Holy Crap: FPR @ 40psi

Post by **rico05** » Sat Dec 17, 2005 2:51 pm

So, today was a really chilly Tejas day. I went to start my car, and it died 3 times after about 2 sec of running. Hmmm. Started 4th time, and wouldn't idle, so I gave it some gas. The car ran really crappy, and a HUGE cloud of white (gas) smoke enveloped my car. Well, after careful modulation, rock solid idle showed up, and all was fine. I popped the hood, and took a look at my FPR pressure gauge, and low and behold....40psi! So, that is ~5psi more than it should be. Is it b/c the car was stone cold? Did my FPR finally die? When I put the gauge in in summer, it was reading 36psi, and I noticed it seems to be increasing a little bit ever once in a while. So, thoughts?

Post by **boost_boy** » Sat Dec 17, 2005 3:03 pm

rico05 wrote:So, today was a really chilly Tejas day. I went to start my car, and it died 3 times after about 2 sec of running. Hmmm. Started 4th time, and wouldn't idle, so I gave it some gas. The car ran really crappy, and a HUGE cloud of white (gas) smoke enveloped my car. Well, after careful modulation, rock solid idle showed up, and all was fine. I popped the hood, and took a look at my FPR pressure gauge, and low and behold....40psi! So, that is ~5psi more than it should be. Is it b/c the car was stone cold? Did my FPR finally die? When I put the gauge in in summer, it was reading 36psi, and I noticed it seems to be increasing a little bit ever once in a while. So, thoughts?

You have a NISMO unit correct? If so, I had one die on me and I kept it as a souvenir. It Gave silly fp readings at around 40psi and I have to crank it up to 85psi just to run the car. The thing completely showed it's butt on me on the dyno. Put a stock one back in while the car was still on the rollers and went on to produce 332whp@20psi.

Dee

Post by **float_6969** » Sat Dec 17, 2005 3:27 pm

did the jam nut loosen up on you?

Post by **boost_boy** » Sat Dec 17, 2005 4:21 pm

float_6969 wrote:did the jam nut loosen up on you?

Who me!

Dee

Post by **float_6969** » Sat Dec 17, 2005 4:43 pm

both of you...

Post by **rico05** » Sun Dec 18, 2005 10:23 am

I had a Nismo one, but when I put the gauge in, it read normal, so I ditched it.

Update: Car once again wanted to die in the chilly morning, and once again the gauge read 40psi. I let it warm up, ran great...and when I got back, I checked the gauge and it read a steady 36psi. So, is this normal in the cold?

Post by **r34 gtr** » Sun Dec 18, 2005 11:02 am

im not sure about "normal" fuel pressure for that nismo unit as i dont have one. i can tell you though that i too have this same problem when its cold. i usually have to keep my foot in it for a few seconds before it will idle steadily. ill get the gauge out and check it when i start it up today and let you know what i find.

- tim

Post by **boost_boy** » Sun Dec 18, 2005 11:29 am

If you guys are suspecting fuel to be the problem, then I suggest you fast-wire the 12volt fuel pump wire away from the ecu to a more constant circuit. It's been a while since I've done this with my own stuff, but I plan on doing this with my turbocharged 95 hyundai elantra and with a project S13 that I'm doing for one of our members. But sometimes, those cold start actuators can cause you more problem than just cold start issues.

Dee

Post by **rico05** » Sun Dec 18, 2005 12:59 pm

Care to include a procedure on how to do this Dee?

Post by **boost_boy** » Sun Dec 18, 2005 1:29 pm

rico05 wrote:Care to include a procedure on how to do this Dee?

It's fairly simple, but as for simplicity of scribling color codes to accomodate everyone, it'll have to wait until I wire the S13 that I'm about to drop a CA18DET swap with bigger turbo, better manifold, intercooler, blah-blah-blah. It's a full project that I've been dispatched to handle, so when I 'm done or crosss that area, I'll be sure and scribble down what I did with the re-routing of the fuel pump's power supply.

