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Hi Flow Fuel Pump on Stock NSX

Joined
3 November 2004
Messages
83
Location
Brunei
My OEM fuel pump has just failed and I'm planing to get myself a new fuel pump by this weekend. Knowing that OEM fuel pump is expensive, and I think I would get the fuel pump from Walbro.

My question is:
1) If I install Walbro 225 lph fuel pump into my NSX, do I have to replace my fuel pressure regulator, as well? What if I don't, will the high lph of Walbro fuel pump cause any problem to my car fuel supply system? (i.e causing malfunctioning to my oem fuel pressure regulator)

2) What other mod do I have to do, if I use Walbro fuel pump?

Any input will be deeply appreciated. Thanks! :wink:
 
1. Yes, I would recommend an aftermarket fuel pressure regulator to lower the pressure...otherwise, you'll be running pretty rich & you'll be spending more $$$ on fuel.. :wink:

2. If you're close to stock(performance), nothing really...except what you mentioned above...
 
djskyy said:
1. Yes, I would recommend an aftermarket fuel pressure regulator to lower the pressure...otherwise, you'll be running pretty rich & you'll be spending more $$$ on fuel.. :wink:

2. If you're close to stock(performance), nothing really...except what you mentioned above...

Thank you for your info & your input :wink:

So, If I would get myself an adjustable fuel pressure regulator, with 255 lph walbro performance fuel pump, in what pressure range shall I set my pressure regulator? FYI, my car is still a stock NSX.

Thanks again :wink:
 
C30A4 said:
So, If I would get myself an adjustable fuel pressure regulator, with 255 lph walbro performance fuel pump, in what pressure range shall I set my pressure regulator? FYI, my car is still a stock NSX.


What the service manual says....page 11-88 :wink:

with the vacuum line off....46-53psi

with the vacuum line on....36-44psi
 
The Walbro pump only pumps 6GPH more than a stock pump, also you must modify the way the pump mounts in the tank. You will not need a new regulator as the stock one will keep the fuel pressure the same even with a higher output pump.
 
Gerry Johnson said:
You will not need a new regulator as the stock one will keep the fuel pressure the same even with a higher output pump.

Do you have one installed in your fuel tank without replacing your FRP with a higher performance one?

Won't it cause my engine running too rich?

Thanks.
 
djskyy said:
What the service manual says....page 11-88 :wink:

with the vacuum line off....46-53psi

with the vacuum line on....36-44psi

My dear friend, those are the fuel pressure range for stock fuel pump. I don't think it is relevant for a fuel pump which is capable to pump 245 litre per hour of fuel :biggrin:
 
It’s the same pressure

C30A4 said:
those are the fuel pressure range for stock fuel pump. I don't think it is relevant for a fuel pump which is capable to pump 245 litre per hour of fuel
If your engine is stock, why would you not want the same pressure regardless of how much more the aftermarket fuel pump is capable of supplying? If your engine is stock, you want maintain the same pressure to the injectors (which is what the pressures djskyy mentioned measure). This is why djskyy and Gerry said all you need is stock fuel pressure.
 
C30A4 said:
Do you have one installed in your fuel tank without replacing your FRP with a higher performance one?

Won't it cause my engine running too rich?

Thanks.
Yes, I do replace the stock FPR as the 680cc injectors are very hard to get the A/F right at idle at 43psi. I need to turn the fuel pressure down to 28psi so that the car will idle with the correct A/F, I use a completely new fuel system with a 10 micron rated fuel filter and a pump that pumps 90gph, that is around 20-25gph more than the stock pump or the Walbro 255.
 
The point here is, the fuel pump does not control pressure, it just makes it.
The regulator controls pressure by constantly returning an amount of fuel back to the tank. The stock regulators spring, pin, and diaghram are desighned to keep a certain pressure available to the rail, and will do so regardless of volume. At heavy load, vacuum drops and with no vac assist to the diaghram, the spring alone does not hold the pin as high, orifice decrease, less fuel returned, pressure increases.

I would put a stock pump in a stock car. Better fit, no wire cutting (NO a/m pump uses factory wiring-remember Apollo 13) lasts longer, no sweat.

MB
 
Keep in mind that Gerry Johnson's car is highly modified and makes a huge number of horsepower more than stock, whereas C30A4's car is (presumably) the 252 hp stock NSX engine equipped with the automatic transmission. So the two cars have entirely different needs for different fuel pumps.
 
C30A4,I thought your initial consideration for getting Walbro fuel pump was cost. A direct swap of fuel pump and leave the regulator for now would probably be best IMO. If you still want to get the adjustable fuel regulator then set the prssure to what what the manual says. - unless you start serious engine upgrades.
 
C30A4 said:
My dear friend, those are the fuel pressure range for stock fuel pump. I don't think it is relevant for a fuel pump which is capable to pump 245 litre per hour of fuel :biggrin:


I think you misunderstood what I'm trying to say...from my previous experience with Walbro pumps, I always did use an aftermarket fpr...it raised like 20psi in my previous F/I car, that's why I mentioned to get a FPR to tone it down...As for the walbro fuel pumps for NSX, I'm not too sure about the specs, so I guess you can refer to Gerry's statement...
 
Yeah, my first intention of getting walbro fuel pump is to avoid the highly priced OEM fuel pump from the local agent. Which they quote me for about Brunei Dollars $1,034 (US $630) just for the pump & without the installer kits.

Yeah, after I have read all the post from you guys, I really have myself some serious thought and did a bit of research. Yeah, you guys are right :biggrin: I don't think I need to replace my frp, then.

Anyway, I have just found a better deal from sparkplugs.com, which they offer me with a very reasonable price for the pump. It is an oem pump by DENSO. I think i have made the right purchase, as I believes in the quality which DENSO can always offer. It cost me only 85 bulks and I consider it damn cheap already, hee hee :biggrin:

Anyway guys, thank you all for your posts. At least, I have learnt something from all of your inputs. Once agian, thanks!

Caesar
 
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