smg944

iTrader: (34)

well went out to go do some more tuning and even out the mid rpms. when i started my full out pulls i was hitting 100% fuel at 14psi and getting between 11.0-11.3 afr's by 7k rpms. i have a supra pump. i cant see why my inj duty is so high. fuel pressure was ok. any ideas on wtf is causing this?

NeedFD

. damn i just read your sig and your setup.. can't make sense out of it..

smg944

iTrader: (34)

cant figure it out either, i have a supra pump also. i look at this thread along with others and wonder what is wrong with my setup. here is an fd making 380whp with 4 850's, i have much more fuel then that. something doesnt add up.

https://www.rx7club.com/showthread.p...x6+turbo+specs

cewrx7r1

iTrader: (2)

OK fuel pressure; is that at idle, 0 boost or on boost?
What is your 0 and 14psi boost fuel pressures?


Clogged fuel filter or line.
Crimped hose or line.
Low voltage to pump.
Improperly setup fuel system.
Improperly setup PFC injectors settings.
Secondary injectors not working.
Fuel pump connector in tank leaking. My plastic/metal connector broke on mine. Replaced with double clamped hose that can't leak.

smg944

iTrader: (34)

i have 42 psi at 0 and then it rises with boost after that. now that i think about it i have had this problem for a while. chuck, i am going to go through that whole list and see what i come up with. thanks

btw the problem i was having with my old setup, 335whp at 13psi with 550/1200's and hitting 90% inj duty.

only thing that comes to mind that could be wrong is that my 550's have 80k miles on them....

AZ'sFastFD3S

Rewire the PUMP. Thats the problem, I promise. I have two supra pumps wired to 14 volts. no fuel probs anymore.

Node

iTrader: (1)

yeah, supra pumps are way voltage dependent

chris roth blew his motor due to a alternator not sending out full voltage and supra pump did not like that

smg944

iTrader: (34)

what about getting a apexi bnr skyline pump? i have heard good news about those, or should i just go ahead and wire it up.

dubulup

re-wire

fastcarfreak

he already said his fuel pressure is not the problem, that should rule out the pump.

This is wierd indeed... I think your overlooking something on your setup.

crazyrx7

I think that your primary injectors are probably failing on you. You said that they have 80k miles on them. I replaced my primaries with newly rebuilt and cleaned ones and I don't have a problem. BTW how is the car running compared to your old maps?

R.K.

smg944

iTrader: (34)

rad, the car is running pretty good, the mid section has evened out. still need to get it on the dyno though. i want to fix this fuel problem though. your running stock wiring correct? if you wouldnt mind could you take a volt reading off yours. this way i can see how low/high my voltage is. btw what was you inj duty with your 402whp pull?

dubulup

are you watching/logging fuel pressure at WOT at the top of 4th?

crazyrx7

I had to pull out some fuel in the mid section as well. As for the duty cycle I don't recall what it was as I wasn't in the car when the dyno runs were done (the dyno operator has to do the runs due to insurance purposes). How am I supposed to get the voltage at the pump when I am driving the car? The power fc tells me that I have 13.5V while I am driving if that means anything.

R.K.

Turblown

iTrader: (12)

Have you had those 1600cc flow tested? Thats the only time I've seen something like that happen. Just out of curiousity what is your injector duty cycle while cranking or normal driving around town out of boost..

Have you monitored fuel pressure while under full load?

smg944

iTrader: (34)

rad, i was saying the voltage at the pump at idle. i was reading some threads that the resistance in the pump could be to high and cause pressure/voltage drop.

well i wired up the pump, got a bmw relay because i couldnt find a hella, has 13.5 volts at the pump now, prior was 11.9 which wasnt too bad for stock wiring, i noticed a jump of 8 psi on the base pressure, so it definaly helped. i dialed back the pressure to 33 psi at idle. but, it is still running at 11 afr's with the pump wired.

the 1600's were brand new, so i am figuring they are ok. im going with some new primarys i think those are whats causing my problem.

dubulup

I think your FPR is the problem is this is a true statement

smg944

iTrader: (34)

dubulup it is a true statement. before pump re wire it was 32 psi at idle, after pump rewire it was 38-40psi at idle. these measurements were read by my defi fuel guage not the guage on fpr. i would figure this would be fine, since fuel pressure is basicly being raised at all times....

also afterwards i did some full boost runs and the fuel pressure seemed pretty steady at 48-49 psi with the boost set at 8-9 psi. one thing i noticed was that i now set my idle fuel pressure at 33-34 psi and even with it raised like that at 0 boost it was reading only 40 psi still. i would figures with the 2 psi added to the idle, it would go up all around. ( as in 42 psi at 0 and 50-51 psi at 9 psi boost. )

smg944

iTrader: (34)

btw here is the fpr i am using, its the sard unit.

http://www.rx7store.net/category_s/92.htm

crispeed

I know a couple of people having problems with that particular regulator and it was all related to the rise in fuel pressure under boost.
You should check your fuel pressure at the boost level your injectors were maxing out under full load like in 4th gear.

smg944

iTrader: (34)

crispeed, will do several pulls and see what the outcome is. fwiw, i think this has been an ongoing problem, even before the sard fpr or the 1600's. when i had my 550/1200 setup i maxed those out by 335 whp with 91% inj duty. that was already odd. i think its either my 550's or something is up with the fuel pump. i just rewired it and it made almost no difference in the top end fuel.... is it even possible to be my 550 injectors? even if they were only pushing out 350cc per injector it still shouldnt be that bad but, they do have 80k miles on them.

smg944

iTrader: (34)

did some looking in my fuel pump. this plasic was cracked. it goes at the very top of the fuel pump. here is a pic. i am figuring this is what was causing the problem. what do you guys think? btw, thanks chuck on reminding me about this in the fuel pump.

smg944

iTrader: (34)

btw just to make sure, which way and in what order does this plasic piece, the rubber o-ring, and the snap plastic go? the service manual doesnt show it.

crazyrx7

I had the same thing happen to me. I ordered that exact piece with the new "o" ring that goes on the pump. I went to install it and realized that the plastic part that you have a picture of will not fit on top of the mkiv supra drop in pump that I have. All I did was replace the "o" ring and left out that plastic piece. I have had no problems since.

R.K.

cewrx7r1

iTrader: (2)

Yup, mine cracked a few years back. I cut off the unit from the metal tube, and replaced it all with a douple clamped hose from the tube directly to the FP outlet nipple.