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255 L/hr Fuel Pump Install

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RB92GT

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Dec 7, 2014
#1
  • Dec 7, 2014
  • #1
I am about to put a 255 l/hr fuel pump in my 92 Mustang as soon the motor is coming out to install a 331 stroker kit and h/c/i package. Do I need to rewire the pump directly to the battery through a relay with heavier wiring? I've heard mixed ideas on this, looking at the specs on the new fuel pump it seems like it will draw 8.5 AMPS maximum, don't want to start any fires.
Thanks!
 

RangerJoe

I leave the horn on while driving
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#2
  • Dec 7, 2014
  • #2
I'VE heard the same, but thousands, myself included, have just done the install without problems.

Joe
 

smkshw

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x2
 

Boosted92LX

It's only an inch or two. What's the big deal?
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#4
  • Dec 7, 2014
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340 lph here. no problems... yet.
 
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jrichker

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Look at the wire gauge sizes, They determine how much current a circuit can safely handle.

The fuel pump wiring on a 92 Mustang is 14 gauge. According to the wire chart it will safely handle 15 amps current.





You grossly oversized the fuel pump requirement for you engine. A 155 LPH pump would have been your best choice.
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”

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.


My Comments:

A lot of people oversize the fuel pump by buying a 255LPH pump thinking that the fuel pump regulator will just pass the excess gas back to the tank. It does, but… Did you ever consider that circulating the fuel around as a 255 LPH pump does will cause the gas to pickup engine heat? What happens to hot gasoline? It boils off or pressurizes the fuel tank! With most of the 5.0 Mustangs having the carbon canister removed or disabled, the car stinks like gas, and the gas mileage drops since the hot fuel evaporates away into the air.
 
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R

RB92GT

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Dec 7, 2014
#6
  • Dec 7, 2014
  • #6
jrichker, thanks for the detailed info... decisions decisions, my thought was "room to grow" with a potential power adder in the future, but I will keep this in mind. I may switch out for a 190... (a 155 leaves me no room to grow and I hate repeating work)
 

madspeed

Colonel Mustard
Founding Member
Nov 29, 1999
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#7
  • Dec 7, 2014
  • #7
A 190 lph is a good choice in my opinion
 
R

RB92GT

Member
Mar 7, 2001
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Dec 7, 2014
#8
  • Dec 7, 2014
  • #8
You're right, swapped it for a 190. The 'merican in me wanted the biggest; bigger is better right. After more research 190 will be best.
 

90lxwhite

I'm kind of a She-Man
5 Year Member
Aug 25, 2011
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Dec 7, 2014
#9
  • Dec 7, 2014
  • #9
jrichker said:
Look at the wire gauge sizes, They determine how much current a circuit can safely handle.

The fuel pump wiring on a 92 Mustang is 14 gauge. According to the wire chart it will safely handle 15 amps current.





You grossly oversized the fuel pump requirement for you engine. A 155 LPH pump would have been your best choice.
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”

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.


My Comments:

A lot of people oversize the fuel pump by buying a 255LPH pump thinking that the fuel pump regulator will just pass the excess gas back to the tank. It does, but… Did you ever consider that circulating the fuel around as a 255 LPH pump does will cause the gas to pickup engine heat? What happens to hot gasoline? It boils off or pressurizes the fuel tank! With most of the 5.0 Mustangs having the carbon canister removed or disabled, the car stinks like gas, and the gas mileage drops since the hot fuel evaporates away into the air.
Click to expand...
Pardon the interuption but thanks Jr that was informative as sh!t. I'm assuming they're talking about flywheel horsepower correct?
 

jrichker

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  • Dec 8, 2014
  • #10
90lxwhite said:
Pardon the interuption but thanks Jr that was informative as sh!t. I'm assuming they're talking about flywheel horsepower correct?
Click to expand...
Flywheel HP is how engine HP is determined by the companies that build engines; it reflects the true performance of the engine. Driveline losses can vary greatly from vehicle to vehicle.

Chassis dynos are a relatively new development of the last 30-40 years. The engine stand dyno has been around for a very long time. the

Besides, the higher HP numbers are a good marketing tool. Most people would buy a 300 HP car instead of a 270 HP car. They wouldn't understand that it's the same HP at the flywheel.
 

TOOLOW91

If you're the village idiot what's that make me?
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#11
  • Dec 8, 2014
  • #11
340 here no problems on the stock harness.
 
