Going lean and bogging in boost

[dsmdragon]

Ok I am trying to figure this out and need help.

I just Got my turbo kit put on my 420a an took it for a run. I noticed that when I hit boost my a/f gauge just went red and i felt a loss of power from 1 to7 psi.

It has a vortec 12:1 FMU
An FCd at 4.6v (that's all i could read on my meter. even though the ins. said 4.63v)
turbo 4g63 fuel pump on it
pump rewire.
My problem is when I hit 7psi or even around 2 or 3 psi my goes lean and the car feels like it bogs or has little power when in boost. other then that the car runs great and the A/f mix is perfect unlrss in boost. What could be the problem?
Do I need a 190lph pump
Does the FCD need to be at 4.63v?
or is there something else wrong, like would a boost leak cause this or do I need more then what I have for fuel mod's etc. Let me know

 

[rstare]

It's probably the fuel pump. The stock 4g63 pump doesn't support the fuel pressures you are seeing. You need a Walbro 255lph hp pump.

 

[tenn-gsx]

7 psi? Cmon thats only ### 50 psi fuel pressure? A turbo pump sees atleast that under stock conditions.

 

[VelocitàPaola]

7 psi? Cmon thats only ### 50 psi fuel pressure? A turbo pump sees atleast that under stock conditions.

The 420A's base fuel pressure is 53psi, and under full boost, the FMU bumps the fuel pressure to 137psi (53psi + 12*7psi). That's likely quite a bit more than the 4G63 pump was designed to handle.

 

[dsmdragon]

so what if i used a a 10:1 or a 8:1 fmu since i am only going 7psi right now and I know by doing my math that that would still give me plenty of fuel for my setup would tht not lean me out like it is... Cause the 12:1 is alot of fuel presure for every pound of boost... And i know I can get better resoults with a lower presure gain

 

[tenn-gsx]

Ok my mistake. I had no idea about the fuel pressure boost. Sending you a pm Im curious now.

 

[VelocitàPaola]

The 10:1 might work decently, but the 12:1 is the closest to the required AFR curve. What kind of FCD do you have?

 

[dsmdragon]

I hace a electronic FCD I bought from a guy on 2gnt.com its a black box with an adjustment screw on the side. It doesn't autoTune if that's what you are getting at. ok so I need a fuel pump either way though cuase the turbo pump isn't getting me what i need...

 

[VelocitàPaola]

Hmm... well most FCD's I've seen need to be set to about 4.59V or lower. 4.6V is the cutoff for fuel cut.

 

[rstare]

Doesn't sound like he is hitting fuel cut though.
As I'm sure you know Paul, there is a big difference between running lean and hitting fuel cut. I think he would know if he was hitting fuel cut. Which leads me to think the FCD is unrelated in the problem.

Edit:

ok so I need a fuel pump either way though cuase the turbo pump isn't getting me what i need...

That is what I would start with.

 

[Car_guy_09]

Doesn't sound like he is hitting fuel cut though.
As I'm sure you know Paul, there is a big difference between running lean and hitting fuel cut. I think he would know if he was hitting fuel cut. Which leads me to think the FCD is unrelated in the problem.

Good point...

 

[dsmdragon]

Ok i see the point in the FCD i can try that and see. But like i said I'm going really lean when in boost and it feels like i have no power, less then when i'm not boosting. i'll try the pump and see what that does as well..
Also do you know what spark plug I can run that's colder then oem ones that i can get a autozone or something.
And I think I'm having oil backing up into my turbo cause I'm getting a lot of smoke out the back. Would a 3/8 house do this on the oil return. Do I need half inch.

Thanks for helping me figure this out

 

[VelocitàPaola]

Doesn't sound like he is hitting fuel cut though.
As I'm sure you know Paul, there is a big difference between running lean and hitting fuel cut. I think he would know if he was hitting fuel cut. Which leads me to think the FCD is unrelated in the problem.

Eh... a loss of power at "2-3psi" sounds like fuel cut to me.

 

[VelocitàPaola]

Ok i see the point in the FCD i can try that and see. But like i said I'm going really lean when in boost and it feels like i have no power, less then when i'm not boosting. i'll try the pump and see what that does as well..
Also do you know what spark plug I can run that's colder then oem ones that i can get a autozone or something.
And I think I'm having oil backing up into my turbo cause I'm getting a lot of smoke out the back. Would a 3/8 house do this on the oil return. Do I need half inch.

Thanks for helping me figure this out

A 3/8" return line is pretty small. You really need something 1/2" or 5/8", or 8-AN or 10-AN.

 

[rstare]

Eh... a loss of power at "2-3psi" sounds like fuel cut to me.

Eh.. We have a difference of opinon. I hit fuel cut and I almost smacked my head on the steering wheel, very violent... Thank you seat belt.
Paul, you probably have more experience with fuel cut then me though. I just figured my experience is what fuel cut is, and I don't describe it as a loss of power, more like my car started seizing, .

+1 For what Paul said on the oil return line

And like we previously said, either way you need the 255lph hp fuel pump.

