I have a 95 mustang with a modded 302. bored, heads, cam. just put a procharger d1sc on it. Took it to the dyno and at about 4800-5000 rpms the left bank starts to lean out. the right side is using all the fuel and there isnt any when it crosses over to the left. I have a 255 intank pump. with 42lb injectors. I got rid of the FMU and had my computer tuned. I thought maybe when i installed the fuel pump i might have kinked the rubber hose. so yesterday i dropped the tank and made sure there was no kinks also replaced the fuel filter thinking that might help, but it didnt... does anyone else have any ideas. Is it possible that my fuel rails are to small, "they are stock rails" and i cant get enough volume. Im getting plenty of pressure to right side of the rail beacuse thats where my fuel pressure guage is. but no idea whats going on, on the left side of the rail. When i start to get into some boost my fuel pressure jumps to about 52, and slowly climbs 1psi for every pound of boost, just like its suppose to. I only made 291 to the wheels at 4800 rpms so its not a huge amount of power. it was at about 8lbs of boost and im hoping for 12. Come on guys help me out!!!!!
Not getting enough fuel. Need Help
- Thread starter 1fast95stang
- Start date
exactly what is "leaning out" what AFR is targeted at WOT. and what AFR readings are you getting when its leaning out.
well if there is pressure in the fuel rail then that means the whole fuel rail is filled with fuel( or else there couldnt be pressure). so i dont think the left side of the rail is getting staved for fuel.
if the right back was taking all the fuel from the left thats means the fuel system cant keep up and wouldnt create pressure.
since your fuel pressure stays constant through the rpm range and does drop i am sure you have enough fuel.
do you have an ignition box? what plugs/heat range and gap are you running??
ignition breakup at high rpms(or any rpm for that matter) will show lean on a gauge. 02s read oxygen in the air to determine AFR not fuel. if your ignition isnt adequete, your getting unburned fuel going out the exhaust and the un-used air goes along with it and the o2 will pick up the o2 in the exhaust and show lean. this is with a WB. i dontk know if you used a WB or a sniffer in in the tail pipe but i assume they work the same way.
i had a similar problem. my car would run good up to 4500+ and it would start breaking up follow with lean reading on my wideband.
thought it could have been fuel via 190lph pump i was running at the time or my tune which wasnt perfect yet on my tweecer. didnt have a FP gauge at the time on the car.
i was very inclinded towards ignition, i lowered the gap on the plugs to .025 and it helped but didnt cure the problem totally. put on an igntion box and opened the plug gap back up to .035 and the car came alive, doesnt break up and pulls great and my W/B doesnt "lean" out
running ignition on a blown car isnt ideal. the fuel and air mix gets so dense the spark can have a hard time jumping the gap, lowering the gap can help but you lose performance making your spark smaller. only real way to cure it is with an aftermarket ignition.
i was quite suprised at how much difference an ign box made on my car. you could FEEL the difference, car feels more powerful all through the rpm range and even drove around town smoother.
you also mentioned you had your computer tuned. was is a good dyno tune
was it tuned before of after you put on the blower??
what maf meter are you running???
if your car was tuned before the blower you lambses (desired AFR) may be good for N/A and not rich enough for a blower)
you could be pegging your MAF
IMO if your fuel pressure isnt flucutaing i'd say your fuel is good, its either your spark or in the tune.
well if there is pressure in the fuel rail then that means the whole fuel rail is filled with fuel( or else there couldnt be pressure). so i dont think the left side of the rail is getting staved for fuel.
if the right back was taking all the fuel from the left thats means the fuel system cant keep up and wouldnt create pressure.
since your fuel pressure stays constant through the rpm range and does drop i am sure you have enough fuel.
do you have an ignition box? what plugs/heat range and gap are you running??
ignition breakup at high rpms(or any rpm for that matter) will show lean on a gauge. 02s read oxygen in the air to determine AFR not fuel. if your ignition isnt adequete, your getting unburned fuel going out the exhaust and the un-used air goes along with it and the o2 will pick up the o2 in the exhaust and show lean. this is with a WB. i dontk know if you used a WB or a sniffer in in the tail pipe but i assume they work the same way.
i had a similar problem. my car would run good up to 4500+ and it would start breaking up follow with lean reading on my wideband.
thought it could have been fuel via 190lph pump i was running at the time or my tune which wasnt perfect yet on my tweecer. didnt have a FP gauge at the time on the car.
