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TeH Brown Ninja Turtle
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I have an msd in-line pump, a walbro intank pump, fuel return line, and 550cc injectors and the aem fuel rail if that makes a difference, and yet when i try turning my boost up to 10, the car starts going lean even with the apexi maxed out...does anybody have any clue as to what could be the deal?...im shooting towards the intank pump being messed up any thoughts?...
 

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Buttplugs?
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Is you pressure regulator on tight enough? I doubt that may be it but its worth a try since you said you have the AEM FR.
 

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TeH Brown Ninja Turtle
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Discussion Starter #3
well its not AEM,its SX but i doubt that makes a difference but ya ill check that out....i really think its my intank fuel pump that is bugging considering it was from a DC2 and they modified it for the rsx...
 

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Inprogress2 said:
I have an msd in-line pump, a walbro intank pump, fuel return line, and 550cc injectors and the aem fuel rail if that makes a difference, and yet when i try turning my boost up to 10, the car starts going lean even with the apexi maxed out...does anybody have any clue as to what could be the deal?...im shooting towards the intank pump being messed up any thoughts?...
What kind of electronics are you running? Did you specify injector size properly?
 

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Inprogress, is your FPR boost dependant, meaning that when you increase boost the FPR increase the fuel pressure accordingly, 1:1 ratio? Check also the vacuum line going to your FPR, make sure it is not broken or disconnected. Also at idle your fuel pressure shall be around 58 psi (if you dont have a fuel gauge to measure it, I will recommend you to buy one). Check also that your MSD inline pump is running. Inspect the supply and return fuel lines/connections for fuel leakages, and as you mention check your intank fuel pump. I have the Cyber fuel system with the only difference from your setup that mine have the stock intank pump and I have a Malpassi FPR (boost dependant 1:1). I have boosted my car to 12 psi with no problems, with the A/F gauge solid green, very rich.
 
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Inprogress2 said:
I have an msd in-line pump, a walbro intank pump, fuel return line, and 550cc injectors and the aem fuel rail if that makes a difference, and yet when i try turning my boost up to 10, the car starts going lean even with the apexi maxed out...does anybody have any clue as to what could be the deal?...im shooting towards the intank pump being messed up any thoughts?...
I'm having hte same problem. I was talking to some guys and theyre thinking it might be the AEM fuel rail because its smaller than the stock one. I've been talking to Lee about the problem for awhile now and I replaced almost everything. I redid their intank system a couple times, bought a new inline fuel pump, and checked my electricals a couple times. I'm going to put my old fuel rail back on and I'll let you know.
 

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yeah i have been hearing the same thing from people with the aem fuel rail, might not be flowing as much fuel as the stock fuel rail. keep us updated
 

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this is the thread ive been looking for.

i am a bit skeptical about the aem fuel rail flowing better than stock.
i figured aem is just for looks, just like their brake kit. their rotors are larger but their calipers are nearly the same size as stock, and doesnt utilize maximum area and therefore brakes same as stock. aem pulley only barely pulls 3-5 hp from stock for the price you pay. aem parts for rsx, in my opinion, is just for looks.


in any case, i saw this website http://www.stealth316.com/2-fuelpumpguide.htm
it says upgraded fuel pumps like walbro may not be able to provide fuel at or near maximum capacity just because it is "upgraded" from stock. some have to be modified to get more voltage. if its not getting enough juice, then it wont flow as much and you will run lean. only way to tell is to either get the fuel pump tested at rceng.com or take a fuel pressure gauge and see if you are loosing fuel pressure when you increase boost or when it runs lean at higher rpm. also a fmu may not be able to manage aftermarket fuel pumps to its full potential.
NOTE: this issue applies primarily to those boosting from low-mid to high 300whp range.
 

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oh and i also called walbro. the sales lady their (diana) says the same thing. just because you upgrade the pump doesnt mean it will flow to capacity (this applies to fuel pumps that dont belong to the same application i.e. walbro 255lph pumps from a supra or eclipse into an rsx-s).

i think it could be either it's not getting enough juice (you will have to measure the voltage at the pump with a voltage meter) or the fmu (i.e. bmw/vortech/kpro) isnt managing the fuel pump to its full potential.
 

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and if any one wants to know rsx-ct says "from the Hondata seminar notes posted up here they said the stock fuel pump is good for between 250-290hp. I think you'd be okay." as found here http://forums.clubrsx.com/showthread.php?t=148094&highlight=fuel+pump

and a quote directly from hondata
"I [hondata] suggest you install a fuel pressure gauge when you have close to 300 HP. If the fuel pressure starts dropping at the top of the rev range, get a new pump."
 

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true, you are right. i say get rid of the fuel rail. but also buy a fuel pressure gauge and test the car at the fuel rail...if pressure drops when you rev to higher rpms, it means the car is not supplying enough fuel. it is either due to pump or fuel rail or fuel lines. you'd have to test pressure before and after removal of the fuel rail to know if the fuel rail is hindering fuel delivery.
 
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jnavarro said:
true, you are right. i say get rid of the fuel rail. but also buy a fuel pressure gauge and test the car at the fuel rail...if pressure drops when you rev to higher rpms, it means the car is not supplying enough fuel. it is either due to pump or fuel rail or fuel lines. you'd have to test pressure before and after removal of the fuel rail to know if the fuel rail is hindering fuel delivery.
Hmmm....I put the AEM fuel rail back on and its working fine now. But then again, I was switching a lot of my fuel components trying to see what the problem was.
 

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have you dyno'd your car as of late? i guess you dont have to. i just wanted to know if you are running lean at higher rpm. but then, you could just add more fuel with a few keystrokes to your fmu. although you could add more fuel to fix your a/f ratio, your fuel line could still be losing pressure.
id still like to know if you have a drop in fuel pressure at higher rpm. using a fuel pressue gauge is the only of knowing for sure that the current pump is supplying enough pressure to provide adequate amounts of fuel to the engine.
are you using the stock pump? what whp are you putting down?
 
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