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mikestang63

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#12
  • Dec 8, 2014
  • #12
People do get hung up on numbers some time . I remember when they switched from SAE gross HP ( no accessories, belts. transmission and with headers) to net HP ( accessories, belts, transmission and stock exhaust) some 40 years ago. People all freaked why cars had so much more power before the change. Cars that were rated 300 brake HP had to be "faster" than the new fox body mustangs at 225 net HP. lol

That being said, I've run a 255 on most of my N/A cars for decades with no problems and 340 on power adder cars.
 
Reactions: TOOLOW91

addermk2

5 Year Member
Aug 25, 2009
308
87
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Dec 10, 2014
#13
  • Dec 10, 2014
  • #13
jrichker said:
My Comments:

A lot of people oversize the fuel pump by buying a 255LPH pump thinking that the fuel pump regulator will just pass the excess gas back to the tank. It does, but… Did you ever consider that circulating the fuel around as a 255 LPH pump does will cause the gas to pickup engine heat? What happens to hot gasoline? It boils off or pressurizes the fuel tank! With most of the 5.0 Mustangs having the carbon canister removed or disabled, the car stinks like gas, and the gas mileage drops since the hot fuel evaporates away into the air.
Click to expand...

I run a 416lph walbro in my tank and have logged my fuel temps in the return line. At the highest, I've seen my temps 12* higher than ambient. So I don't see where this "boiling the fuel" crap is coming from.

Do you have proof from YOUR car? Or just more of the same copy and paste bull that I have read in every one of your posts.
 

hoopty5.0

mechanicus terribilis
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Dec 14, 2010
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Dec 10, 2014
#14
  • Dec 10, 2014
  • #14
addermk2 said:
I run a 416lph walbro in my tank and have logged my fuel temps in the return line. At the highest, I've seen my temps 12* higher than ambient. So I don't see where this "boiling the fuel" crap is coming from.

Do you have proof from YOUR car? Or just more of the same copy and paste bull**** that I have read in every one of your posts.
Click to expand...
Copy and paste? Probably. But the vast majority of the information posted is pertinent and extraordinarily useful. It has kept my car and many, many others on the road by helping me sift through a string of unrelated issues that I would have wasted countless hours diagnosing otherwise.

Your attitude is not appreciated in here and you are welcome to crawl back under whatever rock you've been under since 2009.
 
Reactions: tca7291 and doobismaximus

Gearbanger 101

Straight Outta Locash
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#15
  • Dec 10, 2014
  • #15
Running a 255lph "high pressure" pump on my 331....no issues. I did install it with plans to spray the engine though....otherwise I probably would have just stuck with a 155-190lph unit.
 

tca7291

I can see your wieners.
5 Year Member
Sep 1, 2011
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Dec 10, 2014
#16
  • Dec 10, 2014
  • #16
@hoopty5.0 , you forgot the smiley:
 

hoopty5.0

mechanicus terribilis
15 Year Member
Dec 14, 2010
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Dec 10, 2014
#17
  • Dec 10, 2014
  • #17
tca7291 said:
@hoopty5.0 , you forgot the smiley:
Click to expand...
Nah. Once people realize this isn't a d*ck measuring contest and that we're all here to help, it all settles out.
 

tca7291

I can see your wieners.
5 Year Member
Sep 1, 2011
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#18
  • Dec 10, 2014
  • #18
Ehh, I guess being a member for 5 1/2 years with only 21 posts is kind of self explanatory. It rubs me the wrong way when someone bad talks "the master."
 

addermk2

5 Year Member
Aug 25, 2009
308
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Dec 10, 2014
#19
  • Dec 10, 2014
  • #19
tca7291 said:
Ehh, I guess being a member for 5 1/2 years with only 21 posts is kind of self explanatory. It rubs me the wrong way when someone bad talks "the master."
Click to expand...
Anyone with a keyboard can ctrl-v... my issue is with the bad tech of "not using a 255LPH pump because it'll boil your fuel"

Which is laughable.
 
R

RB92GT

Member
Mar 7, 2001
42
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Jacksonville, FL
Dec 10, 2014
#20
  • Dec 10, 2014
  • #20
Wow, getting a little excited over a $100 fuel pump choice, lol. I decided to go with the 190 mainly due to the Amp draw of 5 instead of 8. If I decide to add a power adder in the future I'll spend another $100 and get a 255, no big deal... Oh ya, and Amazon has a 190 Walbro GSS242 for $53 right now (pump only, install kit another $19 from latemodelrestoration.com).
 
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