4th gen SC Fuel Pump related question
10-11-2002, 06:57 AM
#1
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4th gen SC Fuel Pump related question
Do you really need to have the fuel pump in the tank upgraded for a 3.125 pulley? If so recommendations and why this is needed? The guy said he was told he doesn't need it since Stillen came with one. But I explained to him its just a regulator not the pump that comes from the rear. So anyways, advice would be good guys. Thanks.
10-11-2002, 09:37 AM
#5
See that blue thingie in my sig pic? That's the FMU/auxiliary fuel pump.
If you would like the auxiliary fuel pump to be on all of the time here's the link for the Hobs switch instructions.
http://forums.maxima.org/showthread....highlight=hobs
If you would like the auxiliary fuel pump to be on all of the time here's the link for the Hobs switch instructions.
http://forums.maxima.org/showthread....highlight=hobs
10-11-2002, 09:58 AM
#6
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Posts: n/a
Originally posted by BlackCat
See that blue thingie in my sig pic? That's the FMU/auxiliary fuel pump.
If you would like the auxiliary fuel pump to be on all of the time here's the link for the Hobs switch instructions.
http://forums.maxima.org/showthread....highlight=hobs
See that blue thingie in my sig pic? That's the FMU/auxiliary fuel pump.
If you would like the auxiliary fuel pump to be on all of the time here's the link for the Hobs switch instructions.
http://forums.maxima.org/showthread....highlight=hobs
10-11-2002, 11:25 AM
#8
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Posts: n/a
Originally posted by Chunger
Not true, or why would it be there... think about it.
Not true, or why would it be there... think about it.
The rear pump must flow more fuel to the aux one up front before it can give more fuel as well.
Common sense.
10-11-2002, 11:29 AM
#9
Originally posted by RussMaxManiac
It's a regulator to keep a steedy flow of fuel. That little aux PUMP can not pump more fuel IF the rear main pump doesn't pump anymore than it can.
The rear pump must flow more fuel to the aux one up front before it can give more fuel as well.
Common sense.
It's a regulator to keep a steedy flow of fuel. That little aux PUMP can not pump more fuel IF the rear main pump doesn't pump anymore than it can.
The rear pump must flow more fuel to the aux one up front before it can give more fuel as well.
Common sense.
If you want, here are some instructions for a 4th gen:
http://home.earthlink.net/~msue2/Walbro.htm
10-11-2002, 11:32 AM
#10
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Posts: n/a
Originally posted by Chunger
I'm not gonna argue with you... If you want to spend the money, go ahead... You've already got your answer from more than 1 person who knows something or another about it...
I'm not gonna argue with you... If you want to spend the money, go ahead... You've already got your answer from more than 1 person who knows something or another about it...
That is the way the fuel system works. If you blow your engine thats fine. I just wanted to answer yes or no which Kev answered.
10-11-2002, 12:38 PM
#11
Donating Maxima.org Member
Join Date: Oct 2000
Posts: 1,402
Fuel is not something you want to take chances with expecially on a Boosted car...especially when you're pushing boost to 10 psi levels on stock engine & injectors.
The reason Stillen supplies an auxilliary fuel pump is because the stock pump does not provide enough flow at higher fuel pressures. The stock pump will provide enough fuel to run the injectors at 100% duty cycle given OEM 43.5psi fuel pressure.
V-max (gph) = 240cc/min X 6 inj X 0.015873 = 22.86 gph
If you take a look at the fuel pump flow curve, flow decreases as pressures go up. When you double the fuel pressure, you approximately decrease the fuel flow by half. Therefore our stock pump will only flow 11.43gph at 90psi fuel pressure...BAD BAD BAD!.
Fuel pumps added linearly increase fuel pressures while maintaining the same volume of fuel (P1*V1=P2*V2). We can take both OEM fuel pump & Stillen pump, get their actual fuel curves & do some math, however, as an added margin of safety, get the Walbro 255 lph in tank fuel pump. It will be plenty sufficient for a 3.125" pulley.
The reason Stillen supplies an auxilliary fuel pump is because the stock pump does not provide enough flow at higher fuel pressures. The stock pump will provide enough fuel to run the injectors at 100% duty cycle given OEM 43.5psi fuel pressure.
