Running lean, walbro pump
05-30-2007, 08:12 AM
#1
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Running lean, walbro pump
Ok I need help on a fuel issue a buddie of mine is having. He just installed a vortec SC in his G35 with the walbro 255, he still has stock injectors and installed utec. Well when he starts the car it runs real lean at idle like 18 and it never richens up never drops to even 16 at WOT. So I was thinking it must be the pump because not enough fuel is going to the engine, so how would you know anyway to increse the pressure maybe the regulator? Anyway to incress flow?
05-30-2007, 09:24 AM
#3
Has anyone tried installing the denso supra tt pumps? They are much stronger than walbro, plus push more fluid for longer periods of time.
My friends 450whp VR4 would starve after a while with the 255, so we installed a OEM supra tt pump and it worked wonders.
In your situation I would check the FMU that comes with the kit.
My friends 450whp VR4 would starve after a while with the 255, so we installed a OEM supra tt pump and it worked wonders.
In your situation I would check the FMU that comes with the kit.
05-30-2007, 10:38 AM
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I don't know how he installed it I am going to be taking it out today and see what was done. Also he said he did not drill those 2 3/8 holes on the bottom plastic housing would this couse the lean condition?
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05-30-2007, 11:06 AM
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Yeah the Aux fuel pump. Also not drilling the holes would result in approx an 80 psi fuel pressure where 52 psi is norm..Do you have a fuel gauge installed.? The SS box applies the voltage to turn the Aux fuel pump on while under boost. The FMU feeds the Aux fuel pump..Under boost the Walbro feeds the Fmu which in turn feeds the Aux fuel pump which then flows to the fuel rails and into the injectors..The walbro on my car will not support the fuel requirement without the FMU/Aux fuel system..
05-30-2007, 11:37 AM
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You may have found out why it's lean..The walbro alone w/o a fuel return is likely not capable of meeting the fuel demand..Nothing to replace the FMU/Aux fuel pump..
05-30-2007, 11:45 AM
#12
OK HERE IS THE DL:
You need to get rid of the FMU and inline fuel pump that vortech provides with their full kit, if you have not done so correctly.
you will need to drill out the stock regulator hole and enlarge it in the fuel pump assembly. the stock regulator restricks flow.
you also need to take out the siphone inlet to the bottom of the fuel assembly, since it restricks fuel getting into the pump
you will need bigger injectors if you are running above the 7psi kit
you will be lean above 6500 rpm if you are running anything above the 7psi kit
to be super safe install a aam stage 1 fuel return. $500 gives you a clear mind.
you will NOT need a fmu and inline fuel setup for anything under the 9 psi vortech setup.
You need to get rid of the FMU and inline fuel pump that vortech provides with their full kit, if you have not done so correctly.
you will need to drill out the stock regulator hole and enlarge it in the fuel pump assembly. the stock regulator restricks flow.
you also need to take out the siphone inlet to the bottom of the fuel assembly, since it restricks fuel getting into the pump
you will need bigger injectors if you are running above the 7psi kit
you will be lean above 6500 rpm if you are running anything above the 7psi kit
to be super safe install a aam stage 1 fuel return. $500 gives you a clear mind.
you will NOT need a fmu and inline fuel setup for anything under the 9 psi vortech setup.
Last edited by MUZZY; 05-30-2007 at 11:47 AM.
05-30-2007, 02:07 PM
#16
ok... i got it figured out.. we didnt drill the FPR and didnt remove the yellow plug and also didnt drill the holes in the bottom of the assembly... this will all be done today... Thanks Mark for posting this up... thanks everyone for their insight!
05-31-2007, 03:03 AM
#17
well after taking care of the fuel assembly i have ran into yet another problem... yesterday from running tooo lean i fried my drivers side cat... i replaced it and was wondering if it is normal for one side of my exhaust to blowing cooler air than the other... the side that i fried is cooler... any suggestions?
05-31-2007, 03:40 AM
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Originally Posted by MUZZY
OK HERE IS THE DL:
You need to get rid of the FMU and inline fuel pump that vortech provides with their full kit, if you have not done so correctly.
you will need to drill out the stock regulator hole and enlarge it in the fuel pump assembly. the stock regulator restricks flow.
you also need to take out the siphone inlet to the bottom of the fuel assembly, since it restricks fuel getting into the pump
you will need bigger injectors if you are running above the 7psi kit
you will be lean above 6500 rpm if you are running anything above the 7psi kit
to be super safe install a aam stage 1 fuel return. $500 gives you a clear mind.
you will NOT need a fmu and inline fuel setup for anything under the 9 psi vortech setup.
You need to get rid of the FMU and inline fuel pump that vortech provides with their full kit, if you have not done so correctly.
you will need to drill out the stock regulator hole and enlarge it in the fuel pump assembly. the stock regulator restricks flow.
you also need to take out the siphone inlet to the bottom of the fuel assembly, since it restricks fuel getting into the pump
you will need bigger injectors if you are running above the 7psi kit
you will be lean above 6500 rpm if you are running anything above the 7psi kit
to be super safe install a aam stage 1 fuel return. $500 gives you a clear mind.
you will NOT need a fmu and inline fuel setup for anything under the 9 psi vortech setup.
06-01-2007, 08:35 AM
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OK after drilling out the stock regulator hole, also did drill the 2 holes on the bottom of the white plastic canister. The car is not running to rich. at idle it gets to 8.2 in drive it drops to 7.0 and when we give it gas at about 10% TPS it gets down to 0 very rich the car starts to backfire and the exhaust never gets hot. blows cool air. Anyone know what we can to about a rich condition now?