Need help with Fuel Pump

[offroad16]

Hey all,

I dropped a 5.0L out of an '89 GT about 3 years ago in my Ranger. I put a cobra top end on it from a '94 Cobra (Gt40 heads, Cobra U/L intake, Cobra TB etc). Running 19# injectors and 19# factory MAF. I'm wondering if it wouldn't highly benefit from a bigger fuel pump.

What is the flow of the factory fuel pump in a '93 4.0L Ranger? From what I can find its comparable to the factory Mustang fuel pump which is a 88lph pump. The factory Cobra pump was 110lph!

Most mustang guys ditch the factory pump as soon as they start adding mods. Good rule of thumb is 1/2 HP per LPH. By that rule the factory Ranger pump shouldn't be used beyond 176HP! With the mods I have it should be putting a solid 250HP to the wheels, thats roughly 300HP at the crank. In theory this pump is over driven by a LOT.

This leads me to believe the factory pump is way under powered for my setup. I'm thinking about jumping up to a 155LPH pump or possibly even 190LPH pump. Most mustang guys go with 190lph pump once they start doing H/C/I swaps. But they are rated for nearly 500HP, I think 155lph which is rated for about 425HP would be more ideal for me.

I believe this might fix my long battled troubles of terrible throttle response and just overall performance loss (Terrible acceleration and detonation on the top end with mild timing advance). We don't have to get into the endless amounts of things I've already done to try and fix the performance issues, this post is specifically to discuss fuel pump ideas.

Thoughts?

Thanks!

 

[RangerSVT]

Do you have an A/F or fuel pressure gauge?? This will tell you if you are running lean at any rpm, and then you will know if you need to upgrade your fuel pump. But my odds are, is I would upgrade the pump anyways as a safety reason (as in not to lose the motor from a lean condition)..
SVT

 

[offroad16]

I do not have an AFR gauge. I did buy a Holley Adjustable FPR and set the fuel pressure to factory specs (39psi vac off I believe?). I've never had a fuel gauge hooked up while driving and doing pulls to see if the pressure falls off either.

I did originally have 24# injectors on this truck and swapped them for 19# injectors, this made a big performance increase. Thinking back on it now perhaps it was because the Fuel pump isn't working as hard to drive the 19# injectors?

Check this info out below, as you can see a 88lph (If thats what the ranger fuel pump can even achieve) is only 'safe' for up to a 250HP engine at the crank. I need at least a 110lph and ideally a 155lph by this info:

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

 

[offroad16]

Oops double post!

 

[V8 Level II]

My factory 2003 pump worked OK with the stock Explorer engine w/ 17# injectors but has started to lean out slightly on top with the supercharger and 19# injectors. I have a dash fuel pressure gauge and the pressure clearly begins drop off at high RPM. This pump appears to be at its limit and replacing the filter did nothing to improve it.

I have a 155 pump waiting to go in along with some other engine mods and I think that will be plenty.

 

[offroad16]

The factory mustang 5.0 was rated at 225HP, and the factory 5.0 explorer 210HP. It would make sense to me that a bone stock 5.0 would work just fine with the factory Ranger fuel pump. Start throwing some mild modification to them and quickly you'll be out doing your fuel pump.

How much boost are you running? And what other goodies are you adding? You might want to consider a higher lph pump, especially in a boosted application. Lean conditions with forced induction is NEVER a good thing

I think most mustang guys start looking at 255LPH pumps w/ a return system once you get into H/C/I swaps and Boost. A mild build up on the block and mild boost I'm sure would be just fine on a 155/190lph pump.

How soon do you plan on installing the 155lph pump? I'm VERY curious on the outcome.

I've heard of a few similar cases to mine and a higher lph fuel pump fixed it for them. (seemingly no torque, very sluggish, cannot even burn out in the rain!)

For $75 from mustangs unlimited I might just opt for the 155lph pump, wouldn't hurt things to have proper fuel flow even if it doesn't solve my problem. Which would be faster/easier to replace the pump? Drop the tank or pull the bed? I have herculiner in the bed though, so exposing the bed bolts could be a PITA.

 

[V8 Level II]

My boost is only 5~6 PSI so I think a 155 is more than enough. The stock pump can almost keep up with the blower now and the 155 volume should be roughly double. I currently have the engine out and have a lot to do before it can go back in and get the tune straightened out. Unfortunately, I won't have any results that you could use before the end of summer at the earliest.

I think pulling the bed off is easier but the bedliner over the bolts might make it worth dropping the tank instead.

 

[offroad16]

Your Ranger is an '03? I wonder if they had any higher volume pump because of the 4.0 SOHC. My pump also is original with 220k miles

Luckily for me the previous owner that herculinered the bed didn't do so great and it chips away really easily, the bolts have also been replaced it appears and they are hex so chipping the liner shouldn't be difficult. I really wonder if its going to help with my problem.

I've read 2 other instances of a similar problem to mine, one in a TJ and one in a mustang. Overall performance just sucks, doesn't make power until 3000+ RPM, completely gutless off the line. My 4.0L had significantly more torque and could easily walk away from this V8. In both their cases a larger fuel pump did the trick.

I've already done the following to attempt to fix it:

#Considered issues with ECU, swapped for the A9P for the more aggressive timing tables down low - little to no change.
#Swapped distro out to eliminate pip/tfi - no change
#New cap/rotor/wires/plugs/coil numerous times - no change
#Replaced timing chain to eliminate any slack/cam retard - no change
#Tore engine down to block and replaced all gaskets to eliminate leaks, soaked w/ brake clean to find leaks(none) - no change
#Advanced timing - got to about 14* before it would ping pretty good. I also tried locking it out at ~33* total advance (as far as i got w/o detonation) this obviously helped power but did not fix the bottom end torque issue.
#Tried blocking off PCV system incase it had any vacuum leaks or plumbing was off - no change
#TPS - verified voltages, .98V at idle and smooth flow up to WOT (I forget WOT V reading but it was dead accurate to what i read it should be)
#Codes - only codes I get are for EGR system being gone
#o2 sensors - replaced them at time of engine swap as 1 was bad.
#MAF/Injectors- I've both replaced and CLEANED both 19# and 24# maf's, again the 19# maf made the most improvement but NOT FIXED. 19# injectors were better than the 24# injectors.

I'm out of other ideas on what it could possibly be. Fuel pump might just do it, but if not I have no ideas anymore.

 

[SpongeRanger]

Yea, stock Rangers are about 90lph and a good Mustang needs at least 155lph.

I would try one. Keep us posted.

 

[Mac]

Check your HP on what the stock '94' Cobra motor came with? Think it was 240 at the crank and they ran a different cam (RR's?). Without upgrade cam and some head work, don't see close to 300 hp. Would think the 19#'s would be good for now.
Dave