Wacky Fuel pressure

04DrBlur · May 24, 2003

I just installed my fuel pressure gauge and the damn thing wont sit still. It constantly fluctuates between 40-45 psi. We also hooked the same gauge up on my buddies GSX and it holds steady. He has a 190 lph pump and I have a 255 walbro. Is this due to air in my line? or because I am still running the stock regulator?

ken inn · May 24, 2003

it's because of your stock regulator. now you know why i keep harping on adjustable fuel pressure regulator, especially for high output fuel pumps. the walbro is not only high output, but also hi pressure. you cannot tune the car properly, because your fuel pressure is all over the place.

04DrBlur · May 24, 2003

Ken I realize you said get a regulator so I listened and ordered one on Feb. 25 and still havent got it. Damn that Chargedair.fuckincom. Also I have the 255 low pressure pump if it makes any difference. Thanks for the info. Is it goin to affect my car on the track? Headin there in the morning...

ken inn · May 24, 2003

the best way to see is with a logger. the car can run just as bad rich as lean. there are so many variables, like octane and boost, to name a couple, you need to control as much as you can to make the tuning consistent. that charged air sure sounds like a lousy company. i was lucky to get my afpr from spoolinup, and it only took a week. i think my chinese accent scared them.

4orced4door · May 24, 2003

I agree about needing a regulator. I am going to order one this week. I have been running a walbro 255HP with the stock reg, and it's running extremely rich. Losing power, killing my gas mileage... I wouldn't recommend a 255 to anyone not wanting to get an AFPR!

Turbo4door1 · May 25, 2003

At WOT, the stock regulator is fine. For normal day to day drivng, having the stock regulator makes it nearly impossible to tune completely with a high pressure/high volume pump. (I'm running the Denso TT-Supra pump, so I am definitely having this problem.) Marty G. still uses the stock regulator (which surprised me when I saw his car at our Northern VA GVR-4 get together). He not only drags the car, but frequently road races it and dynoed over 400HP at the wheels - closer to 450 if I recall correctly. Probably runs very rich at idle and part throttle. but under boost, he says it is more than sufficient. I as well ordered an AFPR from ChargedAir, but got tired of waiting and not getting a response to my emails and phone calls, so I just reversed billed it through my credit card. I heard that Ramchargers is getting ready to make a bolt on one for DSMs, but I'm not sure I want to wait any longer. Looks like Buschur will be recieving a phone call for one of his modified Aeromotive units. Should have went that route in the first place, and not tried to save a few bucks....!!!!!!

May 25, 2003

hai guys...currently i have change my fuel pump to nissan skyline pump...but don't know which model...because i need bigger pump...but i think it is not the skyline rb26det pump...previously i'm using my standard 4g63NA pump...and not enough fuel....well my problem are...after changing the pump my idle has problem...at idle my car idle not smooth anymore....like not enough fuel/ruiing to rich...and computer box tried tried fix it...that why my idle is suffer....i'm still running stock fuel regulator....can rewiring fuel pump solve this problem...

Arty · May 25, 2003

The orifice inside the stock FPR is only 2mm diameter. It can't flow enough fuel to regulate the flow from a larger fuel pump.
That's a 2mm drill bit sticking out of the orifice.

Hertz · May 27, 2003

quote:Originally posted by bujang_hensem:
hai guys...currently i have change my fuel pump to nissan skyline pump...but don't know which model...because i need bigger pump...but i think it is not the skyline rb26det pump...previously i'm using my standard 4g63NA pump...and not enough fuel....well my problem are...after changing the pump my idle has problem...at idle my car idle not smooth anymore....like not enough fuel/ruiing to rich...and computer box tried tried fix it...that why my idle is suffer....i'm still running stock fuel regulator....can rewiring fuel pump solve this problem... Rewiring ensures that a consistent voltage reaches your pump. This is more of a "fix" for higher-rpm problems, whereas a new adjustable fuel pressure regulator is more of a "fix" for lower-rpm/idle problems.

You should do both.

