Bad fuel pump or FPR?

[KiLLeR2001]

SR20DET Redtop, Walbro 255 fuel pump, stock FPR. Z32 fuel filter (replaced a few months ago). T25 stock boost.

Was driving home tonight from work and decided to get on the throttle a little bit. After reaching 4-5k range the car started to misfire, so I backed off and drove easy all the way home. Car drives perfectly normal until you enter the higher range RPMs.

So I got home and popped the hood and checked my fuel pressure. It was 32psi. I know this is pretty low since stock fuel pressure at idle should be 37.5psi. The FPR has its own vacuum source, nothing T'd off or anything. When disconnecting the FPR vacuum and the engine running at idle... my fuel gauge shows 46psi!

After seeing that the car was idling with 32psi of fuel pressure. I shut the car off, I went out to the garage 10 minutes later and was just checking everything out, then I noticed that my fuel pressure was now in the 40's range (so it went up!). With the engine off, if I prime the fuel pump the fuel pressure is around 43.5psi.

The Walbro fuel pump is around a year old, and after driving for 10 minutes or so, it starts to get noticeably louder in its whining sound.

I'm starting to think I need a new fuel pump AND FPR... LOL

[ultimateirving]

fuel pressure sounds about right, should be about 36psi, with vac, and over 40psi with it unattached. the car will prime at higher psi. In my s13 i know the walbros get angry if you run then hard below 1/4 tank of gas because they use the fuel as lube/coolant.

So it is possible your fuel pump is going out, especially if u run the car down to empty before refill.
otherwise

[KiLLeR2001]

I never run it below 1/4th tank, I can assure you that.

edit: Also, car idles with 32psi, that's not alright...

[310westslide]

I have the same problem except my When I hit around 4k rpm it starts to sputter and I have to like give it a little gas for the car to boost.. Not like a back fire but when I give it gas like it holds back and I have to let go of the gas and give it a little

Can that be a bad walbro? I have a nismo fpr

[StryfeS13]

When was the last time you changed your plugs? What are they gapped at? Are you coilpacks old?

Do you have a wideband?

Oh and also I'll buy that clear gauge cover from you tomorrow dude, sorry for not replying to your PM

[slider2828]

10000000% sure the fuel pump is dead and dying... Walboro's suck shit, but its the cheapest out there....

I am willing to bet its whinned before and been louder since first installed... Fuel pump is KIA

[KiLLeR2001]

Originally Posted by StryfeS13

When was the last time you changed your plugs? What are they gapped at? Are you coilpacks old?

Do you have a wideband?

Oh and also I'll buy that clear gauge cover from you tomorrow dude, sorry for not replying to your PM

Plugs changed about 2k miles ago, gapped at 0.035, stock gap 0.036. Coilpacks are fine. The car runs fine, I'm not worried about the ignition system. The fact that my fuel pressure is 32psi and the fuel pump is making a horrible whining sound is leading me to believe it is the fuel pump.

[KiLLeR2001]

Originally Posted by slider2828

I am willing to bet its whinned before and been louder since first installed... Fuel pump is KIA

Bingo. I actually noticed when I first start the car up, the pump is pretty quiet and the fuel pressure is correct. After driving for 10 minutes it starts to get loud, and when I go to check my fuel pressure, its at 32psi.

[310westslide]

Anyone knows what's wrong with my car?
I googled it and everything but nothing at all

[fliprayzin240sx]

Originally Posted by 310westslide

Anyone knows what's wrong with my car?
I googled it and everything but nothing at all

Have you checked your baseline timing? I'd check timing and spark plugs first...

[310westslide]

I havet check the timing but I have check the spark plugs about a month and a half ago n they were fine fine double check when it stops raining..
I was thinking it Coulb b doing that cause its running lean?

[StryfeS13]

Originally Posted by KiLLeR2001

Bingo. I actually noticed when I first start the car up, the pump is pretty quiet and the fuel pressure is correct. After driving for 10 minutes it starts to get loud, and when I go to check my fuel pressure, its at 32psi.

You have an S13 right? Did you only use that little lock washer that walbro supplies to fasten the fuel sock on? I've heard horror stories of them falling off and shortening the life of the pump

[KiLLeR2001]

Originally Posted by StryfeS13

You have an S13 right? Did you only use that little lock washer that walbro supplies to fasten the fuel sock on? I've heard horror stories of them falling off and shortening the life of the pump

Actually, I was concerned about this very issue a few months back because I DIDNT use the lock washer. So I took out my fuel pump and the sock was still on there securely, so I was relieved. When I take out the pump this time I'll see if it happened to fall off, I'll be putting the lock washer on this time though lol.

[slider2828]

It doesn't matter... walboro's break all the time... Running the pump too low or drifting would cause this thing to die.... I've gone through 3 of these pump's in the last 2.5 years mainly cause of track driving... Its just very sensitive to overheating that is all...

[KiLLeR2001]

Yeah this is the second one I've gone through myself personally... (in 5 years though). Slider would you recommend the Z32 fuel pump as a better alternative?

[slider2828]

Originally Posted by KiLLeR2001

Yeah this is the second one I've gone through myself personally... (in 5 years though). Slider would you recommend the Z32 fuel pump as a better alternative?

I dun think the Z32 is 255LPH.... I think the closest one is the R32 one which happens to be denso of course....

There really isn't a good alternative other than denso or tomei which is close to $300 bux.... That is probably the best that can be done....

I know Deatschwerks came out with a fuel pump, but dunno how good they are.

[KiLLeR2001]

Hmm. According to FRSport.com the Z32 TT pump is 260 L/HR. And reading elsewhere online its the highest flowing OEM Nissan fuel pump available (other than maybe the newer Z's and GT-R).

Nissan OEM 300ZX TT Twin Turbo Z32 Fuel Pump

I think if another Walbro takes a dump for me I'll switch to the Z32 pump.

[swayray]

Its wouldnt hurt to check your maf and the plug since it coukd affecg the sputtering too. And all vacuum lines or intercooler clamps that would show signs of a boost leak.

Just wanna throw that out there just to check that off your diagnosis list

[KiLLeR2001]

Originally Posted by swayray

Its wouldnt hurt to check your maf and the plug since it coukd affecg the sputtering too. And all vacuum lines or intercooler clamps that would show signs of a boost leak.

Just wanna throw that out there just to check that off your diagnosis list

Those were amongst the first things I checked after getting home. When I saw the fuel gauge at 32psi I already had a feeling in my head the fuel pump was toast just because how loud and annoying it gets after 10 minutes of normal driving. A friend of mine also has a Walbro in his s13 and its not even close in the audible level that mine reaches. You can literally walk like 20 ft away and still hear mine...

[slider2828]

Your right its 260 lph, but not direct drop in and might be a little short. For 300 bux, denso is there...

DENSO Fuel Pump Upgrade 260LPH

[KiLLeR2001]

Sounds good, thanks Slider. I'm going to try Walbro one last time, if this next pump isn't anything short of spectacular I'm never buying a Walbro product again.