Need help FAST!!! Car is running lean under boost

Okay this is my set up for fuel and stuff:
Paxton 10:1 FMU
B&M Adjustable FPR
Missing Link

It was running great for a few weeks until about an hour ago. my A/F guage always stays in the green, ocassionaly it will get one orange bar with the rest green. (Autometer Ultra Lite A/F guage)

so this is what happens.....

When Im driving and my boost gets between 3-5+psi my A/F guage drops right down to the last red light (is green until then, btw guage only works at WOT) and you can feel the car like stop pulling hard and you know its running real lean.


I do not have a fuel pressure guage. the car idles fine, pulls great until then. I was thinking fuel pump for a bit (because of rasing the pressure so much - figured it might of nuked it) but I wouldnt think it would work this good until then. other thing I am thinking of is maybe my FPR craped out? what would crap out in them though? all the Vaccum lines are connected and pulling vaccum.


What do you guys think? It was working so good and then just started doing this. I am running aprox. 7psi.

Help me out guys I need to get this fixed asap before anything bad happens

first I would say make sure you fuel filter isnt stopped up, you might just need a new one, if that doesnt work it might be that you need a high pressure fuel pump, but since you said it was sudden it sounds more like something is restricting the fuel flow from getting to the fuel rail when alot is needed so it sounds like maybe the filter.

Fuel Filter is OEM Honda, not even a week old, put it in last thursday. Think it may be clogged already? I always use 94 octane and usally never run past 1/2 tank.

Kyle

Probably because your running an FMU and missinglink together. The FMU needs to see the boost to know to up the fuel pressure while in boost. Really depends how you have the vac lines hooked up, make sure your not pulling the vacuum/boost pressure from the missing link line on the FMU. Missinglink is just used to fool the map signal.

You need a fuel pressure gauge. What fuel pressure are you running? What injectors? I will stongly reccomend a high pressure fuel pump\ as well

Well with a FMU you need a Missink link so that the computer goes not see the boost. The vaccum/boost line I am using for the FMU if T'd off of the Brake booster line (to make sure it was big enough, then use a 6mm hose to the FMU)

There is no possible way to pull vaccum from the Missing link as it is bolted right to the Intake manifold.

All the Vaccum lines are still connected and yes they are clamped (wire ties)

Like I said before it was working great until just the other day when I was playing around it started happining so I know something broke/stoped working.

I am running stock fuel pump and injectors although I just ordered a Walbro 255 pump. and Yes I have stock injectors

I am unsure of the fuel pressure I am running because a fuel guage to mount inside the car is $200 and well I cant afford that. It would do me no good with a guage mounted in the engine compartment as I would not be able to see the pressure under boost.

It really seems like the FMU craped out because it isnt noticable until it starts to boost up then it just does this, and I know its not the 02 sensor because I ran the car a few times without a 02 before i had the downpipe made and it did not to this, and it did not ping.

make sure your fmu isnt leaking air. There is a diaphram inside it that has to have a seal to make it function properly. If it is holding pressure you might want to disassemble the fmu and make sure something isnt keeping the lower diaphragm from making a seal and keeping the fuel pressure from rising. Also make sure the piece of metal that puts pressure on the lower diaphragm isnt sticking inside the bore. If none of that helps then the only other thing I could think is the pump.

Well with a FMU you need a Missink link so that the computer goes not see the boost. The vaccum/boost line I am using for the FMU if T'd off of the Brake booster line (to make sure it was big enough, then use a 6mm hose to the FMU)

There is no possible way to pull vaccum from the Missing link as it is bolted right to the Intake manifold.

All the Vaccum lines are still connected and yes they are clamped (wire ties)

Like I said before it was working great until just the other day when I was playing around it started happining so I know something broke/stoped working.

I am running stock fuel pump and injectors although I just ordered a Walbro 255 pump. and Yes I have stock injectors

I am unsure of the fuel pressure I am running because a fuel guage to mount inside the car is $200 and well I cant afford that. It would do me no good with a guage mounted in the engine compartment as I would not be able to see the pressure under boost.

It really seems like the FMU craped out because it isnt noticable until it starts to boost up then it just does this, and I know its not the 02 sensor because I ran the car a few times without a 02 before i had the downpipe made and it did not to this, and it did not ping.


Its ez to see what your fuel pressures are with a gauge under the hood, when you adjust your fuel pressure, you hsould take off the vacume line that goes to your adj regulator. That will give you your max fuel pressure settting. Besides why would it cost your 200 bucks for an in compartment fuel pressure gauge? Go buy an autometer or whatever brand you use and the sender unit that makes it legal to be in your passenger compartment. it will be about 90 bucks once all said and done. For a turbo car, espically one that was not ment to be turbocharged, you need to keep an eye on all fuel readings at all times if you want an engine to live

The Autometer Electric 0-100 psi fuel pressure guage is 190$ you can get a regular mecanical style guage for like 40 but they do sell a thing to convert it for about $100 but i hear its not as acurate as a real electric one.

I know how to cheak fuel pressure at idle and stuff but I need to pull boost on the FMU for it to raise the pressure and I only have a vaccum pump so I cant push boost on it unless it is under full throttle under load.

Kyle

Okay I just put in a new FMU with a 12:1 ratio and yup same thing.... there was a waste of money okay next thing I am going to try is a new Walbro 255 fuel pump. Anyone else have any ideas? only other thing I can think of is the filter got clogged/defective or I got a crushed fuel line... but I did not see any damage to my lines and the filter was working great and is just over a week old so I am going to assume it is fine. If the fuel pump doesnt work I guess I'll do the filter again other then that Im out of ideas? I can not find any vaccum leaks, the lines look good, if any of the sensors were bad I think the computer would make it run rich, hell I drove around for a week with no O2 at all and it ran fine, unless the sensor is broking and tellling the computer its rich but the guage says its lean, and i know it is... anyother ideas?

Kyle

I would have to assume it is the fuel pump, the stock fuel pump just was not designed to provide that kind of volume with that amount of pressure. The new pump should fix it. Also have you read the plugs to see how bad the detonation is? You need to do that as soon as you can b/c sometimes the plug itself will get damaged and need to be replaced. Alao it might be able to give you a slight idea of the condition of the pistons and rings. I would also be doing a compression test along with a leak down test if you are on stock internals b/c it might be time for a rebuild after this.