okay soo as sum of u know ive been having problems with my fmu not giving me fuel pressure up top and stuff soo i called up corky at bell engineering and he said i can send out the fmu and he will rebuild it for 30 bucks...orr should i just ditch the fmu and get 440cc deastchwerks? would i get more hp gains or anything with bigger injectors over a fmu?? or it doesnt really matter?

 

dont send your fmu to him. what year is your car?

 

The FMU will give you better startup and idle since you won't be using huge injectors. What are you tuning with? I'm 3.5 and I use 440's with a 3:1 FMU disk, and my fuel delivery is spot on.

It's up to you, but you may wind up sacrificing driveability with bigger injectors. If your only around 300whp, stock injectors are fine when paired with the correct FMU size. Do you have an adjustable FPR? Look into that, it helps greatly. I suggest you jump on Summit racings site, and order a Vortech FMU Calibration kit, comes witha variety of disk sizes for the FMU, and will allow you to make the right choice, good luck.

 

Agreed. No tuning required either.

From my experience, I have no driveability issues, even with 550's. It's all about the tuning.

Also, the OP has a Cartech FMU. Are Vortech's discs compatible? I doubt it.




Again, for the cost of the rebuild plus $10 extra bucks, you can pick up a good used Vortech FMU on ebay. I'd go that route for now. Make sure your car is running like it should, before you start replacing injectors/future mods; otherwise you'll have a troubleshooting nightmare.

 

so wait wizard ur saying for like 50 bucks i can pick up a good vortech fmu?

 

btw my car is a 1995 and y not send my fmu to him?

 

Yes, that's exactly what I'm saying. In the past, I've seen them go for that price on ebay.....and around here too.

 

Well, I wasn't sure what he was tuning with. I'm assuming a AFC won't cut it with bigger injectors, something like an EU would be much better suited.

Also I was unaware it was a Cartech, it was early :P. I say you do what Wizard says, and sell the cartech. Pickup a cheap vortech on EBay or craigslist, and buy the recalibration kit. For the power levels you seem to be going for, stock injectors would be your best bet.

 

The Vortech FMU is non-adjustable (besides the discs inside) which means it's headache and tuning free. I've also heard of Cartech's needing rebuilds after a while, but never a Vortech unit.

I'm sure the Cartech is a great unit, but you have to know how to use it properly since it's adjustable. For someone like yourself who is just getting started, IMO I'd go with the simpler and easier Vortech FMU.

 

well im not doing the tuning and adjusting everything is being dyno tuned and adjusted..

 

At your current power level, everything can be accomplished with the Vortech FMU, no need for Cartech FMU IMO. Why introduce a variable that doesn't need to be there??? Keep things simple. Once you up the anti and start dropping pulley sizes, bigger injectors etc, then it may be time to change things up.

 

because he wants to make a quick 30 bucks off of you. what you can do is send your ecu to jimwolf technology and have them program your ecu for a supercharger program and look for some 370cc injectors and z32 maf and you can ditch the fmu and run your jwt ecu with with that set up and just drive the car. thats just what i would do.

 

Ante*

I agree though, keep things as simple as possible. It'll save you many headaches.

 

Thanks Ptatohed, err...I mean 98Maxedout

 

yeah but y ditch it if i already have it...plus im just running the setup i have now for the winter..im going big numbers soon as spring comes...y sell it then try and buy one again and go threw that hassle...

 

if you get the jwt ecu upgrade then you wont need the fmu thats why i said you can ditch it.

 

A) I didn't tell you to get rid of the Cartech FMU. Keep it for future use when you go 'big' and have more experience/knowledge behind you. But, when you go 'big', most likely you'll longer be using a FMU anyway, so why care?
B) It's more than likely causing your problems, and it sounds like you're unfamiliar with how to use it/adjust it. More gizmo's/adjustments is not always better IMO.
c) Being boosted isn't cheap, but I figured you could afford $40-$50 more dollars; especially if you're going 'big' in the spring.

 

I needed an FMU with the JWT tune and I was running the 370cc.

 

Raising the fuel pressure really wont help much if the stock inj. are already reaching 100% duty cycle.

 

What power are you currently making?
Have you considered maybe you current injectors arent functioning 100%?

 

i think you should go with the bigger injectors. whats the ratio of the fmu? i had a 8:1 boostin 8psi on stock injectors thats 100+ psi fuel pressure even though i have a walbro 255 you shouldn't run that high fuel pressure. i got rid of the fmu and got an afpr and 370cc injectors.

 

i owuld get the 370's but i have dek top feeds

 

Get an adjustable fuel pressure regulator, and you're done worrying.

 

Combined with the Cartech FMU, he'll have more adjustability than he knows what to do with!! lol

 

Nismo FPR, coupled with Vortech FMU = Plug-n-play tuning for noobs!