Dee

Post by **Import Is Life** » Sun Dec 18, 2005 6:18 pm

I hope that everything with my swap is going along smoothly. Well my name is Ryan, and I'm the new kid on the block. I hope to share my experience with the CA soon.

Post by **float_6969** » Mon Dec 19, 2005 4:42 am

Welcome. Great name btw. I'm Ryan as well.

I suspect it maybe something to do with the fuel pump as well. Nissan likes to vary the voltage going to the pump for whatever stupid reason. I've got a Nismo FPR as well, but I'm running SDS and so the fuel pump is on a straight 12v relay, actuated by the ECU. It was 11 deg F when I went to check it yesterday and when I turned the key on, it was dead on 36 psi.

I don't think it's the FPR. It's one of two things. You're either running more fuel pressure than normal (varied voltage to the fuel pump) or the FPR is sticking when it's cold. I can't see any reason it would do that, but it would be easy enough to check. Simply get out a hair dryer/heat gun and heat the FPR up before you turn on the key. If it stops doing it, then something is up with the FPR. If it doesn't, then it's the fuel pump.

My guess is still the fuel pump.

Post by **rico05** » Mon Dec 19, 2005 7:30 am

Well then ol buddy Ryan, wanna give me a how to hard wire the pump? I remember a thread on SXOC about this very thing, now that you refreshed my memory on the varible voltage pump situation. Z32s and S13s have this, so it seems that a lot of UK guys upgrade to Z32 pumps to maintain proper flow.

Post by **biosehnsucht** » Mon Dec 19, 2005 4:26 pm

there's no reason that the fuel pump being overrun should run your fpr beyond its range of operation anyways. maybe if it didn't get enough voltage it might not make the FPR's setting and run you lean, but that would be different..

Post by **float_6969** » Mon Dec 19, 2005 9:18 pm

Simply upgrading to a walbro was overruning my stock FPR. I was running super rich with it, and when I hooked up the pressure gauge I think I was at something crazy like 43lbs.

I don't know the internal programming of the ECU well enough to know if Nissan took advantage of this and bumped the flow of the fuel pump up when the temps get below a certain level.

Post by **top_secret** » Wed Dec 21, 2005 6:09 pm

where did you guys get this variable voltage scheme? I know the Z32 has it, it has multiple wires for it... the S13 just uses a 12 volt relay and a single power wire... I thought I read a while ago that US 240sx's don't have variable voltage... I'm pretty sure they don't, in fact.

Post by **f s t caz** » Wed Dec 21, 2005 6:55 pm

float_6969 wrote:Simply upgrading to a walbro was overruning my stock FPR.

ehh? is this a common problem?

edit: according to search, seems like a hit or miss occurance, but then again, a dying oil pump seems hit or miss on CA's. yay for something else to spend moneys on.
Modified by f s t caz at 12:08 AM 12/22/2005

Post by **float_6969** » Thu Dec 22, 2005 12:57 pm

top_secret wrote:where did you guys get this variable voltage scheme? I know the Z32 has it, it has multiple wires for it... the S13 just uses a 12 volt relay and a single power wire... I thought I read a while ago that US 240sx's don't have variable voltage... I'm pretty sure they don't, in fact.

Completely possible. As I said before, I was simply speculating.

Post by **biosehnsucht** » Fri Dec 23, 2005 12:27 pm

I should have been specific, as I was speaking of "your" within the context of the discussion of rico05's situation, I meant an upgraded fuel pump should not overrun a NISMO or other upgraded FPR.

Post by **top_secret** » Fri Dec 23, 2005 3:00 pm

I run one on the stock fpr and haven't experienced a problem yet.

Post by **biosehnsucht** » Fri Dec 23, 2005 5:27 pm

mine was horriblyrich, its kind of hit or miss of a stock one can handle it.

Holy Crap: FPR @ 40psi

Holy Crap: FPR @ 40psi

Re: Holy Crap: FPR @ 40psi (rico05)

Re: (float_6969)

Re: (r34 gtr)

Re: (rico05)

Re: (boost_boy)

Re: (float_6969)

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