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Fuel Pump

  • Thread starter Thread starter 7upstang91
  • Start date Start date Nov 30, 2009

7upstang91

10 Year Member
May 30, 2008
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124
74
Florida
Nov 30, 2009
#1
  • Nov 30, 2009
  • #1
I know my fuel pump is going bad. It starts sucking and air with about 4 gallons of gas in the tank, and hesitates and backfires. The car has done this for awhile. So if I get a 255 fuel pump, what else do I have to do? This is going in the Notch with only #24 injectors.
 

liljoe07

5 Year Member
Feb 18, 2009
1,622
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Cartersville,Ga
Nov 30, 2009
#2
  • Nov 30, 2009
  • #2
Just get the 255 and throw it in. Dont have to do anything else.
 

7upstang91

10 Year Member
May 30, 2008
936
124
74
Florida
Nov 30, 2009
#3
  • Nov 30, 2009
  • #3
liljoe07 said:
Just get the 255 and throw it in. Dont have to do anything else.
Click to expand...

THank you! It will work fine?
 

liljoe07

5 Year Member
Feb 18, 2009
1,622
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Cartersville,Ga
Nov 30, 2009
#4
  • Nov 30, 2009
  • #4
Yep.

If your worried about the bigger pump pushing to much pressure, dont. Thats what the regulator is for.
 

7upstang91

10 Year Member
May 30, 2008
936
124
74
Florida
Nov 30, 2009
#5
  • Nov 30, 2009
  • #5
yes that was my concern. Thank you very much. The car is pretty much stock motor wise, but I might as well buy for the future.
 

jrichker

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Dublin GA
Nov 30, 2009
#6
  • Nov 30, 2009
  • #6
Copied from the FORD RACING PERFORMANCE PARTS catalog:
PROPERLY SIZING FUEL SYSTEM COMPONENTS
Fuel Pumps
The following information is presented assuming the above information has been taken into consideration regarding BSFC, fuel pressure and specific gravity of the fuel being used. Most fuel pumps for electronic fuel injection are rated for flow at 12 volts @ 40 PSI. Most vehicle charging systems operate anywhere from 13.2v to 14.4v. The more voltage you feed a pump, the faster it spins which, obviously, will put out more fuel. Rating a fuel pump at 12 volts then, should offer a fairly conservative fuel flow rating allowing you to safely determine the pump’s ability to supply an adequate amount of fuel for a particular application.

As previously mentioned, engines actually require a certain WEIGHT of fuel, NOT a certain VOLUME of fuel per horsepower. This can offer a bit of confusion since most fuel pumps are rated by volume, and not by weight. To determine the proper fuel pump required, a few mathematical conversions will need to be performed using the following information. There are 3.785 liters in 1 US Gallon. 1 gallon of gasoline (.72 specific gravity @ 65° F) weighs 6.009 LBS.

To be certain that the fuel pump is not run to its very limit, which could potentially be dangerous to the engine, multiply the final output of the fuel pump by 0.9 to determine the capacity of the fuel pump at 90% output. This should offer plenty of ‘cushion’ as to the overall “horsepower capacity” of the fuel pump.

To determine the overall capacity of a fuel pump rated in liters, use the additional following conversions:
(Liters per Hour) / 3.785 = Gallons
Multiply by 6.009 = LBS/HR
Multiply by 0.9 = Capacity at 90%
Divide by BSFC = Horsepower Capacity
So for a 110 LPH fuel pump:
110 / 3.785 = 29.06 Gallons
29.06 x 6.009 = 174.62 LBS/HR
174.62 x 0.9 = 157 LBS/HR @ 90% Capacity
157 / 0.5 = 314 HP safe naturally aspirated “Horsepower Capacity”

Here's a chart for those of us too lazy to do the math or don't have a calculator handy...

Safe “Horsepower Capacity” @ 40 PSI with 12 Volts

60 Liter Pump = 95 LB/HR X .9 = 86 LB/HR, Safe for 170 naturally aspirated Horsepower
88 Liter Pump = 140 LB/HR X .9 = 126 LB/HR, Safe for 250 naturally aspirated Horsepower
110 Liter Pump = 175 LB/HR X .9 = 157 LB/HR, Safe for 315 naturally aspirated Horsepower
155 Liter Pump = 246 LB/HR X .9 = 221 LB/HR, Safe for 440 naturally aspirated Horsepower
190 Liter Pump = 302 LB/HR X .9 = 271 LB/HR, Safe for 540 naturally aspirated Horsepower
255 Liter Pump = 405 LB/HR X .9 = 364 LB/HR, Safe for 700 naturally aspirated Horsepower

Note: For forced induction engines, the above power levels will be reduced because as the pressure required by the pump increases, the flow decreases. In order to do proper fuel pump sizing, a fuel pump map is required, which shows flow rate versus delivery pressure.

That is, a 255 liter per hour pump at 40 PSI may only supply 200 liters per hour at 58 PSI (40 PSI plus 18 lbs of boost). Additionally, if you use a fuel line that is not large enough, this can result in decreased fuel volume due to the pressure drop across the fuel feed line: 255 LPH at the pump may only result in 225 LPH at the fuel rail.
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,160
17,854
224
Massachusetts
Nov 30, 2009
#7
  • Nov 30, 2009
  • #7
Do you have 24# injectors with the stock speed density system? If so, that could be an issue there in itself.
 

7upstang91

10 Year Member
May 30, 2008
936
124
74
Florida
Dec 1, 2009
#8
  • Dec 1, 2009
  • #8
No it matches up, they are correct. So Jrichker, I will be fine with the 255 on my basicly stock stang? Can you help with my starter as well?
 
G

gixxerguy2004

New Member
Nov 30, 2009
8
0
0
easton, pa
Dec 1, 2009
#9
  • Dec 1, 2009
  • #9
a 255 is a pretty big pump i think their rated for up to like 720 hp u could always go wit the 190 (i'm pretty sure its a 190) also i think thats rated for like 500 somthing hp. just another option for ya if your worried bout ur injector size. in my car i have the 255 pump wit 40 lb injectors and about 29lbs of fuel pressure. and i run rich. so the 255 deff pumps out alot....
 

7upstang91

10 Year Member
May 30, 2008
936
124
74
Florida
Dec 1, 2009
#10
  • Dec 1, 2009
  • #10
yes but I hope to be in a 408 by next August
 
G

gixxerguy2004

New Member
Nov 30, 2009
8
0
0
easton, pa
Dec 2, 2009
#11
  • Dec 2, 2009
  • #11
oh ok then deff go wit a 255 so u dont have to backtrack and upgrade the pump again when u do ur upgrade
 
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