V-max (gph) = 240cc/min X 6 inj X 0.015873 = 22.86 gph
If you take a look at the fuel pump flow curve, flow decreases as pressures go up. When you double the fuel pressure, you approximately decrease the fuel flow by half. Therefore our stock pump will only flow 11.43gph at 90psi fuel pressure...BAD BAD BAD!.
Fuel pumps added linearly increase fuel pressures while maintaining the same volume of fuel (P1*V1=P2*V2). We can take both OEM fuel pump & Stillen pump, get their actual fuel curves & do some math, however, as an added margin of safety, get the Walbro 255 lph in tank fuel pump. It will be plenty sufficient for a 3.125" pulley.
10-12-2002, 09:20 PM
#12
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I wanted to buy one, just got one off another member
I just bought a Walbro fuel pump from another member. Hope this all works out for me, even though I have the Vortech which I will remove from the car to make a bit more space under my hood. It is crowded up in there, SC and those freaking Ballasts just dont help. So Bobby you replaced your Aux Vortech pump with a intank fuel tank. Smart I think it is. That AUX pump gets warm. I really dont want a warm fuel pump even though it does its job I prefer one that sucks right of the Tank. I have to take Russ idea into a bit of consideration. I am not saying hes right or wrong is the simple fact that the statements seem very factual in my eyes and make sense.
10-12-2002, 10:32 PM
#13
Originally posted by RussMaxManiac
Let me tell you something. I have installed 2 Supercharger kits on Maximas. I know how the fuel system works. I am asking OTHER people if they needed to upgrade yet because how close the stock fuel pump is already maxed out with a SC. That is why LOREN, MARDI-GRA, THENEWCLIMAX, and a few others have a bigger fuel pump.
That is the way the fuel system works. If you blow your engine thats fine. I just wanted to answer yes or no which Kev answered.
Let me tell you something. I have installed 2 Supercharger kits on Maximas. I know how the fuel system works. I am asking OTHER people if they needed to upgrade yet because how close the stock fuel pump is already maxed out with a SC. That is why LOREN, MARDI-GRA, THENEWCLIMAX, and a few others have a bigger fuel pump.
That is the way the fuel system works. If you blow your engine thats fine. I just wanted to answer yes or no which Kev answered.
Loren sold me his SC.
He doesn't have it anymore.
I bought it.
And he never had smaller than a 3.25" Pulley
He said he only ever had the Aux pump.
Unless he bought another SC, but I don't think he did, because he told me what he's been working on, and it's not another SC.
And MardisGrasMax also has N02 in addition to his SC.
IanS
10-12-2002, 11:09 PM
#14
Yea...Matt had his walbro pump BEFORE he got the S/C.....he was using it for a 100-shot. He now runs JUST the walbro pump and removed the aux pump completely.
Russ...what you are saying is PARTIALLY right. If it was all right then the aux fuel pump would be completely useless....the stock fuel pump CAN flow the amount of fuel required for the S/C at upgraded boost levels...BUT it cannot maintain the proper PRESSURE at that flow...this is where the aux fuel pump comes it....it boosts the fuel pressure up so that the injectors get the fuel PRESSURE that they need. Does that make sense???
Russ...what you are saying is PARTIALLY right. If it was all right then the aux fuel pump would be completely useless....the stock fuel pump CAN flow the amount of fuel required for the S/C at upgraded boost levels...BUT it cannot maintain the proper PRESSURE at that flow...this is where the aux fuel pump comes it....it boosts the fuel pressure up so that the injectors get the fuel PRESSURE that they need. Does that make sense???
10-13-2002, 12:05 AM
#15
Originally posted by BlackCat
If you would like the auxiliary fuel pump to be on all of the time
If you would like the auxiliary fuel pump to be on all of the time
Which can be very annoying. That's why I'm glad I got the Walbro pump in there now.
10-13-2002, 12:37 AM
#16
Originally posted by Cumalot
Which can be very annoying. That's why I'm glad I got the Walbro pump in there now.
Which can be very annoying. That's why I'm glad I got the Walbro pump in there now.
10-13-2002, 05:24 AM
#17
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Posts: 6,451
Originally posted by iansw
heh...I wish I had that problem. I can't hear it over the V1 whine, unless I listen for it.
heh...I wish I had that problem. I can't hear it over the V1 whine, unless I listen for it.
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