High flow fuel pump

[4AU4LIFE]

Ok guys, school me on this too please.
If you have a higher flowing fuel pump(than stock), does it ALWAYS flow the higher amount or does it do it variabley? If it is variable, what determines when it engages the flow and are there different levels of the flow?

 

[BadCarma]

Hi Maurice,
If you step up to a more powerful fuel pump (this is my recommendation: (Walbro 255 hp) it can be had here for $116 part #FPH006
http://www.autoperformanceengineering.com/

Your fuel systems fuel pressure regulator has a return line that will return fuel to the tank that the motor does not need. the Walbro will use the factory hangers.

hope that helped BTW good move!

Best Regards David

 

[sjs]

There are really two issues, flow (volume) and pressure. They are of course related but not the same. The answer to your question is that the injectors control the flow as dictated by the computer. However, they don't really meter volume. The computer relies on the fuel pressure to be at a certain level so that when it opens the injectors for a certain period of time, they deliver the required volume. So, there is also a fuel pressure regulator that holds the pressure constant regardless of demand, therefore it too plays a role in flow control.

When you go to a fuel pump of greater capacity and/or pressure, the regulator still does its job, but the "bigger" pump allows you to increase demand without flowing so much that the pump can't keep up, thereby causing the pressure to drop and supply fall behind demand.

Make sense?

One thing to watch out for with higher pressure pumps is that the stock regulator has an orifice that allows excess fuel to bleed back to the tank. A pump of greater capacity and pressure can overwhelm the orifice and cause pressure fluctuation, so a new regulator is recommended. AEM has a nice direct replacement.

 

[mc-ca]

Does the stock fuel pump ever fall behind and lower the performance? Sounds like a basic engineering mistake if it does.

 

[sjs]

Oh, David answered while I was typing. Well, hopefully the extra details are useful.

BTW, I highly recommend the same vendor for the pump.

 

[sjs]

Does the stock fuel pump ever fall behind and lower the performance? Sounds like a basic engineering mistake if it does.

All things age, even you some day.

I've not heard of frequent problems on stock cars even with 100k+ miles, but some have been unable to keep up the demand on modestly boosted cars, mine included, and high boost cars are sure to need help. When that happens it's more than just performance that suffers.

 

[Yellow Rose]

One thing to watch out for with higher pressure pumps is that the stock regulator has an orifice that allows excess fuel to bleed back to the tank. A pump of greater capacity and pressure can overwhelm the orifice and cause pressure fluctuation, so a new regulator is recommended. AEM has a nice direct replacement.

Hey Steve - are you running one of AEM's FPR? Is it just a standard FPR or a RRFPR? Do you have a part number?

 

[BadCarma]

Hey Steve - are you running one of AEM's FPR? Is it just a standard FPR or a RRFPR? Do you have a part number? [/B]

Ditto

David

 

[sjs]

Andy, David,

Yes, I have their FPR. It is an adjustable "fixed" rate regulator. "Fixed" in quotes because like the stock one it does connect to manifold pressure and increase/decrease in direct proportion to manifold pressure to maintain a constant effective pressure blowing into the manifold. It comes with several different bleeder orifice sizes.

The part number (25-303) is the same as some Accords and other cars so it is fairly common, and it comes in three colors, red, blue and silver (clear coat). Retail is about $235 but low street price is around $155. Still pretty steep, but worth it for a direct replacement. Thinking back, I vaguely recall that the metal bleed line was a bit small for the NSX fuel line, and one other downside is that unlike their (an other) generic units it is not tapped for a pressure gauge. Otherwise very nice.

 

[BadCarma]

Steve, so thats what you have been using to play with your pressure. any leaks due to the fitment at 90 psi? I am on the fence on that one right now, I really wanted one I good plug a FPG into but their are plenty of solutions for that but I dont like to kludge unless I have to.
David

 

[4AU4LIFE]

But on a car running n/a and no NOS, there would be no real benefit from getting a high flow pump then correct?

 

[sjs]

David,

No problems with leaks. It seals with a small o-ring just like the stock one. It couldn't be a cleaner install, and the same size as stock (a bit taller maybe) which is why no place for a gauge. I think tapping a stock fuel rail might be a solution, although there isn't much room. If I weren't so lazy I might get new rails but I'd need to make them from generic pieces.

 

[sjs]

But on a car running n/a and no NOS, there would be no real benefit from getting a high flow pump then correct?

Absolutely correct. The stock unit is more than adequate when functioning correctly and your filter is not half clogged.

 

[BadCarma]

David,

If I weren't so lazy I might get new rails but I'd need to make them from generic pieces.

I have been thinking about buying the raw stock they sell to roll your own. you can find it in sizes very close to the stock rails

 

[4AU4LIFE]

Absolutely correct. The stock unit is more than adequate when functioning correctly and your filter is not half clogged.

thnx