fuel pumps and injectors

[tylermartindc]

trying to decide on choosing new pump and injectors. my mods are in my profile for u to have a look. my question is, with the minimal mods i have, is getting a fuel pump such as walbro 255lph too much ? is it safe to run that considering what i have? and also how to choose injector size? im running around 12psi as of right now but the owner before me said it could run on 15psi. i dont see how it could have "safely" with stock pump and injectors.
any input is great.
thanks , tyler

 

[VelocitàPaola]

Your car can run up to about 16psi with the stock fuel system and minimal supporting mods (MBC, boost gauge, etc.). If your goal is only 15-16psi, I wouldn't touch a thing.


And... there is no such thing as "too much," when it comes to fuel pumps. You might never realize the full potential of a Walbro 255, but it won't over-pressurize your fuel lines or anything; that's what an FPR is for.

As for injectors, it all depends on your goals for the car - get back to us with what you want your car to be able to do, and we'll be better able to tell you what you need.

 

[zippyshoe]

You may already be aware of this, but if you decide to get a Walbro 255, be sure you get an adjustable FPR to go with it as VelocitaPaola mentioned. If you decide to get upgraded injectors, you will also need to buy some type of fuel control product to control these bigger injectors.

 

[tylermartindc]

thanks guys, yeah im just looking to run a little more power, safely without risking damage. i use my car as a daily driver, and take it out for some spririted driving once in a while. i am as u know a "newbie" to this turbo game. any suggested or common injector sizes for my intents and purpsoses? a question about an apexi safc, is this just for monitoring, or can u actually make adjustments from this product? i think i may be getting the right idea of what to get next.
tyler

 

[crunchymilk]

afc is for making a/f adjustments, you'll need a datalogger to watch what's going on inside the engine though. When it comes to injectors, it entirely depends on how much power you want to make, and with which turbo. The stock system can handle 15psi or so just fine, but it usually won't hold to redline with that small T25 stock turbo. Research a little bit, check on tuner's mod guide, it's very helpful. Let us know your goals, "a little more power" isn't enough info.

 

[tylermartindc]

alright to narrow down what i want to do you could call it "stage one" from the tech guide. i see now that it tells me essentially what i need to get if i still want to keep my stock turbo, which i do. i have a path now and would just like some input maybe or some pointers from ppl who have gone thru this step before. for example, what parts, brands, things to watch out for.
thanks a lot
tyler

 

[Jordanbutter]

Hey Fuel Injector Clinic Has got (4) 650's, a new rail, and an Areomotive FPR for $525!

http://www.fuelinjectorclinic.com/cart/mitsubishi.htm

Also you can get Walbro 225 from Extreme PSI for $95 (cheapest i've seen)

http://www.extremepsi.com/store/customer/product.php?productid=16272&cat=430&page=1

Of course theres always E-bay!

 

[packinkimber45]

dont mean to interupt, but I bought a 90 talon tsi awd that has walbro 255. however no upgraded fpr or upgraded injectors. is that bad? thanks

 

[VelocitàPaola]

No, zippyshoe was a little misleading... you don't need an AFPR with only an upgraded fuel pump. Your stock FPR will regulate the fuel pressure accordingly.

 

[oldman]

No, zippyshoe was a little misleading... you don't need an AFPR with only an upgraded fuel pump. Your stock FPR will regulate the fuel pressure accordingly.

Paul, you do need an AFPR. Since the stock fpr is none-adjustable, any fuel pump that flows more than the stock pump WILL overrun the stock fpr. You can get away without one on the 190 unit most of the time but an AFPR is definitely needed for the 255.

 

[2gGSX]

Almost everyone else will disagree that a stock FPR won't overrun with a pump as large as a Walbro 255 hp un/rewired.

edit: Beaten to the punch!

 

[packinkimber45]

what would happen if this kind of set up is used for a while? (walbro 255/no upgr. injectors/no afpr) Reason I ask is I dont know how long this car has been running this way for. car is running 15 psi also. my mods are listed on my profile.

 

[oldman]

what would happen if this kind of set up is used for a while? (walbro 255/no upgr. injectors/no afpr) Reason I ask is I dont know how long this car has been running this way for. car is running 15 psi also. my mods are listed on my profile.

FPR overrun will cause rich conditions during idle and part throttle, rough idle, stalling, poor fuel economy and making tuning extremely difficult. Simply put, overrun occurs when the stock fpr is unable to bleed off the extra volume of fuel from a larger pump in order to 1) pull pressure down to stock setting and 2) maintain 1:1 fuel to manifold pressure ratio until the engine is under enough load to use up the extra fuel, since load is based on multiple factors, it's impossible to tune out FPR overrun.

As for possible damage, worst case scenario, fuel washing down the cylinder walls mixing with oil.

 

[VelocitàPaola]

Paul, you do need an AFPR. Since the stock fpr is none-adjustable, any fuel pump that flows more than the stock pump WILL overrun the stock fpr. You can get away without one on the 190 unit most of the time but an AFPR is definitely needed for the 255.

Uh??? If you say an AFPR is necessary, Bruce, then it must be necessary - I won't argue with you. However, I've never met any 4G63 owners who actually experienced FPR overrun just from upgrading their fuel pump... The 420As, at least, don't have this problem; I would've thought that if our modest N/T FPRs can properly adjust for higher fuel pressures and flow rates, then surely the turbo versions can too. I'm just reasoning out loud, though: listen to Bruce or you'll leave a thick trail of soot everywhere you go.