i was very inclinded towards ignition, i lowered the gap on the plugs to .025 and it helped but didnt cure the problem totally. put on an igntion box and opened the plug gap back up to .035 and the car came alive, doesnt break up and pulls great and my W/B doesnt "lean" out
running ignition on a blown car isnt ideal. the fuel and air mix gets so dense the spark can have a hard time jumping the gap, lowering the gap can help but you lose performance making your spark smaller. only real way to cure it is with an aftermarket ignition.
i was quite suprised at how much difference an ign box made on my car. you could FEEL the difference, car feels more powerful all through the rpm range and even drove around town smoother.
you also mentioned you had your computer tuned. was is a good dyno tune
was it tuned before of after you put on the blower??
what maf meter are you running???
if your car was tuned before the blower you lambses (desired AFR) may be good for N/A and not rich enough for a blower)
you could be pegging your MAF
IMO if your fuel pressure isnt flucutaing i'd say your fuel is good, its either your spark or in the tune.
the reason i thought it would be the fuel is the fact. When we did a dyno he hooked up wideband sensors and the left bank would lean out. im not sure of the number that it was putting out. i just saw it on the chart and he explained it to me. The fuel pressure guage is reading right where the fuel is coming in so we figured it wouldnt be able to tell what kind of pressure is at the other side of the fuel rail.
The car was tuned after the blower was put on.
As for plugs i have autolite Iridum gapped at .30 and a MSD distibutor, MSD blaster coil, but no igntion box. Have Accel wires.
The MAF is a PMAS calibrated for my 42lbs
so if i gap the plugs smaller you think i will notice a difference?? and if i do then i should buy an ign box?
The car was tuned after the blower was put on.
As for plugs i have autolite Iridum gapped at .30 and a MSD distibutor, MSD blaster coil, but no igntion box. Have Accel wires.
The MAF is a PMAS calibrated for my 42lbs
so if i gap the plugs smaller you think i will notice a difference?? and if i do then i should buy an ign box?
for there to be a pressure build up near the schraeder valve, the whole fuel rail will have to pressurized with fuel. there is no way to have a pressure on one side of the rail and not the other. if your getting fuel pressure readings via the schraeder valve location i am 99.99999999% sure your fuel rails are filled and pressurized.
as to why one bank is running lean thats very odd and could be alot of things.
do you have a way to datalog the car and view injector pulsewidth on both banks so you can see how they match up? during WOT the EEC goes off the base fuel tables and both banks should be targeting the same AFR. only time you get the two banks targeting AFR is in closed loop where the EEC is recieving feedback from the HEGOS and trimming fuel to stoichiometric according to what the o2s report. during OL the EEC goes off the base OL fuel table which references off load and engine temp.
perhaps your have a gummed up injector not delivering fuel enough to show up lean on the WB.
as for the spark, try lowering the plug gap .010 and run the car again see if you notice a difference. if it helps in a positive way you know its related to ignition. if it doesnt help any at all. then the ignition is fine. but a good ign box is still a good idea. so you can open the plug gap up and get a bigger spark and make more power.
does the car just lean out some and run smooth still or does it actually break up and act like its missing?
i have a problem every now and then with my car where one sides o2 wont heat up, the other will and the car will go into CL. then the EEC starts pulling fuel out on one side and adding fuel to the other. the result is half the motor runnning rich and the other have running super lean. the car will idle and drive pretty bad during this period, once the o2 in question gets heated up and stops lying to the EEC the car smooths up and run perfect.
what i am getting it my engine runs really funny and crappy when the motor runs half rich and half lean, and thats at idle speed and light cruising. i can imagine is would even run worse under WOT load. ( which i couldnt do since the car would go into OL under enough load or WOT) the eec completely ignores the o2s then and targets the base OL table AFRs
Metalcop
Active Member
I would recommend an additional in-line fuel pump. A Vortech T-Rex or an Anderson Ford Motorsport Big Pump should do the trick, nicely. the Anderson Big Pump, for example, with a 255 lph in tank pump will support 50 lb injectors. I would guess that with the 255 in tank and 42 lb injectors, you simply do not have enough pump to support the injectors. The stock fuel rails/lines should be fine, they are good to over 60 gallons of fuel an hour! (if driven properly)
There are formulas out there that tell you what you need for injectors, fuel pumps etc. to get your desired HP number. I believe you will find that you are falling short in the pump area.
There are formulas out there that tell you what you need for injectors, fuel pumps etc. to get your desired HP number. I believe you will find that you are falling short in the pump area.
90_Red_LX
Member
Agreeing with foxfan. There is no possible way to build pressure inside of something if it has more space to use before it is completely filled. Basic physics. Very interesting explanations from him though, I think I learned something today. 
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