HELP, Running really lean!
Mar 22, 2006, 12:02 PM
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HELP, Running really lean!
So Ive had the RRM stage 1 set-up on my car for awhile, and decided to see how much power she's got this morning. To my surprise, the lancer ran EXTREMLY lean and the guys at shop said that there was not enough fuel getting to the motor and wouldnt not even pull it for a 3rd time. Im not making nearly as much power as i should. Im begining to think there is something wrong with the FMU but im not sure. What do you guys think? They also suggested me getting a fuel pressure gauge to monitor the fmu. The car runs fine, which is weird. I Would have never known there was a problem if I didnt get it dyno'd. It feels faster than stock but it should be alot faster according the this dyno sheet.
Mar 22, 2006, 12:44 PM
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I also think it is the FMU. You can try some injector cleaner (fairly cheap) to see if your injectors are clogged. Other than that I would think it would be your FMU or fuel pump. I heard a lot of guys say that there fuel pump went out.
Here's a question for people that might know:
How long are walbro 255lph suppose to last because it seems like they don't.
Here's a question for people that might know:
How long are walbro 255lph suppose to last because it seems like they don't.
Mar 22, 2006, 12:53 PM
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Let me just be the first to tell you that if your fuel pump goes out.... your ride don't start. So it's definitely not the fuel pump. What is a FMU? Fuel Measuring Unit? Fuel Metering Unit? Frozen Mocah Unit?
Mar 22, 2006, 12:55 PM
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FMU - Fuel Management Unit. It increases fuel pressure has intake pressure goes up.
12:1 FMU will increase the fuel pressure by 12 psi for every 1 psi of positive pressure in the intake manifold.
12:1 FMU will increase the fuel pressure by 12 psi for every 1 psi of positive pressure in the intake manifold.
Last edited by blaze_125; Mar 22, 2006 at 12:59 PM.
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Mar 22, 2006, 12:58 PM
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Fuel Managment unit. It's def not the fuel pump because I can hear it doing something. its really loud. I dont know how it could be the injectors because their stock and I only have 30kmiles on my car. How would they get clogged? Is it possible I have a leak somewhere? I really dont know.
Mar 22, 2006, 02:26 PM
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sounds like fuel pump or fmu...
Fuel pump could still be whinning but not pumping good pressure. Best way to tell is to test the fmu by plugging the line going to it and then hooking up a line to it that you can pressurize to like 5 psi at idle. After you do this you should see fuel pressure go up considerably. If it goes up the fmu is working... if it only goes up to 70-80psi then the pump is gone.
Fuel pump could still be whinning but not pumping good pressure. Best way to tell is to test the fmu by plugging the line going to it and then hooking up a line to it that you can pressurize to like 5 psi at idle. After you do this you should see fuel pressure go up considerably. If it goes up the fmu is working... if it only goes up to 70-80psi then the pump is gone.
Mar 22, 2006, 02:40 PM
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After looking at the dyno i'd say it was fuel pump... see how it gets richer after boost onset? It's still way lean but it does richen up and stays on a very good line. So the FMU is keeping the pressure consistant with the boost and raising it up when boost hits. However your lean since the pressure isn't as high as it should be.
Replace the fuel pump... you should be set then.
Replace the fuel pump... you should be set then.
Mar 22, 2006, 02:46 PM
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Do we have some kind of fuel regulator (return fuel system)? Do you guys think if I get an emanage with 440 injectors, my problem with dissapear? If there was something wrong with my fuel pump, my car wouldnt be running..
Mar 22, 2006, 03:17 PM
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Ok, So Im going to buying a new walbro 255 fuel pump, greddy emanage and new injectors. I hope this solves the lean issue... **** the FMU. Im going to do things right with the emanage. So why do you guys think I Got such shi**y numbers? A leak? where? How do i find it?
-tyler
ps if the motor's ****ed which could be the reason that I wont be making any more power after I buy the parts above, I Will be so pissed.
-tyler
ps if the motor's ****ed which could be the reason that I wont be making any more power after I buy the parts above, I Will be so pissed.
Last edited by Melaz425; Mar 22, 2006 at 03:19 PM.
Mar 22, 2006, 04:19 PM
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Dude i think u need to chill!!! Sounds to me like u should dump a new pump in and see what happens.
PS. U asked how injectors get dirty?! Strain a gallon of gas and see how much crap gets caught. LOL
PS. U asked how injectors get dirty?! Strain a gallon of gas and see how much crap gets caught. LOL