04DrBlur · May 27, 2003

Since I am in a pinch and need a FPR I want to go get the B&M commandflo until my chargedair unit comes(if it ever will...). I need to know how big to drill out the orifice in the stock regulator. I have a spare and am goin to drill it out and get it ready so I can just bolt it up.

Arty · May 27, 2003

The orifice is a hardened insert. Myself, and others before me, have tried drilling it, but the drills won't cut it.

4orced4door · May 27, 2003

quote:Originally posted by 04DrBlur:
Since I am in a pinch and need a FPR I want to go get the B&M commandflo until my chargedair unit comes(if it ever will...). I need to know how big to drill out the orifice in the stock regulator. I have a spare and am goin to drill it out and get it ready so I can just bolt it up. Just in case you didn't know, you can't lower pressure with the B&M unit, so if you are trying to rectify a rich condition it's not going to help you. My brother has one.

04DrBlur · May 27, 2003

I have a full machine shop where I work. And a good friend whom works for a steel factory. I can assure you that I can drill it out. Just need to know how big I should make it.
If I had the whole drilled out why would the B&M not lower fuel pressure when it claims it is adjustable from 25 psi- 60psi?

ken inn · May 27, 2003

when i did my fuel pump, i installed the 3kgt vr4 pump, and WITH NO OTHER CHANGES, my jumptronix went from .91 clear to .99. even after a couple of weeks, it never came down much, i was still getting .94-.96 wot. after i got the spoolinup afpr, i adjusted it to 36 psi static, 27 at idle with the vacuum attached. then, i rewired the pump, idle jumped to 29, and i had to retune the afc for low throttle. i am convinced that the adjustable fpr enables a much finer tuning, no matter what pump you have. even stock.

Arty · May 27, 2003

When you are successful at drilling it out, I'd really appreciate the details on how do it.

I was thinking that I could grind it out but I'd need a 3mm diameter grinding tool of some sort ?
I don't know, maybe there's some kind of diamond encrusted tool as small as 2mm, that you can pick up or borrow, for less than a AFPR ?

May 27, 2003

so far with my new fuel pump , 14b with boost level 15psi.450cc...my car still running rich (with autometer A/F meter)...is it normal..at 180kmh also still running rich...is it normal?

May 28, 2003

quote:Originally posted by 04DrBlur:
I have a full machine shop where I work. And a good friend whom works for a steel factory. I can assure you that I can drill it out. Just need to know how big I should make it.
If I had the whole drilled out why would the B&M not lower fuel pressure when it claims it is adjustable from 25 psi- 60psi? That would be fantastic if you could figure a way to drill that orifice out. I've tried several times to drill out my GVR-4 or 3000GT regulators, but did nothing but break off drill bit after drill bit. As far as the size, let me give you one point of measure: the AEM regulator comes with 3 different orifices, .100, .150, and .200. The stock orifice is

May 28, 2003

quote:Originally posted by ken inn:
it's because of your stock regulator. now you know why i keep harping on adjustable fuel pressure regulator, I have a rewired walbro 255 with a B&M FPR and the gauge still bounces around from 46-50psi with the hose on.
With the hose off I can set it to 50psi and it only bounces about +/- 1psi

Ant

May 28, 2003

Another option I know someone on here mentioned before is the AEM fuel rail and universal fuel pressure regulator. It looks like, with some smart Web shopping, you can get the pair for justa little over $300, if you can get past all the Toonerzzz who stock Honduh-only stuff

With the selectable orifices, it should be a nice system.

ken inn · May 28, 2003

quote:Originally posted by Ant:
quote:Originally posted by ken inn:
it's because of your stock regulator. now you know why i keep harping on adjustable fuel pressure regulator, I have a rewired walbro 255 with a B&M FPR and the gauge still bounces around from 46-50psi with the hose on.
With the hose off I can set it to 50psi and it only bounces about +/- 1psi

Ant ok, whatever you are saying has gone well over my head. please explain.

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Wacky Fuel pressure

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