 

i know how to adjust the cartech thats not a problem its just when i try to raise the pressure it doesnt raise..the cartech itself is messed up thats y im ganna send it out and get it rebuilt

 

Which model do you have??
Types of Regulators
PN: 2025 Aftermarket turbo and supercharger (1/8 NPT)
PN: 2027 Hi-Flow aftermarket turbo and supercharger (1/4 NPT)
PN: 2022 Factory (OEM) turbo and supercharger

Also...did you see this?

Trouble Shooting

1. Jams at maximum fuel pressure:

The regulator is installed backwards.

The center screw in bottomed out inside and must be backed off.

2. Pressure doesn’t rise:

No signal.

Signal is blocked.

Pump won’t make any more than that pressure, close the fuel return line to verify.

The check valve is stuck open. Test by closing the needle valve and sucking on the signal line. It should be a dead end.

3. Pressure rises, but not enough:

Close the needle valve.

Increase the center screw (static) adjustment.

Check the pump again, but remember, it will have less pressure at high loads, than at idle.

Remove the restrictor.

4. Pressure rises, but too high:

Open the needle valve further.

Back off the center screw somewhat.

Add the restrictor.

Check valve is installed backwards.

5. Fuel pressure oscillates:

Slow oscillation of ~1 Hz can result from the regulator being installed backwards.

Faster oscillation, more like a buzz, but without the noise, is usually induced by a rapid pulsation from the fuel pump. Not much can fix it short of a different brand of pump or a pulse damper. The condition is not harmful at boost pressures of 8 psi or less.

If buzzing is audible, turn the center screw 1/4 turn, and it ususally ceases.

 

what happened on the dyno was as soon as he stomed the throttle the pressure would rise but it would get stuck at like 63psi and the motor would start leaning out like crazy...we tried like every adjustment possible on the cartech and nothing was working

 

**edited**
I just saw your sig, so at 5k is where your FP maxes out at?

 

yeah around 5k give or take sum but we would watch the fp gauge rise then it would just stop and then he left off cause it was leaning out reallyy bad and he didnt wanna blow up my motor

 

max out at 5k what kind of fuel pump do you have

 

you dont need to use it.

 

I think I did.
When I dynoed at 5k+ my AFR's were in the high 12's to 13's all the way to 7K, you dont think I needed it?
That was with the JWT ECU, I bought the ECU from Stephen Max, and he had the same issue.

 

I read in your other thread that your maxing out at 60psi at 5K.
I did some runs today and going WOT I hit around 62psi at 6500 and at 5K im seeing around 52psi, well under the 60psi your seeing. So it seems like the FMU is raising your FP.
What psi do you see at 5k and 6500 Wizard?
You might want to try installing a different disk and to see what it does.
You might just be maxing out your injectors. IDK
I know when I replaced my Walbro, it wouldnt go over 50psi, but like I said I hit that 50psi at around 5k.

 

yeah but flava dont u have bigger injectors??

 

okay i got sum great news FINALLYYY!!! okay i took apart my fmu cleaned everything up put it back together and installed a different walbro 255 pump i had and just went out to get dinner and on the way back i punched it and hit about 5300 rpms and it didnt lean out soo im like 99.9 percent sure its fixed but ill keep everyone posted if im not....btw whoever had this cartech fmu before me i think ****ed it up b4 he gave it to me...i found rtv sealant ALL over the top of the disc inside the fmu i was like wtff!! and one of the washers were just laying inside the fmu...soo kid i bought the kit from ur a moron...idk his name or if hes actually a member on here but hes a retart. time to get tuned!! round 2 haha

 

btw thanks wizard,flava and all u guys for helpin me out givin me sum tips on what it could be...+1 for u guys

 

Good to hear, BUT remember you will need to address the injector issue soon adding more fuel pressure to them is only a band.
Simply adding more fuel pressure to the injectors isnt going to make them flow more then they mechanically can and you may run into issues again once you begin dynoing.
Ive always read that you dont want to push the injectors pass the 60psi mark, which you will be greatly doing if your already hitting 60psi at 5K rpms.
Pushing the injectors to there limits will surely shorten there life and lead to injector failure.

 

yeah eventually im getting 440's or 550's

 

okay this car is frigin driving me nuts!!!! i just took my friend for a ride and had him watch the wideband as i went to redline and he said as soon as it got to like 5200 it started leaning out bad!! but i had the cartech center screw backed out alll the way and the bleeder screw backed out all the way soo ima try putting the center screw in like half way and the same with the bleeder valve maybe thatll work.....btw my fuel setup is walbro 255 = z32 fuel filter = stock 5th gen fuel rail damper = fuel rail = stock fpr = then it goes to a gauge i have attached to the inlet of the fmu = fuel tank...now when i squeez on the line after the fmu to the fuel tank the gauge b4 the fmu goues up to about 65psi and doesnt go any higher...and when i pull the vacumm line off the fmu i turned the screw in about half way and the pressure rose to about 53psi