SR20 fuel issue? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

jing · 11-30-2009, 12:34 PM

Replaced my stock fuel pump recently with a Walbro 255lph fuel pump (donno why previous owner didn't upgrade when he got the SR in). Been driving fine.. until today.

It'll bog intermittently under acceleration and die sometimes at idle when I come to a stop.

I'm guessing either my stock FPR is doesn't like the new fuel pump or my fuel filter is clogged (even though it was replaced 5 months ago).

I'll be buying a fuel pressure gauge and testing that soon.

Any other suggestions?

Specs:
Redtop SR
Stock T25
Turbo outlet + DP
Splitfire coilpacks (don't ask)
FMIC
Atmospheric BOV

brian3676 · 11-30-2009, 12:50 PM

Check MAF and intercooler for leaks

astrophixvox · 11-30-2009, 12:50 PM

def check your pressure. Stock fpr usually don't agree w the walbro. Make sure your fuel pump is getting the right voltage. You'd be surprised w some of these older cars and their old wiring. I also agree w brian above.

JRwerks · 11-30-2009, 08:07 PM

what kind of bov do u have

robertftw · 11-30-2009, 08:31 PM

Do you smell Fuel when stopped or driving?

Along with what others have said check these.
Your fuel pressure should be around 41 psi now with the walbro and stock fpr if it is working correctly and should be turned back down to 36 psi, I have seen a bad run on walbro's lately where they had very low pressure brand new so check the pressure.

The blow off valve going into the atmosphere will cause you to run extra rich if you don't recirculate it on a maf based system, I think AFC's have some sort of way of correcting This but I am not familiar with AFC's.

jing · 11-30-2009, 08:41 PM

BOV is a 2nd gen HKS SSQV

I did smell fuel before when stopped and driving but I assumed that was due to the fuel vapors from taking the pump out getting into the cabin and didn't really go away until I replaced the fuel tank o-ring. The smell's pretty much all gone now.

I checked the MAF out and wiggled it around and unplugged it and it made a pretty big difference as to how the engine ran which would suggest that it's still good. However, when driving it around and I'm in gear and I pop it in neutral, the revs drop down like normal to 800rpm but then they would jump back up and hover around 1500rpm and won't come back down to 800rpm until I come to a dead stop.

I have also noticed that on a cold start, typically my revs will shoot up to 2000rpm and quickly come down to 1500rpm and slowly come down to the normal idle speed of 800rpm after it's warmed up. However, since yesterday, I notice that the revs hover around 2000rpm for longer than usual.

I'm guessing the MAF's still good but that it might be dirty? Who knows.. I'll be buying some carb cleaner tomorrow and using that on the IACV and the MAF sensor... probably also buy a new fuel filter or something too

robertftw · 11-30-2009, 09:05 PM

How long have you been driving since you changed the pump?

check for vacuum leaks and leaks in the intercooler piping.

If the car runs better after messing with the maf check the wiring.

When coming to a stop or shifting to neutral the rpm's dropping below 800 and then coming back up is caused by the open BOV recirculate it and it will go away plus the car won't run as rich afterwards, or if you like the sound look into and see if the AFC's will fix that problem.

Good luck!

11-30-2009, 12:34 PM	#1
jing Zilvia Member Join Date: Dec 2007 Location: Vancouver, BC Age: 36 Posts: 291 Trader Rating: (4) Feedback Score: 4 reviews	SR20 fuel issue? Replaced my stock fuel pump recently with a Walbro 255lph fuel pump (donno why previous owner didn't upgrade when he got the SR in). Been driving fine.. until today. It'll bog intermittently under acceleration and die sometimes at idle when I come to a stop. I'm guessing either my stock FPR is doesn't like the new fuel pump or my fuel filter is clogged (even though it was replaced 5 months ago). I'll be buying a fuel pressure gauge and testing that soon. Any other suggestions? Specs: Redtop SR Stock T25 Turbo outlet + DP Splitfire coilpacks (don't ask) FMIC Atmospheric BOV

11-30-2009, 12:50 PM	#3
astrophixvox Leaky Injector Join Date: Oct 2007 Location: Pharr, Tx Age: 40 Posts: 87 Trader Rating: (0) Feedback Score: 0 reviews	def check your pressure. Stock fpr usually don't agree w the walbro. Make sure your fuel pump is getting the right voltage. You'd be surprised w some of these older cars and their old wiring. I also agree w brian above. __________________

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11-30-2009, 12:50 PM	#2
brian3676 Zilvia Member Join Date: Oct 2006 Location: portland Age: 37 Posts: 205 Trader Rating: (3) Feedback Score: 3 reviews	Check MAF and intercooler for leaks

11-30-2009, 08:07 PM	#4
JRwerks Zilvia FREAK! Join Date: Mar 2007 Location: SOCAL Posts: 1,200 Trader Rating: (55) Feedback Score: 55 reviews	what kind of bov do u have

11-30-2009, 08:31 PM	#5
robertftw Zilvia Member Join Date: Sep 2006 Location: florida Posts: 148 Trader Rating: (8) Feedback Score: 8 reviews	Do you smell Fuel when stopped or driving? Along with what others have said check these. Your fuel pressure should be around 41 psi now with the walbro and stock fpr if it is working correctly and should be turned back down to 36 psi, I have seen a bad run on walbro's lately where they had very low pressure brand new so check the pressure. The blow off valve going into the atmosphere will cause you to run extra rich if you don't recirculate it on a maf based system, I think AFC's have some sort of way of correcting This but I am not familiar with AFC's.

11-30-2009, 08:41 PM	#6
jing Zilvia Member Join Date: Dec 2007 Location: Vancouver, BC Age: 36 Posts: 291 Trader Rating: (4) Feedback Score: 4 reviews	BOV is a 2nd gen HKS SSQV I did smell fuel before when stopped and driving but I assumed that was due to the fuel vapors from taking the pump out getting into the cabin and didn't really go away until I replaced the fuel tank o-ring. The smell's pretty much all gone now. I checked the MAF out and wiggled it around and unplugged it and it made a pretty big difference as to how the engine ran which would suggest that it's still good. However, when driving it around and I'm in gear and I pop it in neutral, the revs drop down like normal to 800rpm but then they would jump back up and hover around 1500rpm and won't come back down to 800rpm until I come to a dead stop. I have also noticed that on a cold start, typically my revs will shoot up to 2000rpm and quickly come down to 1500rpm and slowly come down to the normal idle speed of 800rpm after it's warmed up. However, since yesterday, I notice that the revs hover around 2000rpm for longer than usual. I'm guessing the MAF's still good but that it might be dirty? Who knows.. I'll be buying some carb cleaner tomorrow and using that on the IACV and the MAF sensor... probably also buy a new fuel filter or something too

11-30-2009, 09:05 PM	#7
robertftw Zilvia Member Join Date: Sep 2006 Location: florida Posts: 148 Trader Rating: (8) Feedback Score: 8 reviews	How long have you been driving since you changed the pump? check for vacuum leaks and leaks in the intercooler piping. If the car runs better after messing with the maf check the wiring. When coming to a stop or shifting to neutral the rpm's dropping below 800 and then coming back up is caused by the open BOV recirculate it and it will go away plus the car won't run as rich afterwards, or if you like the sound look into and see if the AFC's will fix that problem. Good luck!