 

[dsmdragon]

K im getting the fuel pump. And i just fixed the oil return ...No more smoke.... Oh I have had fuel cut on other cars before and It felt like hitting a brick wall doing 90 or something. So I'm not so sure it's fuel cut. but what Am am sure about is the fact that I have no power when i hit 3ish or more psi. so the pump will fix it and I'll let you guys know. thanks

 

[dsmdragon]

Hey guys I got the new 255lph fuel pump on my car. But it still is feeling like I hit no power when I get over 2/3 psi. It's not the feeling of hitting a wall, just when at WOT or even 60/70% throttle there's less power then when i'm not boosting at 30% T. I can't figure it out

Also when i put the new pump in, I have to crank my car twice now just to start it. so is this a afpr problem an need to put it on the car. If so can I put the regulator close to my fuel rail. since my return line is in the back of the car, or do I need to put it before the stock fpr?

 

[rstare]

Hey guys I got the new 255lph fuel pump on my car. But it still is feeling like I hit no power when I get over 2/3 psi. It's not the feeling of hitting a wall, just when at WOT or even 60/70% throttle there's less power then when i'm not boosting at 30% T. I can't figure it out

Also when i put the new pump in, I have to crank my car twice now just to start it. so is this a afpr problem. If so can I put the regulator close to my fuel rail. since my return line is in the back of the car, or do I need to put it before the stock fpr?

Wait; you have a AFPR, like 1:1 AFPR (if so, why)? Do you have an 12:1 fmu? What's your fuel pressure at idle? Do you have a wideband? Are you using bigger injectors?
It sounds like your running lean under full boost, by the way you describe it.

 

[dsmdragon]

sorry for not being clear here.
first I don't have the afpr on the car now and was wondering if i needed one on for my idle presure, so I can keep my 1:1 ratio when I go up in to boost. I still have a 12:1 fmu on the car. I have stock injectors and I'm not going over 7psi. So that shouldn't be a problem... So read the last post I wrote with that in mind and could you give me some answers. on the problems I am facting.
Do you think a boost leak could cause that or spark plugs not a range down... afpr problem. What could cause me to have little to no power when i hit 5psi with a 255lph pump and 12:1 fmu.....WTF

 

[totaleclipse_05]

You have the 12:1 FMU under the car by the tank right? I would put a new fuel filter in and see if that helps out as well. Your vacuum line to the FMU from the intake manifold has no leaks?

Sounds like you should have done a little more research into turboing a 420a before jumping right in. Were you blowing into the MAP sensor when setting the FCD's voltage?

 

[rstare]

You missed one question; do you have a wideband?
You don't need a 1:1 afpr at all. The stock fpr takes care of your out of boost fuel pressure.
Do what Mike said; change the fuel filter and check to make sure your vacuum line going to your fmu is okay.

 

[dsmdragon]

Ok well, I did do a lot of Research before i jumped in to this project. And I have done plenty of turbo builds before on friends cars. I am double checking on things so i can get this bump out of my way. Also I here alot of people talk about using a afpr on there cars when using the 255lph pump so stack presure stays in check. That might be for a 4g63 and not a 420a though. That i was not sure about and was checking.

Also I did blow on the map sensor when setting my FCD for fuel cut so I don't have a problem with that at all, but I was told in the directions that it need to be set to 4.63 volts and I have always used FCD's were you set them to 4.5v or lower. I'll try lowering it just to check!

I might have a problem with the vac. line to the fmu if it isn't big enough hose then would that make a problem when air traveling through the line has so far to travel, wouldn't it drop presure to the FMU? I think I have 3/16

 

[rstare]

Also I here alot of people talk about using a afpr on there cars when using the 255lph pump so stack presure stays in check. That might be for a 4g63 and not a 420a though. That i was not sure about and was checking.

Also I did blow on the map sensor when setting my FCD for fuel cut so I don't have a problem with that at all, but I was told in the directions that it need to be set to 4.63 volts and I have always used FCD's were you set them to 4.9v or lower. I'll try lowering it just to check!

I might have a problem with the vac. line to the fmu if it isn't big enough hose then would that make a problem when air traveling through the line has so far to travel, wouldn't it drop presure to the FMU? I think I have 3/16

Yup, that's the 4g63 that needs a 1:1 afpr when upgrading to a 255lph pump.

4.63v is the magic number, over that and your going to throw a code and possibly hit fuel cut. Are you getting any codes?

3/16" sounds small... It should be fine though, as long as there is no kinks, tears, dry rotting, and is connected.

Try the other things Mike and I mentioned and go from there.

You missed the question agian, ; do you have a AFR/Wideband gauge.

 

[VelocitàPaola]

I would also double check the O-ring between the fuel pump and fuel pump assembly. That O-ring is easily dislodged when installing a fuel pump. If it doesn't create a tight seal, your fuel pressure will be rather low, meaning your car will take longer to start while the pressure builds.

 

[dsmdragon]

you know what I had a problem with that o-ring taken it off and putting it on. So that might be it. I'm going to check my vac. line to the FMU 2maro and i might need bigger hose. Do you know how to tell what size disk you have in your fmu by looking at it or taking it apart?
i have a wideband o2 coming so that will help. i'll try your advice and let you guys know. thanks...