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.

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.

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....!!!!!!

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.

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.

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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.

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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.

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.

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?

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Originally posted by ken inn:
it's because of your stock regulator. now you know why i keep harping on adjustable fuel pressure regulator,

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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

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Originally posted by Ant:

quote:

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Originally posted by ken inn:
it's because of your stock regulator. now you know why i keep harping on adjustable fuel pressure regulator,

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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

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

[/QUOTE]ok, whatever you are saying has gone well over my head. please explain. [/QB][/QUOTE]

Let me clear it up a bit.
Someone mentioned that their fuel pressure was fluctuating a bit and you said it was due to the stock FPR and that with an aftermarket FPR the fuel pressure would be much more stable.

My situation is the following
A rewired Walbro 255lph pump with a B&M Commandflow FPR. With the hose off my FPR I attempt to set the base pressure to 50psi however the needle on my fuel pressure gauge still fluctuates approximately +/- 1psi. However when I put the vaccum line back on the FPR the fuel pressure gauges fluctuates much more to a degree of +/- 4psi.

This should not be the case according to your statement about the FPR stablizing the fuel pressure. I am now thinking that due to the B&M utilzing the stock diagphram from the stock FPR that may be the reason why it is fluctuating. I had a SpoolinUp Unit on my car for a short period of time and I do not recall the fluctuations on the fuel pressure gauges.

So basically I think I just answered myself but add your comments if you like.

Ant

The B&M unit that modifies the stock FPR is only able to *raise* the base fuel pressure not lower it.

i.e., the B&M unit is worthless if you have an upgraded pump.

Mark Rieb