 

[nightspeed87]

what if you have a n/t regulator and a 255 and stock injectors and boost turned up like 1 or 2 pounds more?

 

[nightspeed87]

since the n/t regulator has more psi does that mean its also more capable of dealing with more psi from the pump? or do i have it backwards and it means it will deal with less?

 

[VelocitàPaola]

Wow. That's a pretty specific question. Unless someone else has experience with that exact setup, I suggest you invest in a wideband O2 sensor/controller and find out yourself.

Let me make sure I'm fully understanding you, though. You have an N/T FPR in a now turbocharged car? N/T FPRs aren't designed to raise the fuel pressure under boost; they generally only operate under vacuum (unless Mitsubishi tried to cut costs and used the same FPR for turbo and N/T 1Gs). Are you using some sort of FMU to compensate for this? If not, I'd imagine you're running extremely lean.

 

[nightspeed87]

Wow. That's a pretty specific question. Unless someone else has experience with that exact setup, I suggest you invest in a wideband O2 sensor/controller and find out yourself.

Let me make sure I'm fully understanding you, though. You have an N/T FPR in a now turbocharged car? N/T FPRs aren't designed to raise the fuel pressure under boost; they generally only operate under vacuum (unless Mitsubishi tried to cut costs and used the same FPR for turbo and N/T 1Gs). Are you using some sort of FMU to compensate for this? If not, I'd imagine you're running extremely lean.

my car isnt running yet, did a motor swap from a n/t 4g to a turbo 4g63... 255 lph goin in, and ive read that the n/t fuel pressure regulator actually has 10 psi or so more pressure than the turbos fpr on the 1g cars. Ive read some guys running n/t regulators for addition pressure ( for whatever its worth. ) I was only running it because thats the only fpr i have to install at the momment since mines used to be a n/t 1g. But it gives off more pressure, so do you think this would encourage or delay fpr overrun?

 

[nightspeed87]

and no fmu and stock injectors, boost is going to be raised a few pounds, and the interals are fully built and ported polished and cryotreated. 3 in exhaust back no cat, and KnN filter, and bigger side mount ic pipeing. But thats all i have for now if that helps give you a better picture.

 

[oldman]

Uh??? If you say an AFPR is necessary, Bruce, then it must be necessary - I won't argue with you. However, I've never met any 4G63 owners who actually experienced FPR overrun just from upgrading their fuel pump... The 420As, at least, don't have this problem; I would've thought that if our modest N/T FPRs can properly adjust for higher fuel pressures and flow rates, then surely the turbo versions can too. I'm just reasoning out loud, though: listen to Bruce or you'll leave a thick trail of soot everywhere you go.

Paul it's physically impossible not to overrun the stock fpr with a 255 in a 4g63 unless you have either a defective pump or leak/leaks in the system. I will gaurantee that if any of these guys were to install a fuel gauge, they will find out that it's no longer running at stock setting at idle, by definition this is fpr overrun. Also keep in mind that having overrun and noticing it are two different things, many of the symptoms of overrun can either be blamed on something else like boost/vacuum leaks, bad o2 sensor, vented bov.....etc. or compensated somewhat with tuning while wondering what tune keeps changing from day to day/run to run. I honest have never met or read on here that someone with 255 w/o afpr having perfect stock reading on a fuel pressure gauge, most of them do not even have a fuel pressure gauge.

 

[VelocitàPaola]

Also keep in mind that having overrun and noticing it are two different things

This is true; I thought the same thing myself, after I made my previous post.

 

[DSM90AWD]

I ran a rewired 190LPH walbro for years with a stock FPR and experienced no overrun (monitored via my TMO datalogger's LTFT values) and it supports ~420HP. So if you're sticking with the stock turbo for a while or even plan to run an EVOIII 16G this would be the pump I'd recommend without the need to spend an extra $200+ on an AFPR.

Then again, an AFPR can extend the HP range of your stock 450cc injectors:
Stock 38psi = 423cc = 270HP
43psi = 450cc = 285HP
50psi = 485cc = 308HP

Note there are diminishing returns to running high base FP both in terms of injector performance and pump performance (pumps deliver less at high pressures), but gives you a general idea

 

[TSIMonsteR]

mmm... I am kinda going through the same delima. I have an EPROM ECU on the way, so I have already decided on injectors and DSMLink. But the whole fuel pump and afpr thing has got me stumped. I can't decide. It's just so tempting to get the 190 with no afpr b/c its cheaper. At the same time, I do not want to have to install/buy fuel pumps twice (if I find the 190 isn't enough)

 

[SinaiTSi]

mmm... I am kinda going through the same delima. I have an EPROM ECU on the way, so I have already decided on injectors and DSMLink. But the whole fuel pump and afpr thing has got me stumped. I can't decide. It's just so tempting to get the 190 with no afpr b/c its cheaper. At the same time, I do not want to have to install/buy fuel pumps twice (if I find the 190 isn't enough)

I'm kinda in the same boat. I will be upgrading to an Evo3 16g as well in the near future and I've been told to just go with the 255, yet I think i'd rather just get a 190 so I won't have to worry about an afpr. But after what DSM90AWD said, I'm leaning even more towards a 190. Just curious, what turbo do you plan on running and what injectors have you decided on? I'm also trying to decided on injectors myself as well.

 

[nightspeed87]

me three... Thats why i just gone and opted for the 255. Im going to have tuning equipment soon so i figured I might as well just get the best one.