fuel delivery prob.

vortech4.6l · June 30th, 2008, 10:42 AM

okay im not getting barely any fuel at high rpms.... i thought it was because my fmu wasnt hooked up. but i hooked it up and im still not getting more then 38lbs of fuel with 9psi boost. im blowing carbon smoke out the pipes at high rpms too. it runs smooth untill i get about 4500 rpms. do you think it could be a clogged fuel filter or something worse.

ModMustang97GT · June 30th, 2008, 04:14 PM

Carbon out the back means your running rich. Light smoke means lean. At high rpm your fuel pressure will drop due to higher manifold pressure. Do you have an upgraded pump or boost-a-pump? All those things contribute.

vortech4.6l · June 30th, 2008, 07:42 PM

well my vortech external pump went out today when i was changing the filter. so now im only running 25psi fuel. okay so black means rich my plugs are redish though...

ModMustang97GT · July 1st, 2008, 01:31 PM

Redish? I've never seen that. You have got to be burning some sort of additive. Generally its white or black. I have seen a small brown color. I believe the plug was running hot. What does the electrode look like? Coroded, dotted, dark, clean?

vortech4.6l · July 1st, 2008, 05:04 PM

dark, well ive been messing around with it all day, the pump works okay but im only reading about 32 max fuel psi, but when i rev up the engine the fuel gauge drops to like 5to8psi. im not knowing much about this whole thing but do you think its my regulator?

vortech4.6l · July 3rd, 2008, 07:41 AM

i dunno what to do guys, ive tested both the vortech trex pump and the stock pump they both work, the only other think i can think of is my fmu but i dont know how to test it...please any help or experiancce would greatly be apprieciated.

Blower Head · July 3rd, 2008, 08:34 AM

The function of the FMU is to slow the flow of fuel back to the tank under boost and thus increase fuel pressure. If you can unplug the vacuum line from the FMU with the car running and apply a small amount of air pressure (5-10 PSI) to the port you should see your fuel pressure increase. If that does not happen I would suspect the FMU has a leak. I have a new one I didn't use on my Mustang if you discover yours is bad I would be willing to sell. Otherwise maybe it is time to consider a tune with 42# injectors and a 90 mm maf as I am running and get rid of that FMU!

vortech4.6l · July 4th, 2008, 07:45 AM

well i just baught this car from my dad and when i took it to the shop to get it looked at he told me why i wasnt using my fmu because it wasnt plugged in, so i plugged it in and now it feels like my car is missing at about 4500rpms and on/. do you think he he wasnt running the fmu on purpose?

97S281 · July 11th, 2008, 10:04 PM

He's your dad dude, why don't you call and ask him? While you still can.

June 30th, 2008, 10:42 AM	#1
vortech4.6l Regular 1998 GT Join Date: Apr 2008 Location: Ft. BraGG Posts: 118 iTrader: 0 reviews	fuel delivery prob. okay im not getting barely any fuel at high rpms.... i thought it was because my fmu wasnt hooked up. but i hooked it up and im still not getting more then 38lbs of fuel with 9psi boost. im blowing carbon smoke out the pipes at high rpms too. it runs smooth untill i get about 4500 rpms. do you think it could be a clogged fuel filter or something worse.

July 1st, 2008, 01:31 PM	#4
ModMustang97GT Hardcore Enthusiast 1997 Mustang GT Faster than an s4 Join Date: Aug 2007 Location: Seattle, WA Posts: 1,598 iTrader: 0 reviews	Redish? I've never seen that. You have got to be burning some sort of additive. Generally its white or black. I have seen a small brown color. I believe the plug was running hot. What does the electrode look like? Coroded, dotted, dark, clean? __________________ Aztec Gold 97GT. MM CC Plates, Panhard Bar, SFC's & Tower Brace Eibach Sway Bars H&R Race Springs/Bilstein Shocks MAC CAI, LT's, Catted H and Pro-Dumps KB Boost-a-Spark 04' PI Motor Author of The Official Suspension Guide

July 3rd, 2008, 08:34 AM	#7
Blower Head Regular 1996 Mustang GT Vert Join Date: Oct 2007 Location: blaine, MN Posts: 270 iTrader: 1 reviews	The function of the FMU is to slow the flow of fuel back to the tank under boost and thus increase fuel pressure. If you can unplug the vacuum line from the FMU with the car running and apply a small amount of air pressure (5-10 PSI) to the port you should see your fuel pressure increase. If that does not happen I would suspect the FMU has a leak. I have a new one I didn't use on my Mustang if you discover yours is bad I would be willing to sell. Otherwise maybe it is time to consider a tune with 42# injectors and a 90 mm maf as I am running and get rid of that FMU! __________________ 96 GT vert, Aftercooled Vortech, Lightning MAF,42# injectors, saleen cams, Bullitt intake, tune by Hitech, Magnaflow catback and O/R xpipe, Cobra brake upgrade, lowered bilstein suspension w/MM c/c plates and subframe connectors 3000 stall and 3.73's

July 11th, 2008, 10:04 PM	#9
97S281 Rollin' 18/ pushin' 2 1997 Saleen S281 Join Date: Feb 2007 Location: The lost highway Posts: 6,673 iTrader: 13 reviews	He's your dad dude, why don't you call and ask him? While you still can. __________________ MODS IN GARAGE NCMM ORIGINAL BLOWN 96-98 CREW MEMBER # 1

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June 30th, 2008, 04:14 PM	#2
ModMustang97GT Hardcore Enthusiast 1997 Mustang GT Faster than an s4 Join Date: Aug 2007 Location: Seattle, WA Posts: 1,598 iTrader: 0 reviews	Carbon out the back means your running rich. Light smoke means lean. At high rpm your fuel pressure will drop due to higher manifold pressure. Do you have an upgraded pump or boost-a-pump? All those things contribute.

June 30th, 2008, 07:42 PM	#3
vortech4.6l Regular 1998 GT Join Date: Apr 2008 Location: Ft. BraGG Posts: 118 iTrader: 0 reviews	well my vortech external pump went out today when i was changing the filter. so now im only running 25psi fuel. okay so black means rich my plugs are redish though...

July 1st, 2008, 05:04 PM	#5
vortech4.6l Regular 1998 GT Join Date: Apr 2008 Location: Ft. BraGG Posts: 118 iTrader: 0 reviews	dark, well ive been messing around with it all day, the pump works okay but im only reading about 32 max fuel psi, but when i rev up the engine the fuel gauge drops to like 5to8psi. im not knowing much about this whole thing but do you think its my regulator?

July 3rd, 2008, 07:41 AM	#6
vortech4.6l Regular 1998 GT Join Date: Apr 2008 Location: Ft. BraGG Posts: 118 iTrader: 0 reviews	i dunno what to do guys, ive tested both the vortech trex pump and the stock pump they both work, the only other think i can think of is my fmu but i dont know how to test it...please any help or experiancce would greatly be apprieciated.

July 4th, 2008, 07:45 AM	#8
vortech4.6l Regular 1998 GT Join Date: Apr 2008 Location: Ft. BraGG Posts: 118 iTrader: 0 reviews	well i just baught this car from my dad and when i took it to the shop to get it looked at he told me why i wasnt using my fmu because it wasnt plugged in, so i plugged it in and now it feels like my car is missing at about 4500rpms and on/. do you think he he wasnt running the fmu on purpose?

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