu. A fuel pump rewire is good to do anytime your using a high flow pump. When you decide to raise the boost later, evaluate your variables then and decide then the route you will take.

PCD_RS · Nov 19, 2008

rstare said:
I just saw you have a wideband.
When you start your car and its cold, what is your AFR?

I somehow flooded my cylinders with fuel... So I'm leaving it to dry up overnight.. I tried to start her today and she didn't spark, and when I turned the key to off I heard a BIG POP!! coming out my exhaust (backfire is what I presume). Went under the car and all I smelled in the exhaust was gas; no exhaust smell just gas. So I'm letting it all dry up and hope tomorrow it will be ready to be fired up. So no wideband readings right now.

4UH8ERS said:
There is no need to run both the aeromotive 1:1 and the 12:1 fmu. Your set-up is rather simple and your complicating things. For now, just install the stock injectors and the 12:1 fmu. A fuel pump rewire is good to do anytime your using a high flow pump. When you decide to raise the boost later, evaluate your variables then and decide then the route you will take.

Thanks for the advice 4UH8ERS. So... I don't have my stock FPR anymore... Would that make things mess up? Or would it be ok with just the 12:1 fmu and re-wired fuel pump?

rstare · Nov 20, 2008

In your case you need the 1:1 afpr, because you don't have your stock fpr. Agian I'm not sure if having two rising regulators have a bad effect on things, but I would think your fine.

I assume you have put your stock injectors back in...
Because if you leave those 340cc's in your going to keep flooding it. You might need some new plugs now too. I would pull them out and take a look, their probably black as hell.

PCD_RS · Nov 20, 2008

yea i know theyre black as all heck. i bought new plugs and going to see whatll happen today. man wiah i hadnt thrown away my stock fpr. i really messed things up for myself.

and yes i have my stock injectors back in.

Flipboi89 · Nov 20, 2008

You can run stock injectors at 9 psi. Just your like fully using them and maxing them out. And you won't need that fpr at ony 9psi. Im at 7 psi with just a 12:1 fmu and stock injectors.

PCD_RS · Nov 20, 2008

well the thing is flipboi is i dont have my stock fpr anymore and hoping itll run with 2 rising rate regulators... itll run but i dont know how it will.. i feel like im gonna mess something up :cry:

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